diff --git a/calendar/base/build/calBaseModule.cpp b/calendar/base/build/calBaseModule.cpp
index 2f3d549e07b..dcfa305d983 100644
--- a/calendar/base/build/calBaseModule.cpp
+++ b/calendar/base/build/calBaseModule.cpp
@@ -46,28 +46,37 @@
 #include "calDuration.h"
 #include "calPeriod.h"
 #include "calICSService.h"
+#include "calTimezoneService.h"
 #include "calRecurrenceRule.h"
 #include "calRecurrenceDate.h"
 #include "calRecurrenceDateSet.h"
 
 #include "calBaseCID.h"
 
-NS_GENERIC_FACTORY_CONSTRUCTOR(calDateTime)
 NS_GENERIC_FACTORY_CONSTRUCTOR(calDuration)
-NS_GENERIC_FACTORY_CONSTRUCTOR(calPeriod)
-NS_GENERIC_FACTORY_CONSTRUCTOR(calICSService)
-NS_GENERIC_FACTORY_CONSTRUCTOR(calRecurrenceRule)
-NS_GENERIC_FACTORY_CONSTRUCTOR(calRecurrenceDate)
-NS_GENERIC_FACTORY_CONSTRUCTOR(calRecurrenceDateSet)
-
-NS_DECL_CLASSINFO(calDateTime)
 NS_DECL_CLASSINFO(calDuration)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(calPeriod)
 NS_DECL_CLASSINFO(calPeriod)
-NS_DECL_CLASSINFO(calICSService)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(calRecurrenceRule)
 NS_DECL_CLASSINFO(calRecurrenceRule)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(calRecurrenceDate)
 NS_DECL_CLASSINFO(calRecurrenceDate)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(calRecurrenceDateSet)
 NS_DECL_CLASSINFO(calRecurrenceDateSet)
 
+NS_GENERIC_FACTORY_CONSTRUCTOR(calDateTime)
+NS_DECL_CLASSINFO(calDateTime)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(calICSService)
+NS_DECL_CLASSINFO(calICSService)
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(calTimezoneService)
+NS_DECL_CLASSINFO(calTimezoneService)
+
 static const nsModuleComponentInfo components[] =
 {
     { "Calendar DateTime Object",
@@ -114,6 +123,17 @@ static const nsModuleComponentInfo components[] =
       NULL,
       &NS_CLASSINFO_NAME(calICSService)
     },
+    { "Timezone Service",
+      CAL_TIMEZONESERVICE_CID,
+      CAL_TIMEZONESERVICE_CONTRACTID,
+      calTimezoneServiceConstructor,
+      NULL,
+      NULL,
+      NULL,
+      NS_CI_INTERFACE_GETTER_NAME(calTimezoneService),
+      NULL,
+      &NS_CLASSINFO_NAME(calTimezoneService)
+    },
     { "Calendar Recurrence Rule",
       CAL_RECURRENCERULE_CID,
       CAL_RECURRENCERULE_CONTRACTID,
diff --git a/calendar/base/content/calendar-decorated-month-view.xml b/calendar/base/content/calendar-decorated-month-view.xml
index c057f71e85c..3ffb52571f9 100644
--- a/calendar/base/content/calendar-decorated-month-view.xml
+++ b/calendar/base/content/calendar-decorated-month-view.xml
@@ -120,7 +120,7 @@
                        this.calView.goToDay(this.calView.selectedDay);
                        break;
                    case "calendar.timezone.local":
-                       this.calView.viewElem.timezone = subj.getCharPref(pref);
+                       this.calView.viewElem.timezone = calendarDefaultTimezone();
                        if (!this.calView.startDay || !this.calView.endDay) {
                            // Don't refresh if we're not initialized
                            return;
diff --git a/calendar/base/content/calendar-decorated-multiday-base-view.xml b/calendar/base/content/calendar-decorated-multiday-base-view.xml
index 3e00663681e..53b938c3ee2 100644
--- a/calendar/base/content/calendar-decorated-multiday-base-view.xml
+++ b/calendar/base/content/calendar-decorated-multiday-base-view.xml
@@ -163,7 +163,7 @@
                             break;
 
                         case "calendar.timezone.local":
-                            this.viewElem.timezone = aSubject.getCharPref(aPreference);
+                            this.viewElem.timezone = calendarDefaultTimezone();
                             if (!this.startDay || !this.endDay) {
                                 // don't refresh if we're not initialized
                                 return;
diff --git a/calendar/base/content/calendar-decorated-multiweek-view.xml b/calendar/base/content/calendar-decorated-multiweek-view.xml
index f8380dfc14e..4962bf2f03d 100644
--- a/calendar/base/content/calendar-decorated-multiweek-view.xml
+++ b/calendar/base/content/calendar-decorated-multiweek-view.xml
@@ -132,7 +132,7 @@
                        this.calView.goToDay(this.calView.selectedDay);
                        break;
                    case "calendar.timezone.local":
-                       this.calView.viewElem.timezone = subj.getCharPref(pref);
+                       this.calView.viewElem.timezone = calendarDefaultTimezone();
                        if (!this.calView.startDay || !this.calView.endDay) {
                            // Don't refresh if we're not initialized
                            return;
diff --git a/calendar/base/content/calendar-dnd-listener.js b/calendar/base/content/calendar-dnd-listener.js
index 4e9010e1530..67290d27023 100644
--- a/calendar/base/content/calendar-dnd-listener.js
+++ b/calendar/base/content/calendar-dnd-listener.js
@@ -71,7 +71,7 @@ var calendarDNDObserver = {
             case "text/calendar":
                 var parser = Components.classes["@mozilla.org/calendar/ics-parser;1"]
                              .createInstance(Components.interfaces.calIIcsParser);
-                parser.parseString(data);
+                parser.parseString(data, null);
                 startBatchTransaction();
                 try {
                     for each (var item in parser.getItems({})) {
@@ -150,7 +150,7 @@ var calendarDNDObserver = {
                             }
                             var parser = Components.classes["@mozilla.org/calendar/ics-parser;1"]
                                          .createInstance(Components.interfaces.calIIcsParser);
-                            parser.parseString(str);
+                            parser.parseString(str, null);
                             startBatchTransaction();
                             try {
                                 for each (var item in parser.getItems({})) {
diff --git a/calendar/base/content/calendar-month-view.xml b/calendar/base/content/calendar-month-view.xml
index 80d8bf0015b..1e17c5becd0 100644
--- a/calendar/base/content/calendar-month-view.xml
+++ b/calendar/base/content/calendar-month-view.xml
@@ -836,6 +836,7 @@
             hdr.index = i;
           }
 
+          this.mTimezone = floating();
           var alarmService = Components.classes['@mozilla.org/calendar/alarm-service;1']
                              .getService(Components.interfaces.calIAlarmService);
           alarmService.addObserver(this.mObserver);
@@ -857,7 +858,7 @@
       <field name="mStartDate">null</field>
       <field name="mEndDate">null</field>
       <field name="mDateBoxes">null</field>
-      <field name="mTimezone">"floating"</field>
+      <field name="mTimezone">null</field>
 
       <field name="mSelectedItems">[]</field>
       <field name="mSelectedDayBox">null</field>
diff --git a/calendar/base/content/calendar-multiday-view.xml b/calendar/base/content/calendar-multiday-view.xml
index 00fe8f374aa..01d2e9fd8de 100644
--- a/calendar/base/content/calendar-multiday-view.xml
+++ b/calendar/base/content/calendar-multiday-view.xml
@@ -265,6 +265,7 @@
     <implementation>
       <constructor><![CDATA[
         this.mEvents = Array();
+        this.mTimezone = UTC();
       ]]></constructor>
 
       <!-- fields -->
@@ -277,7 +278,7 @@
       <field name="mEventMap">null</field>
       <field name="mCalendarView">null</field>
       <field name="mDate">null</field>
-      <field name="mTimezone">"UTC"</field>
+      <field name="mTimezone">null</field>
       <field name="mDragState">null</field>
       <field name="mLayoutBatchCount">0</field>
       <!-- Since we'll often be getting many events in rapid succession, this
@@ -339,7 +340,7 @@
         <setter><![CDATA[
           this.mDate = val;
 
-          if (val.timezone != this.mTimezone) {
+          if (!compareObjects(val.timezone, this.mTimezone)) {
               //dump ("++ column tz: " + val.timezone + "\n");
               this.mTimezone = val.timezone;
               if (!this.mLayoutBatchCount) {
@@ -540,11 +541,11 @@
            var stdate = aOccurrence.startDate || aOccurrence.entryDate;
            var enddate = aOccurrence.endDate || aOccurrence.dueDate;
 
-           if (stdate.timezone != this.mTimezone) {
+           if (!compareObjects(stdate.timezone, this.mTimezone)) {
                stdate = stdate.getInTimezone (this.mTimezone);
            }
 
-           if (enddate.timezone != this.mTimezone) {
+           if (!compareObjects(enddate.timezone, this.mTimezone)) {
                enddate = enddate.getInTimezone (this.mTimezone);
            }
 
@@ -1151,7 +1152,7 @@
                   // that's why i'm clipping the start- and end-time to the
                   // timespan of this column.
                   var start = data.item.startDate || data.item.entryDate;
-                  if (start.timezone != this.mTimezone) {
+                  if (!compareObjects(start.timezone, this.mTimezone)) {
                       start = start.getInTimezone(this.mTimezone);
                   }
                   if (start.year  != this.date.year ||
@@ -1165,7 +1166,7 @@
                                     start.timezone);
                   }
                   var end = data.item.endDate || data.item.dueDate;
-                  if (end.timezone != this.mTimezone) {
+                  if (!compareObjects(end.timezone, this.mTimezone)) {
                       end = end.getInTimezone(this.mTimezone);
                   }
                   if (end.year  != this.date.year ||
@@ -1189,7 +1190,7 @@
                       prevEnd.hour = 0;
                       prevEnd.minute = this.mStartMin;
                   }
-                  prevEnd.timezone = "floating";
+                  prevEnd.timezone = floating();
                   // the reason why we need to calculate time durations
                   // based on floating timezones is that we need avoid
                   // dst gaps in this case. converting the date/times to
@@ -1197,13 +1198,13 @@
                   // we explicitly don't use getInTimezone() as it would
                   // be slightly more expensive in terms of performance.
                   var floatstart = start.clone();
-                  floatstart.timezone = "floating";
+                  floatstart.timezone = floating();
                   var dur = floatstart.subtractDate(prevEnd);
                   if (dur.inSeconds) {
                       col.push({duration: dur});
                   }
                   var floatend = end.clone();
-                  floatend.timezone = "floating";
+                  floatend.timezone = floating();
                   col.push({event: data.item,
                             endDate: end,
                             duration: floatend.subtractDate(floatstart)});
@@ -2190,6 +2191,7 @@
       <field name="mResizeHandler">null</field>
       <constructor><![CDATA[
         var self = this;
+        this.mTimezone = UTC();
         this.mResizeHandler = function resizeHandler() { self.onResize(); };
         window.addEventListener("resize", this.mResizeHandler, true);
         this.mScrollHandler = function scrollHandler() { self.onScroll(); };
@@ -2300,7 +2302,7 @@
       <field name="mShowCompleted">false</field>
       <field name="mDisplayDaysOff">true</field>
       <field name="mDaysOffArray">[0,6]</field>
-      <field name="mTimezone">"UTC"</field>
+      <field name="mTimezone">null</field>
       <field name="mFlashingEvents">new Object()</field>
 
       <field name="mObserver"><![CDATA[
diff --git a/calendar/base/content/preferences/timezones.js b/calendar/base/content/preferences/timezones.js
index 40ddf2b02d3..920e6a04929 100644
--- a/calendar/base/content/preferences/timezones.js
+++ b/calendar/base/content/preferences/timezones.js
@@ -45,7 +45,7 @@ var gTimezonesPane = {
 
         if (!prefValue) {
             prefValue = calendarDefaultTimezone();
-            tzMenuList.value = prefValue;
+            tzMenuList.value = prefValue.tzid;
         }
     }
 };
diff --git a/calendar/base/public/Makefile.in b/calendar/base/public/Makefile.in
index ff0c499ebae..a70af599459 100644
--- a/calendar/base/public/Makefile.in
+++ b/calendar/base/public/Makefile.in
@@ -82,6 +82,7 @@ XPIDLSRCS	= calIAlarmService.idl \
 		  calIOperation.idl \
 		  calIFreeBusyProvider.idl \
 		  calICalendarSearchProvider.idl \
+		  calITimezoneProvider.idl \
 		  $(NULL)
 
 EXPORTS		= calBaseCID.h
diff --git a/calendar/base/public/calBaseCID.h b/calendar/base/public/calBaseCID.h
index b80f80e2e9c..ec91641d981 100644
--- a/calendar/base/public/calBaseCID.h
+++ b/calendar/base/public/calBaseCID.h
@@ -61,6 +61,11 @@
 #define CAL_ICSSERVICE_CONTRACTID \
     "@mozilla.org/calendar/ics-service;1"
 
+#define CAL_TIMEZONESERVICE_CID \
+    { 0x1a23ace4, 0xa0dd, 0x43b4, { 0x96, 0xa8, 0xb3, 0xcd, 0x41, 0x9a, 0x14, 0xa5 } }
+#define CAL_TIMEZONESERVICE_CONTRACTID \
+    "@mozilla.org/calendar/timezone-service;1"
+
 #define CAL_RECURRENCERULE_CID \
     { 0xd9560bf9, 0x3065, 0x404a, { 0x90, 0x4c, 0xc8, 0x82, 0xfc, 0x9c, 0x9b, 0x74 } }
 #define CAL_RECURRENCERULE_CONTRACTID \
diff --git a/calendar/base/public/calIAlarmService.idl b/calendar/base/public/calIAlarmService.idl
index 952df93e48c..b2be8111417 100644
--- a/calendar/base/public/calIAlarmService.idl
+++ b/calendar/base/public/calIAlarmService.idl
@@ -40,6 +40,7 @@
 interface calIItemBase;
 interface calICalendar;
 interface calIDuration;
+interface calITimezone;
 
 [scriptable,uuid(c9c97643-db45-4790-9441-05384ae5c272)]
 interface calIAlarmServiceObserver : nsISupports
@@ -70,7 +71,7 @@ interface calIAlarmService : nsISupports
    * This is the timezone that all-day events will be converted to in order to
    * determine when their alarms should fire.
    */
-  attribute AUTF8String timezone;
+  attribute calITimezone timezone;
 
   /**
    * Cause the alarm service to start up, create a list of upcoming
diff --git a/calendar/base/public/calIDateTime.idl b/calendar/base/public/calIDateTime.idl
index fea652ba04a..9327255845d 100644
--- a/calendar/base/public/calIDateTime.idl
+++ b/calendar/base/public/calIDateTime.idl
@@ -40,6 +40,7 @@
 #include "nsISupports.idl"
 
 interface calIDuration;
+interface calITimezone;
 [ptr] native icaltimetypeptr(struct icaltimetype);
 
 [scriptable, uuid(5678d4a3-2543-4ece-afbb-079292f2866e)]
@@ -120,21 +121,11 @@ interface calIDateTime : nsISupports
   /**
    * Gets or sets the timezone of this calIDateTime instance.
    * Setting the timezone does not change the actual date/time components;
-   * to convert between timezones, use getInTimezone(). 
+   * to convert between timezones, use getInTimezone().
    *
-   * Valid values are:
-   *
-   * - "UTC" (or "utc", "UTC" preferred)
-   *   - the object refers to a time in UTC.
-   * - a TZID string, understood by the ICS Service
-   *   - the object refers to a time in that tz
-   * - "floating"
-   *   - the object is in floating time and does not have an
-   *     associated timezone.
-   *
-   * @throws NS_ERROR_INVALID_ARG if an invalid timezone is passed in.
+   * @throws NS_ERROR_INVALID_ARG if null is passed in.
    */
-  attribute AUTF8String timezone;
+  attribute calITimezone timezone;
 
   /**
    * Resets the datetime object.
@@ -145,12 +136,12 @@ interface calIDateTime : nsISupports
    * @param hour     hour, 0-23
    * @param minute   minute, 0-59
    * @param second   decond, 0-59
-   * @param timezone timezone, e.g. "UTC", "floating", "Europe/Berlin"
+   * @param timezone timezone
    *
    * The passed datetime will be normalized, e.g. a minute value of 60 will
    * increase the hour.
    *
-   * @throws NS_ERROR_INVALID_ARG if an invalid timezone is passed in.
+   * @throws NS_ERROR_INVALID_ARG if no timezone is passed in.
    */
   void resetTo(in short year,
                in short month,
@@ -158,7 +149,7 @@ interface calIDateTime : nsISupports
                in short hour,
                in short minute,
                in short second,
-               in AUTF8String timezone);
+               in calITimezone timezone);
 
   /**
    * The offset of the timezone this datetime is in, relative to UTC, in
@@ -205,11 +196,9 @@ interface calIDateTime : nsISupports
   /**
    * Set the value of this calIDateTime instance
    * to aTime milliseconds since the epoch in the
-   * given timezone.  Valid values for the aTimezone
-   * are either a known TZID or "UTC"; null/empty string
-   * is not valid.
+   * given timezone.
    */
-  void setTimeInTimezone (in PRTime aTime, in AUTF8String aTimezone);
+  void setTimeInTimezone(in PRTime aTime, in calITimezone aTimezone);
 
   /**
    * Return a new calIDateTime instance that's the result of
@@ -218,7 +207,7 @@ interface calIDateTime : nsISupports
    * the "floating" timezone is given, then this object
    * is just cloned, and the timezone is set to floating.
    */
-  calIDateTime getInTimezone (in AUTF8String aTimezone);
+  calIDateTime getInTimezone(in calITimezone aTimezone);
 
   // add the given calIDateTime, treating it as a duration, to
   // this item.
diff --git a/calendar/base/public/calIICSService.idl b/calendar/base/public/calIICSService.idl
index bf03a46209e..70ad6e5fce0 100644
--- a/calendar/base/public/calIICSService.idl
+++ b/calendar/base/public/calIICSService.idl
@@ -21,6 +21,7 @@
  *
  * Contributor(s):
  *   Mike Shaver <shaver@off.net>
+ *   Daniel Boelzle <daniel.boelzle@sun.com>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either the GNU General Public License Version 2 or later (the "GPL"), or
@@ -44,6 +45,8 @@
 interface calIItemBase;
 interface calIDateTime;
 interface calIDuration;
+interface calITimezone;
+interface calITimezoneProvider;
 
 interface calIIcalProperty;
 interface nsIUTF8StringEnumerator;
@@ -51,6 +54,7 @@ interface nsIInputStream;
 
 [ptr] native icalpropertyptr(struct icalproperty_impl);
 [ptr] native icalcomponentptr(struct icalcomponent_impl);
+[ptr] native icaltimezoneptr(struct _icaltimezone);
 
 /**
  * General notes:
@@ -127,6 +131,11 @@ interface calIIcalComponent : nsISupports
     
     AUTF8String serializeToICS();
 
+    /**
+     * Return a string representation of this instance.
+     */
+    AUTF8String toString();
+
     /**
      * Serializes this component (and subcomponents) directly to an
      * input stream.  Typically used for performance to avoid
@@ -140,7 +149,9 @@ interface calIIcalComponent : nsISupports
     nsIInputStream serializeToICSStream();
 
     void addSubcomponent(in calIIcalComponent comp);
-    void removeSubcomponent(in calIIcalComponent comp);
+// If you add then remove a property/component, the referenced
+// timezones won't get purged out. There's currently no client code.
+//     void removeSubcomponent(in calIIcalComponent comp);
 
     /**
      * @param kind ANY, ATTENDEE, X-WHATEVER, etc.
@@ -148,36 +159,35 @@ interface calIIcalComponent : nsISupports
     calIIcalProperty getFirstProperty(in AUTF8String kind);
     calIIcalProperty getNextProperty(in AUTF8String kind);
     void addProperty(in calIIcalProperty prop);
-    void removeProperty(in calIIcalProperty prop);
+// If you add then remove a property/component, the referenced
+// timezones won't get purged out. There's currently no client code.
+//     void removeProperty(in calIIcalProperty prop);
 
     /**
      * Timezones need special handling, as they must be
      * emitted as children of VCALENDAR, but can be referenced by
-     * any sub component.  The components this expects to receive
-     * are VCALENDAR components with a single VTIMEZONE child.
-     * Adding the same TZID twice will cause the second and later
-     * adds to be ignored.  Appropriate calIIcalComponents can
-     * be obtained via the calIICSService.
+     * any sub component.
+     * Adding a second timezone (of the same TZID) will remove the
+     * first one.
      */
-    void addTimezoneReference(in calIIcalComponent aTimezone);
+    void addTimezoneReference(in calITimezone aTimezone);
 
     /**
-     * Returns an array of VCALENDAR components, each with a single
-     * VTIMEZONE.  These are the timezones that are in use by this
-     * component and its children.  Child timezones are only added
-     * at addSubcomponent time.
+     * Returns an array of VTIMEZONE components.
+     * These are the timezones that are in use by this
+     * component and its children.
      */
     void getReferencedTimezones(out PRUint32 aCount,
-                                [array,size_is(aCount),retval] out calIIcalComponent aTimezones);
+                                [array,size_is(aCount),retval] out calITimezone aTimezones);
 
     /**
      * Clones the component. The cloned component is decoupled from any parent.
      * @return cloned component
      */
     calIIcalComponent clone();
-    
+
     [noscript,notxpcom] icalcomponentptr getIcalComponent();
-    [noscript, notxpcom] nsresult addTimezoneReferenceById(in ACStringPtr tzid);
+    [noscript,notxpcom] icaltimezoneptr getIcalTimezone();
 };
 
 [scriptable,uuid(17349a10-5d80-47fa-9bea-f22957357675)]
@@ -188,6 +198,11 @@ interface calIIcalProperty : nsISupports
      * @exception Any libical error will be thrown as an calIError::ICS_ error.
      */
     readonly attribute AUTF8String icalString;
+
+    /**
+     * Return a string representation of this instance.
+     */
+    AUTF8String toString();
     
     /**
      * The value of the property as string.
@@ -204,8 +219,7 @@ interface calIIcalProperty : nsISupports
 
     /**
      * The value of the property as date/datetime value, keeping
-     * track of the used timezone being resolvable and referenced in the
-     * owning component.
+     * track of the used timezone referenced in the owning component.
      */
     attribute calIDateTime valueAsDatetime;
 
@@ -237,51 +251,23 @@ interface calIIcalProperty : nsISupports
 [scriptable,uuid(ae4ca6c3-981b-4f66-a0ce-2f2c218ad9e3)]
 interface calIICSService : nsISupports
 {
-    calIIcalComponent parseICS(in AUTF8String serialized);
+    /**
+     * Parses an ICS string and uses the passed tzProvider instance to
+     * resolve timezones not contained withing the VCALENDAR.
+     *
+     * @param serialized     an ICS string
+     * @param tzProvider     timezone provider used to resolve TZIDs
+     *                       not contained within the VCALENDAR;
+     *                       if null is passed, parsing falls back to
+     *                       using the timezone service
+     */
+    calIIcalComponent parseICS(in AUTF8String serialized,
+                               in calITimezoneProvider tzProvider);
+
     calIIcalComponent createIcalComponent(in AUTF8String kind);
     calIIcalProperty createIcalProperty(in AUTF8String kind);
     /* I wish I could write this function atop libical!
     boolean isLegalParameterValue(in AUTF8String paramKind,
                                   in AUTF8String paramValue);
     */
-
-    /* Return a calIIcalComponent for the given timezone.  Note that
-     * the component returned is a VCALENDAR with a VTIMEZONE child,
-     * not the VTIMEZONE itself.
-     */
-    calIIcalComponent getTimezone(in AUTF8String tzid);
-    AUTF8String getTimezoneLatitude(in AUTF8String tzid);
-    AUTF8String getTimezoneLongitude(in AUTF8String tzid);
-
-    /**
-     * Adds and takes over ownership of a timezone record.
-     * Record will be ignored if there is already an existing one with the
-     * same id.
-     * 
-     * @param tzCal VCALENDAR with a VTIMEZONE child
-     * @param tzLatitude timzeone latitude, empty string if unknown
-     * @param tzLongitude timzeone longitude, empty string if unknown
-     * @return present VCALENDAR with a VTIMEZONE child
-     */
-    calIIcalComponent addTimezone(in calIIcalComponent tzCal,
-                                  in AUTF8String tzLatitude,
-                                  in AUTF8String tzLongitude);
-    
-    readonly attribute nsIUTF8StringEnumerator timezoneIds;
-
-    /**
-     * This is the string that is used to prefix all tzIds that come from our
-     * local tzid database.  This includes a trailing slash character.
-     */
-    readonly attribute AUTF8String tzIdPrefix;
-
-    /** 
-     * Takes a tzId, and if it's an old version of one of ours, returns 
-     * the current version of that tzId.  Otherwise returns the empty string.
-     *
-     * @param aTzId  the tzid to check
-     *
-     * @return       updated version of the same tzid or ""
-     */
-    AUTF8String latestTzId(in AUTF8String tzId);
 };
diff --git a/calendar/base/public/calIIcsParser.idl b/calendar/base/public/calIIcsParser.idl
index 19c75d8549d..f0d78312cd1 100644
--- a/calendar/base/public/calIIcsParser.idl
+++ b/calendar/base/public/calIIcsParser.idl
@@ -41,6 +41,7 @@ interface calIIcalProperty;
 interface calIIcalComponent;
 interface calIItemBase;
 interface nsIInputStream;
+interface calITimezoneProvider;
 
 /**
  * An interface for parsing an ics string or stream into its items.
@@ -56,8 +57,12 @@ interface calIIcsParser : nsISupports
    *
    * @param aICSString
    *    The ICS string to parse
+   * @param aTzProvider
+   *    The timezone provider used to resolve timezones not contained in the
+   *    parent VCALENDAR or null (falls back to timezone service)
    */
-  void parseString(in AString aICSString);
+    void parseString(in AString aICSString,
+                     in calITimezoneProvider aTzProvider);
 
   /**
    * Parse an input stream.
@@ -65,8 +70,12 @@ interface calIIcsParser : nsISupports
    * @see parseString
    * @param aICSString
    *    The stream to parse
+   * @param aTzProvider
+   *    The timezone provider used to resolve timezones not contained in the
+   *    parent VCALENDAR or null (falls back to timezone service)
    */
-  void parseFromStream(in nsIInputStream aStream);
+    void parseFromStream(in nsIInputStream aStream,
+                         in calITimezoneProvider aTzProvider);
 
   /**
    * Get the items that were in the string or stream
diff --git a/calendar/base/public/calITimezoneProvider.idl b/calendar/base/public/calITimezoneProvider.idl
new file mode 100644
index 00000000000..41ea4a1cc98
--- /dev/null
+++ b/calendar/base/public/calITimezoneProvider.idl
@@ -0,0 +1,121 @@
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is Sun Microsystems code.
+ *
+ * The Initial Developer of the Original Code is
+ * Sun Microsystems, Inc.
+ * Portions created by the Initial Developer are Copyright (C) 2007
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Daniel Boelzle <daniel.boelzle@sun.com>
+ *   Clint Talbert <ctalbert@mozilla.com>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#include "nsISupports.idl"
+
+interface calIIcalComponent;
+interface nsIUTF8StringEnumerator;
+interface calITimezoneProvider;
+
+[scriptable, uuid(D79161E7-0DB9-427d-A0C3-27E0DB3B030F)]
+interface calITimezone : nsISupports
+{
+    /**
+     * The timezone provider this timezone belongs to.
+     */
+    readonly attribute calITimezoneProvider provider;
+
+    /**
+     * VTIMEZONE ical component, null if floating.
+     */
+    readonly attribute calIIcalComponent component;
+
+    /**
+     * The TZID of this timezone.
+     */
+    readonly attribute AUTF8String tzid;
+
+    /**
+     * Whether this timezone is the "floating" timezone.
+     */
+    readonly attribute boolean isFloating;
+
+    /**
+     * Whether this is the "UTC" timezone.
+     */
+    readonly attribute boolean isUTC;
+
+    /**
+     * Latitude of timezone or empty string if unknown.
+     */
+    readonly attribute AUTF8String latitude;
+
+    /**
+     * Longitude of timezone or empty string if unknown.
+     */
+    readonly attribute AUTF8String longitude;
+
+    /**
+     * For debugging purposes.
+     *
+     * @return "UTC", "floating" or component's ical representation
+     */
+    AUTF8String toString();
+};
+
+[scriptable, uuid(0E502BF5-4FD3-4090-9122-F1EC3CA701BB)]
+interface calITimezoneProvider : nsISupports
+{
+    readonly attribute nsIUTF8StringEnumerator timezoneIds;
+
+    /**
+     * Gets a timezone defintion passing a TZID.
+     * Returns null in case of an unknown TZID.
+     *
+     * @param tzid       a TZID to be resolved
+     * @return           a timezone object or null
+     */
+    calITimezone getTimezone(in AUTF8String tzid);
+};
+
+/**
+ * This service acts as a central access point for the up to date set
+ * of Olson timezone definitions.
+ */
+[scriptable, uuid(AB1BFE6A-EE95-4038-B594-34AEEDA9911A)]
+interface calITimezoneService : calITimezoneProvider
+{
+    readonly attribute calITimezone floating;
+    readonly attribute calITimezone UTC;
+
+    /**
+     * This is the string that is used to prefix all tzIds that come from our
+     * local tzid database.  This includes a trailing slash character.
+     */
+    readonly attribute AUTF8String tzidPrefix;
+};
diff --git a/calendar/base/src/Makefile.in b/calendar/base/src/Makefile.in
index aa743b2d3f0..1afb8022678 100644
--- a/calendar/base/src/Makefile.in
+++ b/calendar/base/src/Makefile.in
@@ -69,6 +69,7 @@ CPPSRCS = calDateTime.cpp \
 	  calDuration.cpp \
 	  calPeriod.cpp \
 	  calICSService.cpp \
+	  calTimezoneService.cpp \
 	  calRecurrenceRule.cpp \
 	  calRecurrenceDate.cpp \
 	  calRecurrenceDateSet.cpp \
diff --git a/calendar/base/src/calAlarmService.js b/calendar/base/src/calAlarmService.js
index ecc38c57bde..f6e938806ab 100644
--- a/calendar/base/src/calAlarmService.js
+++ b/calendar/base/src/calAlarmService.js
@@ -39,6 +39,10 @@
 
 const kHoursBetweenUpdates = 6;
 
+function nowUTC() {
+    return jsDateToDateTime(new Date()).getInTimezone(UTC());
+}
+
 function newTimerWithCallback(callback, delay, repeating)
 {
     var timer = Components.classes["@mozilla.org/timer;1"].createInstance(Components.interfaces.nsITimer);
@@ -198,7 +202,7 @@ calAlarmService.prototype = {
     },
 
     set timezone(aTimezone) {
-        this.mTimezone = aTimezone;
+        return (this.mTimezone = aTimezone);
     },
 
     snoozeAlarm: function cas_snoozeAlarm(event, duration) {
@@ -206,7 +210,7 @@ calAlarmService.prototype = {
         // Make sure we're working with the parent, otherwise we'll accidentally
         // create an exception
         var newEvent = event.parentItem.clone();
-        var alarmTime = jsDateToDateTime((new Date())).getInTimezone("UTC");
+        var alarmTime = nowUTC();
 
         // Set the last acknowledged time to now.
         newEvent.alarmLastAck = alarmTime;
@@ -230,7 +234,7 @@ calAlarmService.prototype = {
     },
 
     dismissAlarm: function cas_dismissAlarm(item) {
-        var now = jsDateToDateTime(new Date()).getInTimezone("UTC");
+        var now = nowUTC();
         // We want the parent item, otherwise we're going to accidentally create an
         // exception.  We've relnoted (for 0.1) the slightly odd behavior this can
         // cause if you move an event after dismissing an alarm
@@ -296,7 +300,7 @@ calAlarmService.prototype = {
         var timerCallback = {
             alarmService: this,
             notify: function timer_notify() {
-                var now = jsDateToDateTime((new Date())).getInTimezone("UTC");
+                var now = nowUTC();
                 var start;
                 if (!this.alarmService.mRangeEnd) {
                     // This is our first search for alarms.  We're going to look for
@@ -315,7 +319,7 @@ calAlarmService.prototype = {
                 // We don't set timers for every future alarm, only those within 6 hours
                 var end = now.clone();
                 end.hour += kHoursBetweenUpdates;
-                this.alarmService.mRangeEnd = end.getInTimezone("UTC");
+                this.alarmService.mRangeEnd = end.getInTimezone(UTC());
 
                 this.alarmService.findAlarms(this.alarmService.calendarManager.getCalendars({}),
                                              start, until);
@@ -400,14 +404,14 @@ calAlarmService.prototype = {
         // a well defined startTime.  We just consider the start/end to be
         // midnight in the user's timezone.
         if (alarmDate.isDate) {
-            alarmDate = alarmDate.getInTimezone(this.mTimezone);
+            alarmDate = alarmDate.getInTimezone(this.timezone);
             alarmDate.isDate = false;
         }
 
         var offset = aItem.alarmOffset || aItem.parentItem.alarmOffset;
 
         alarmDate.addDuration(offset);
-        alarmDate = alarmDate.getInTimezone("UTC");
+        alarmDate = alarmDate.getInTimezone(UTC());
 
         return alarmDate;
     },
@@ -439,12 +443,12 @@ calAlarmService.prototype = {
         // If the alarm was snoozed, the snooze time is more important.
         alarmTime = snoozeTime || alarmTime;
 
-        var now = jsDateToDateTime((new Date()));
-        if (alarmTime.timezone == "floating") {
+        var now = jsDateToDateTime(new Date());
+        if (alarmTime.timezone.isFloating) {
             now = now.getInTimezone(calendarDefaultTimezone());
-            now.timezone = "floating";
+            now.timezone = floating();
         } else {
-            now = now.getInTimezone("UTC");
+            now = now.getInTimezone(UTC());
         }
         LOG("[calAlarmService] now is " + now);
         var callbackObj = {
@@ -514,7 +518,7 @@ calAlarmService.prototype = {
             cal[aItem.id] = itemTimers;
         }
         var rid = aItem.recurrenceId;
-        itemTimers[rid ? rid.getInTimezone("UTC").icalString : "mTimer"] = aTimer;
+        itemTimers[rid ? rid.getInTimezone(UTC()).icalString : "mTimer"] = aTimer;
         ++itemTimers.mCount;
     },
 
@@ -525,7 +529,7 @@ calAlarmService.prototype = {
             if (itemTimers) {
                 var rid = aItem.recurrenceId;
                 if (rid) {
-                    rid = rid.getInTimezone("UTC").icalString;
+                    rid = rid.getInTimezone(UTC()).icalString;
                     var timer = itemTimers[rid];
                     if (timer) {
                         delete itemTimers[rid];
@@ -580,7 +584,7 @@ calAlarmService.prototype = {
         // alarms +/- 1 month from now.  If someone sets an alarm more than
         // a month ahead of an event, or doesn't start Sunbird/Lightning
         // for a month, they'll miss some, but that's a slim chance
-        var start = jsDateToDateTime((new Date())).getInTimezone("UTC");
+        var start = nowUTC();
         var until = start.clone();
         start.month -= 1;
         until.month += 1;
diff --git a/calendar/base/src/calAttributeHelpers.h b/calendar/base/src/calAttributeHelpers.h
index 233c3a5b645..aa69d5418ea 100644
--- a/calendar/base/src/calAttributeHelpers.h
+++ b/calendar/base/src/calAttributeHelpers.h
@@ -39,8 +39,12 @@
 #ifndef CALATTRIBUTEHELPERS_H_
 #define CALATTRIBUTEHELPERS_H_
 
-#ifndef UPDATE_LAST_MODIFIED
-#define UPDATE_LAST_MODIFIED /**/
+#ifndef CAL_ATTR_SET_PRE
+#define CAL_ATTR_SET_PRE /**/
+#endif
+
+#ifndef CAL_ATTR_SET_POST
+#define CAL_ATTR_SET_POST /**/
 #endif
 
 /**
@@ -59,9 +63,9 @@ cname::Get##name (mtype &_retval) { \
 #define CAL_STRINGTYPE_ATTR_SETTER(cname,mtype,name) \
 NS_IMETHODIMP \
 cname::Set##name (const mtype &aValue) { \
-    if (mImmutable) return NS_ERROR_OBJECT_IS_IMMUTABLE; \
+    CAL_ATTR_SET_PRE; \
     m##name.Assign(aValue); \
-    UPDATE_LAST_MODIFIED; \
+    CAL_ATTR_SET_POST; \
     return NS_OK; \
 }
 
@@ -73,6 +77,7 @@ cname::Set##name (const mtype &aValue) { \
 #define CAL_VALUETYPE_ATTR_GETTER(cname,mtype,name) \
 NS_IMETHODIMP \
 cname::Get##name (mtype *_retval) { \
+    NS_ENSURE_ARG_POINTER(_retval); \
     *_retval = m##name; \
     return NS_OK; \
 }
@@ -80,10 +85,10 @@ cname::Get##name (mtype *_retval) { \
 #define CAL_VALUETYPE_ATTR_SETTER(cname,mtype,name) \
 NS_IMETHODIMP \
 cname::Set##name (mtype aValue) { \
-    if (mImmutable) return NS_ERROR_OBJECT_IS_IMMUTABLE; \
+    CAL_ATTR_SET_PRE; \
     if (m##name != aValue) { \
         m##name = aValue; \
-        UPDATE_LAST_MODIFIED; \
+        CAL_ATTR_SET_POST; \
     } \
     return NS_OK; \
 }
@@ -96,6 +101,7 @@ cname::Set##name (mtype aValue) { \
 #define CAL_ISUPPORTS_ATTR_GETTER(cname,mtype,name) \
 NS_IMETHODIMP \
 cname::Get##name (mtype **_retval) { \
+    NS_ENSURE_ARG_POINTER(_retval); \
     NS_IF_ADDREF (*_retval = m##name); \
     return NS_OK; \
 }
@@ -103,10 +109,10 @@ cname::Get##name (mtype **_retval) { \
 #define CAL_ISUPPORTS_ATTR_SETTER(cname,mtype,name) \
 NS_IMETHODIMP \
 cname::Set##name (mtype *aValue) { \
-    if (mImmutable) return NS_ERROR_OBJECT_IS_IMMUTABLE; \
+    CAL_ATTR_SET_PRE; \
     if (m##name != aValue) { \
         m##name = aValue; \
-        UPDATE_LAST_MODIFIED; \
+        CAL_ATTR_SET_POST; \
     } \
     return NS_OK; \
 }
diff --git a/calendar/base/src/calDateTime.cpp b/calendar/base/src/calDateTime.cpp
index 98ce88b1b16..ae84bf9fbe7 100644
--- a/calendar/base/src/calDateTime.cpp
+++ b/calendar/base/src/calDateTime.cpp
@@ -1,4 +1,3 @@
-/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
@@ -48,7 +47,6 @@
 #include "nsIClassInfoImpl.h"
 #endif
 
-#include "calIICSService.h"
 #include "calIErrors.h"
 #include "calDuration.h"
 
@@ -56,41 +54,25 @@
 #include "prprf.h"
 
 extern "C" {
-    #include "ical.h"
+#include "ical.h"
 }
 
-#define UPDATE_LAST_MODIFIED normalize()
+#define CAL_ATTR_SET_PRE NS_ENSURE_FALSE(mImmutable, NS_ERROR_OBJECT_IS_IMMUTABLE)
+#define CAL_ATTR_SET_POST Normalize()
 #include "calAttributeHelpers.h"
 
-static NS_DEFINE_CID(kCalICSService, CAL_ICSSERVICE_CID);
-
 NS_IMPL_ISUPPORTS2_CI(calDateTime, calIDateTime, nsIXPCScriptable)
 
-calDateTime::calDateTime() : mImmutable(PR_FALSE)
+calDateTime::calDateTime()
+    : mImmutable(PR_FALSE)
 {
     Reset();
 }
 
-calDateTime::calDateTime(struct icaltimetype const* atimeptr) : mImmutable(PR_FALSE)
-{
-    FromIcalTime(atimeptr);
-}
-
-calDateTime::calDateTime(const calDateTime& cdt)
-    : mImmutable(PR_FALSE),
-      mIsValid(cdt.mIsValid),
-      mNativeTime(cdt.mNativeTime),
-      mYear(cdt.mYear),
-      mMonth(cdt.mMonth),
-      mDay(cdt.mDay),
-      mHour(cdt.mHour),
-      mMinute(cdt.mMinute),
-      mSecond(cdt.mSecond),
-      mWeekday(cdt.mWeekday),
-      mYearday(cdt.mYearday),
-      mIsDate(cdt.mIsDate),
-      mTimezone(cdt.mTimezone)
+calDateTime::calDateTime(icaltimetype const* atimeptr, calITimezone *tz)
+    : mImmutable(PR_FALSE)
 {
+    FromIcalTime(atimeptr, tz);
 }
 
 NS_IMETHODIMP
@@ -112,9 +94,10 @@ NS_IMETHODIMP
 calDateTime::Clone(calIDateTime **aResult)
 {
     NS_ENSURE_ARG_POINTER(aResult);
-    calDateTime *cdt = new calDateTime(*this);
-    if (!cdt)
-        return NS_ERROR_OUT_OF_MEMORY;
+    icaltimetype itt;
+    ToIcalTime(&itt);
+    calDateTime * const cdt = new calDateTime(&itt, mTimezone);
+    CAL_ENSURE_MEMORY(cdt);
     NS_ADDREF(*aResult = cdt);
     return NS_OK;
 }
@@ -126,28 +109,26 @@ calDateTime::ResetTo(PRInt16 year,
                      PRInt16 hour,
                      PRInt16 minute,
                      PRInt16 second,
-                     nsACString const& timezone)
+                     calITimezone * tz)
 {
-    nsresult rc = SetTimezone(timezone);
-    if (NS_SUCCEEDED(rc)) {
-        mYear = year;
-        mMonth = month;
-        mDay = day;
-        mHour = hour;
-        mMinute = minute;
-        mSecond = second;
-        mIsDate = PR_FALSE;
-        normalize();
-    }
-    return rc;
+    NS_ENSURE_FALSE(mImmutable, NS_ERROR_OBJECT_IS_IMMUTABLE);
+    NS_ENSURE_ARG_POINTER(tz);
+    mYear = year;
+    mMonth = month;
+    mDay = day;
+    mHour = hour;
+    mMinute = minute;
+    mSecond = second;
+    mIsDate = PR_FALSE;
+    mTimezone = tz;
+    Normalize();
+    return NS_OK;
 }
 
 NS_IMETHODIMP
 calDateTime::Reset()
 {
-    if (mImmutable)
-        return NS_ERROR_OBJECT_IS_IMMUTABLE;
-
+    NS_ENSURE_FALSE(mImmutable, NS_ERROR_OBJECT_IS_IMMUTABLE);
     mYear = 1970;
     mMonth = 0;
     mDay = 1;
@@ -157,123 +138,56 @@ calDateTime::Reset()
     mWeekday = 4;
     mYearday = 1;
     mIsDate = PR_FALSE;
-    mTimezone.AssignLiteral("UTC");
+    cal::getTimezoneService()->GetUTC(getter_AddRefs(mTimezone));
     mNativeTime = 0;
-
     mIsValid = PR_TRUE;
     return NS_OK;
 }
 
-CAL_VALUETYPE_ATTR_GETTER(calDateTime, PRBool, IsValid)
-
 CAL_VALUETYPE_ATTR(calDateTime, PRInt16, Year)
 CAL_VALUETYPE_ATTR(calDateTime, PRInt16, Month)
 CAL_VALUETYPE_ATTR(calDateTime, PRInt16, Day)
 CAL_VALUETYPE_ATTR(calDateTime, PRInt16, Hour)
 CAL_VALUETYPE_ATTR(calDateTime, PRInt16, Minute)
 CAL_VALUETYPE_ATTR(calDateTime, PRInt16, Second)
-
+CAL_VALUETYPE_ATTR(calDateTime, PRBool, IsDate)
+CAL_ISUPPORTS_ATTR(calDateTime, calITimezone, Timezone)
+CAL_VALUETYPE_ATTR_GETTER(calDateTime, PRBool, IsValid)
+CAL_VALUETYPE_ATTR_GETTER(calDateTime, PRTime, NativeTime)
 CAL_VALUETYPE_ATTR_GETTER(calDateTime, PRInt16, Weekday)
 CAL_VALUETYPE_ATTR_GETTER(calDateTime, PRInt16, Yearday)
 
-CAL_STRINGTYPE_ATTR_GETTER(calDateTime, nsACString, Timezone)
-
-NS_IMETHODIMP
-calDateTime::SetIsDate(PRBool aIsDate)
-{
-    if (mImmutable)
-        return NS_ERROR_OBJECT_IS_IMMUTABLE;
-
-    if (mIsDate != aIsDate) {
-        mIsDate = aIsDate;
-        if (aIsDate) {
-            mHour = 0;
-            mMinute = 0;
-            mSecond = 0;
-        }
-        normalize();
-    }
-    return NS_OK;
-}
-
-NS_IMETHODIMP
-calDateTime::GetIsDate(PRBool *aResult)
-{
-    NS_ENSURE_ARG_POINTER(aResult);
-    *aResult = mIsDate;
-    return NS_OK;
-}
-
-NS_IMETHODIMP
-calDateTime::SetTimezone(const nsACString& aTimezone)
-{
-    if (mImmutable)
-        return NS_ERROR_OBJECT_IS_IMMUTABLE;
-    if (aTimezone.EqualsLiteral("UTC") || aTimezone.EqualsLiteral("utc")) {
-        mTimezone.AssignLiteral("UTC");
-    } else if (aTimezone.EqualsLiteral("floating")) {
-        mTimezone.AssignLiteral("floating");
-    } else {
-        icaltimezone const* tz = nsnull;
-        nsresult rv = GetIcalTZ(aTimezone, &tz);
-        if (NS_FAILED(rv))
-            return rv;
-        mTimezone.Assign(aTimezone);
-    }
-    normalize();
-    return NS_OK;
-}
-
 NS_IMETHODIMP
 calDateTime::GetTimezoneOffset(PRInt32 *aResult)
 {
     NS_ENSURE_ARG_POINTER(aResult);
-    struct icaltimetype icalt;
+    icaltimetype icalt;
     ToIcalTime(&icalt);
     int dst;
-    *aResult = icaltimezone_get_utc_offset(
-        const_cast<icaltimezone *>(icalt.zone), &icalt, &dst);
-    return NS_OK;
-}
-
-NS_IMETHODIMP
-calDateTime::GetNativeTime(PRTime *aResult)
-{
-    NS_ENSURE_ARG_POINTER(aResult);
-    *aResult = mNativeTime;
+    *aResult = icaltimezone_get_utc_offset(const_cast<icaltimezone *>(icalt.zone), &icalt, &dst);
     return NS_OK;
 }
 
 NS_IMETHODIMP
 calDateTime::SetNativeTime(PRTime aNativeTime)
 {
-    return SetTimeInTimezone (aNativeTime, NS_LITERAL_CSTRING("UTC"));
-}
-
-// internal normalize():
-void calDateTime::normalize()
-{
-    struct icaltimetype icalt;
-    ToIcalTime(&icalt);
-    FromIcalTime(&icalt);
+    return SetTimeInTimezone(aNativeTime, cal::UTC());
 }
 
 NS_IMETHODIMP
 calDateTime::AddDuration(calIDuration *aDuration)
 {
+    NS_ENSURE_FALSE(mImmutable, NS_ERROR_OBJECT_IS_IMMUTABLE);
     NS_ENSURE_ARG_POINTER(aDuration);
-    if (mImmutable)
-        return NS_ERROR_OBJECT_IS_IMMUTABLE;
 
-    struct icaldurationtype idt;
+    icaldurationtype idt;
     aDuration->ToIcalDuration(&idt);
     
-    struct icaltimetype itt;
+    icaltimetype itt;
     ToIcalTime(&itt);
 
-    struct icaltimetype newitt;
-    newitt = icaltime_add(itt, idt);
-    FromIcalTime(&newitt);
+    icaltimetype const newitt = icaltime_add(itt, idt);
+    FromIcalTime(&newitt, mTimezone);
 
     return NS_OK;
 }
@@ -292,217 +206,174 @@ calDateTime::SubtractDate(calIDateTime *aDate, calIDuration **aDuration)
     icaldurationtype const idt = icaldurationtype_from_int(
         static_cast<int>((mNativeTime - t2t) / PRInt64(PR_USEC_PER_SEC)));
 
-    nsCOMPtr<calIDuration> const result(new calDuration(&idt));
-    if (!result)
-        return NS_ERROR_OUT_OF_MEMORY;
-
-    *aDuration = result;
-    NS_ADDREF(*aDuration);
-
+    calDuration * const dur = new calDuration(&idt);
+    CAL_ENSURE_MEMORY(dur);
+    NS_ADDREF(*aDuration = dur);
     return NS_OK;
 }
 
 NS_IMETHODIMP
-calDateTime::ToString(nsACString& aResult)
+calDateTime::ToString(nsACString & aResult)
 {
+    nsCAutoString tzid;
+    mTimezone->GetTzid(tzid);
     char buffer[256];
     PRUint32 const length = PR_snprintf(
         buffer, sizeof(buffer), "%04hd/%02hd/%02hd %02hd:%02hd:%02hd %s isDate=%01hd",
         mYear, mMonth + 1, mDay, mHour, mMinute, mSecond,
-        mTimezone.get(), static_cast<PRInt16>(mIsDate));
+        tzid.get(), static_cast<PRInt16>(mIsDate));
     if (length != static_cast<PRUint32>(-1))
         aResult.Assign(buffer, length);
     return NS_OK;
 }
 
 NS_IMETHODIMP
-calDateTime::SetTimeInTimezone(PRTime aTime, const nsACString& aTimezone)
+calDateTime::SetTimeInTimezone(PRTime aTime, calITimezone * aTimezone)
 {
-    if (mImmutable)
-        return NS_ERROR_OBJECT_IS_IMMUTABLE;
-    if (aTimezone.IsEmpty())
-        return NS_ERROR_INVALID_ARG;
-
-    icaltimezone const* tz = nsnull;
-    nsresult rv = GetIcalTZ(aTimezone, &tz);
-    NS_ENSURE_SUCCESS(rv, rv);
-
-    struct icaltimetype icalt = icaltime_null_time();
-    PRTimeToIcaltime(aTime, PR_FALSE, tz, &icalt);
-
-    FromIcalTime(&icalt);
-
+    NS_ENSURE_FALSE(mImmutable, NS_ERROR_OBJECT_IS_IMMUTABLE);
+    NS_ENSURE_ARG_POINTER(aTimezone);
+    icaltimetype icalt;
+    PRTimeToIcaltime(aTime, PR_FALSE, cal::getIcalTimezone(aTimezone), &icalt);
+    FromIcalTime(&icalt, aTimezone);
     return NS_OK;
 }
 
 NS_IMETHODIMP
-calDateTime::GetInTimezone(const nsACString& aTimezone, calIDateTime **aResult)
+calDateTime::GetInTimezone(calITimezone * aTimezone, calIDateTime ** aResult)
 {
+    NS_ENSURE_ARG_POINTER(aTimezone);
     NS_ENSURE_ARG_POINTER(aResult);
 
-    calDateTime *cdt = nsnull;
-
     if (mIsDate) {
         // if it's a date, we really just want to make a copy of this
         // and set the timezone.
-        cdt = new calDateTime(*this);
-        cdt->mTimezone.Assign(aTimezone);
-    } else if (mTimezone.Equals(aTimezone)) {
-        cdt = new calDateTime(*this);
+        nsresult rv = Clone(aResult);
+        if (NS_SUCCEEDED(rv)) {
+            rv = (*aResult)->SetTimezone(aTimezone);
+        }
+        return rv;
     } else {
-        struct icaltimetype icalt;
-        icaltimezone const* tz = nsnull;
-
+        icaltimetype icalt;
         ToIcalTime(&icalt);
 
-        // Get the latest version of aTimezone.
-        nsresult rv;
-
-        nsCOMPtr<calIICSService> const icsSvc(do_GetService(kCalICSService, &rv));
-        if (NS_FAILED(rv)) {
-            return rv;
+        icaltimezone * tz = cal::getIcalTimezone(aTimezone);
+        if (icalt.zone == tz) {
+            return Clone(aResult);
         }
 
-        nsCAutoString newTimezone;
-        rv = icsSvc->LatestTzId(aTimezone, newTimezone);
-        if (NS_FAILED(rv)) {
-            return rv;
-        }
-
-        if (newTimezone.Length() == 0) {
-            newTimezone = aTimezone;
-        }
-
-        rv = GetIcalTZ(newTimezone, &tz);
-        if (NS_FAILED(rv))
-            return rv;
-
         /* If there's a zone, we need to convert; otherwise, we just
          * assign, since this item is floating */
         if (icalt.zone && tz) {
-            icaltimezone_convert_time(&icalt,
-                                      const_cast<icaltimezone *>(icalt.zone),
-                                      const_cast<icaltimezone *>(tz));
+            icaltimezone_convert_time(&icalt, const_cast<icaltimezone *>(icalt.zone), tz);
         }
-        if (tz == icaltimezone_get_utc_timezone())
-            icalt.is_utc = 1;
-        else
-            icalt.is_utc = 0;
         icalt.zone = tz;
+        icalt.is_utc = (tz && tz == icaltimezone_get_utc_timezone());
 
-        cdt = new calDateTime(&icalt);
+        calDateTime * cdt = new calDateTime(&icalt, aTimezone);
+        CAL_ENSURE_MEMORY(cdt);
+        NS_ADDREF (*aResult = cdt);
+        return NS_OK;
     }
-
-    if (!cdt)
-        return NS_ERROR_OUT_OF_MEMORY;
-    NS_ADDREF (*aResult = cdt);
-    return NS_OK;
 }
 
 NS_IMETHODIMP
-calDateTime::GetStartOfWeek(calIDateTime **aResult)
+calDateTime::GetStartOfWeek(calIDateTime ** aResult)
 {
     NS_ENSURE_ARG_POINTER(aResult);
 
-    struct icaltimetype icalt;
+    icaltimetype icalt;
     ToIcalTime(&icalt);
     int day_of_week = icaltime_day_of_week(icalt);
     if (day_of_week > 1)
         icaltime_adjust(&icalt, - (day_of_week - 1), 0, 0, 0);
     icalt.is_date = 1;
 
-    calDateTime *cdt = new calDateTime(&icalt);
-    if (!cdt)
-        return NS_ERROR_OUT_OF_MEMORY;
+    calDateTime * const cdt = new calDateTime(&icalt, mTimezone);
+    CAL_ENSURE_MEMORY(cdt);
     NS_ADDREF(*aResult = cdt);
     return NS_OK;
 }
 
 NS_IMETHODIMP
-calDateTime::GetEndOfWeek(calIDateTime **aResult)
+calDateTime::GetEndOfWeek(calIDateTime ** aResult)
 {
     NS_ENSURE_ARG_POINTER(aResult);
 
-    struct icaltimetype icalt;
+    icaltimetype icalt;
     ToIcalTime(&icalt);
     int day_of_week = icaltime_day_of_week(icalt);
     if (day_of_week < 7)
         icaltime_adjust(&icalt, 7 - day_of_week, 0, 0, 0);
     icalt.is_date = 1;
 
-    calDateTime *cdt = new calDateTime(&icalt);
-    if (!cdt)
-        return NS_ERROR_OUT_OF_MEMORY;
+    calDateTime * const cdt = new calDateTime(&icalt, mTimezone);
+    CAL_ENSURE_MEMORY(cdt);
     NS_ADDREF(*aResult = cdt);
     return NS_OK;
 }
 
 NS_IMETHODIMP
-calDateTime::GetStartOfMonth(calIDateTime **aResult)
+calDateTime::GetStartOfMonth(calIDateTime ** aResult)
 {
     NS_ENSURE_ARG_POINTER(aResult);
 
-    struct icaltimetype icalt;
+    icaltimetype icalt;
     ToIcalTime(&icalt);
     icalt.day = 1;
     icalt.is_date = 1;
 
-    calDateTime *cdt = new calDateTime(&icalt);
-    if (!cdt)
-        return NS_ERROR_OUT_OF_MEMORY;
+    calDateTime * const cdt = new calDateTime(&icalt, mTimezone);
+    CAL_ENSURE_MEMORY(cdt);
     NS_ADDREF(*aResult = cdt);
     return NS_OK;
 }
 
 NS_IMETHODIMP
-calDateTime::GetEndOfMonth(calIDateTime **aResult)
+calDateTime::GetEndOfMonth(calIDateTime ** aResult)
 {
     NS_ENSURE_ARG_POINTER(aResult);
 
-    struct icaltimetype icalt;
+    icaltimetype icalt;
     ToIcalTime(&icalt);
     icalt.day = icaltime_days_in_month(icalt.month, icalt.year);
     icalt.is_date = 1;
 
-    calDateTime *cdt = new calDateTime(&icalt);
-    if (!cdt)
-        return NS_ERROR_OUT_OF_MEMORY;
+    calDateTime * const cdt = new calDateTime(&icalt, mTimezone);
+    CAL_ENSURE_MEMORY(cdt);
     NS_ADDREF(*aResult = cdt);
     return NS_OK;
 }
 
 NS_IMETHODIMP
-calDateTime::GetStartOfYear(calIDateTime **aResult)
+calDateTime::GetStartOfYear(calIDateTime ** aResult)
 {
     NS_ENSURE_ARG_POINTER(aResult);
 
-    struct icaltimetype icalt;
+    icaltimetype icalt;
     ToIcalTime(&icalt);
     icalt.month = 1;
     icalt.day = 1;
     icalt.is_date = 1;
 
-    calDateTime *cdt = new calDateTime(&icalt);
-    if (!cdt)
-        return NS_ERROR_OUT_OF_MEMORY;
+    calDateTime * const cdt = new calDateTime(&icalt, mTimezone);
+    CAL_ENSURE_MEMORY(cdt);
     NS_ADDREF(*aResult = cdt);
     return NS_OK;
 }
 
 NS_IMETHODIMP
-calDateTime::GetEndOfYear(calIDateTime **aResult)
+calDateTime::GetEndOfYear(calIDateTime ** aResult)
 {
     NS_ENSURE_ARG_POINTER(aResult);
 
-    struct icaltimetype icalt;
+    icaltimetype icalt;
     ToIcalTime(&icalt);
     icalt.month = 12;
     icalt.day = 31;
     icalt.is_date = 1;
 
-    calDateTime *cdt = new calDateTime(&icalt);
-    if (!cdt)
-        return NS_ERROR_OUT_OF_MEMORY;
+    calDateTime * const cdt = new calDateTime(&icalt, mTimezone);
+    CAL_ENSURE_MEMORY(cdt);
     NS_ADDREF(*aResult = cdt);
     return NS_OK;
 }
@@ -514,27 +385,22 @@ calDateTime::GetIcalString(nsACString& aResult)
     ToIcalTime(&t);
 
     // note that ics is owned by libical, so we don't need to free
-    const char *ics = icaltime_as_ical_string(t);
-    
-    if (ics) {
-        aResult.Assign(ics);
-        return NS_OK;
-    }
-
-    return NS_ERROR_OUT_OF_MEMORY;
+    char const * const ics = icaltime_as_ical_string(t);
+    CAL_ENSURE_MEMORY(ics);
+    aResult.Assign(ics);
+    return NS_OK;
 }
 
 NS_IMETHODIMP
-calDateTime::SetIcalString(const nsACString& aIcalString)
+calDateTime::SetIcalString(nsACString const& aIcalString)
 {
-    if (mImmutable)
-        return NS_ERROR_OBJECT_IS_IMMUTABLE;
-    struct icaltimetype icalt;
-    icalt = icaltime_from_string(nsPromiseFlatCString(aIcalString).get());
+    NS_ENSURE_FALSE(mImmutable, NS_ERROR_OBJECT_IS_IMMUTABLE);
+    icaltimetype icalt;
+    icalt = icaltime_from_string(PromiseFlatCString(aIcalString).get());
     if (icaltime_is_null_time(icalt)) {
         return calIErrors::ICS_ERROR_BASE + icalerrno;
     }
-    FromIcalTime(&icalt);
+    FromIcalTime(&icalt, mTimezone);
     return NS_OK;
 }
 
@@ -542,8 +408,16 @@ calDateTime::SetIcalString(const nsACString& aIcalString)
  ** utility/protected methods
  **/
 
+// internal Normalize():
+void calDateTime::Normalize()
+{
+    icaltimetype icalt;
+    ToIcalTime(&icalt);
+    FromIcalTime(&icalt, mTimezone);
+}
+
 NS_IMETHODIMP_(void)
-calDateTime::ToIcalTime(icaltimetype *icalt)
+calDateTime::ToIcalTime(struct icaltimetype * icalt)
 {
     icalt->year = mYear;
     icalt->month = mMonth + 1;
@@ -555,25 +429,17 @@ calDateTime::ToIcalTime(icaltimetype *icalt)
     icalt->is_date = mIsDate ? 1 : 0;
     icalt->is_daylight = 0;
 
-    icaltimezone const* tz = nsnull;
-    nsresult rv = GetIcalTZ(mTimezone, &tz);
-    // this will always succeed, because
-    // mTimezone can't be set without GetIcalTZ
-    // succeeding.
-    if (NS_FAILED(rv)) {
-        NS_ERROR("calDateTime::ToIcalTime: GetIcalTZ failed!");
-    }
-
+    icaltimezone * tz = cal::getIcalTimezone(mTimezone);
     icalt->zone = tz;
-
-    if (icalt->zone == icaltimezone_get_utc_timezone())
-        icalt->is_utc = 1;
-    else
-        icalt->is_utc = 0;
+    icalt->is_utc = (tz && tz == icaltimezone_get_utc_timezone());
+    icalt->is_daylight = 0;
+    // xxx todo: discuss/investigate is_daylight
+//     if (tz) {
+//         icaltimezone_get_utc_offset(tz, icalt, &icalt->is_daylight);
+//     }
 }
 
-void
-calDateTime::FromIcalTime(icaltimetype const* icalt)
+void calDateTime::FromIcalTime(icaltimetype const* icalt, calITimezone * tz)
 {
     icaltimetype t = *icalt;
     mIsValid = (icaltime_is_null_time(t) ||
@@ -597,18 +463,31 @@ calDateTime::FromIcalTime(icaltimetype const* icalt)
     mMinute = t.minute;
     mSecond = t.second;
 
-    if (t.is_utc || t.zone == icaltimezone_get_utc_timezone()) {
-        mTimezone.AssignLiteral("UTC");
-    } else if (t.zone) {
-        mTimezone.Assign(icaltimezone_get_tzid(
-                             const_cast<icaltimezone *>(t.zone)));
+    if (tz) {
+        mTimezone = tz;
     } else {
-        mTimezone.AssignLiteral("floating");
+        mTimezone = cal::detectTimezone(t, nsnull);
     }
+#if defined(DEBUG)
+    if (mTimezone) {
+        if (t.is_utc) {
+            NS_ASSERTION(cal::sameXpcomObject(mTimezone, cal::UTC()),
+                         "UTC mismatch!");
+        } else if (!t.zone) {
+            NS_ASSERTION(cal::sameXpcomObject(mTimezone, cal::floating()),
+                         "floating mismatch!");
+        } else {
+            nsCAutoString tzid;
+            mTimezone->GetTzid(tzid);
+            NS_ASSERTION(tzid.Equals(icaltimezone_get_tzid(const_cast<icaltimezone *>(t.zone))),
+                         "tzid mismatch!");
+        }
+    }
+#endif
 
     mWeekday = icaltime_day_of_week(t) - 1;
     mYearday = icaltime_day_of_year(t);
-    
+
     // mNativeTime: not moving the existing date to UTC,
     // but merely representing it a UTC-based way.
     t.is_date = 0;
@@ -617,8 +496,8 @@ calDateTime::FromIcalTime(icaltimetype const* icalt)
 
 PRTime calDateTime::IcaltimeToPRTime(icaltimetype const* icalt, icaltimezone const* tz)
 {
-    struct icaltimetype tt;
-    struct PRExplodedTime et;
+    icaltimetype tt;
+    PRExplodedTime et;
 
     /* If the time is the special null time, return 0. */
     if (icaltime_is_null_time(*icalt)) {
@@ -653,11 +532,9 @@ PRTime calDateTime::IcaltimeToPRTime(icaltimetype const* icalt, icaltimezone con
 
 void calDateTime::PRTimeToIcaltime(PRTime time, PRBool isdate,
                                    icaltimezone const* tz,
-                                   icaltimetype *icalt)
+                                   icaltimetype * icalt)
 {
-    icaltimezone *utc_zone;
-
-    struct PRExplodedTime et;
+    PRExplodedTime et;
     PR_ExplodeTime(time, PR_GMTParameters, &et);
 
     icalt->year   = et.tm_year;
@@ -665,24 +542,28 @@ void calDateTime::PRTimeToIcaltime(PRTime time, PRBool isdate,
     icalt->day    = et.tm_mday;
 
     if (isdate) { 
+        icalt->hour    = 0;
+        icalt->minute  = 0;
+        icalt->second  = 0;
         icalt->is_date = 1;
-        return;
+    } else {
+        icalt->hour   = et.tm_hour;
+        icalt->minute = et.tm_min;
+        icalt->second = et.tm_sec;
+        icalt->is_date = 0;
     }
 
-    icalt->hour   = et.tm_hour;
-    icalt->minute = et.tm_min;
-    icalt->second = et.tm_sec;
-
-    /* Only do conversion when not in floating timezone */
-    if (tz) {
-        utc_zone = icaltimezone_get_utc_timezone();
-        icalt->is_utc = (tz == utc_zone) ? 1 : 0;
-        icalt->zone = tz;
-    }
+    icalt->zone = tz;
+    icalt->is_utc = ((tz && tz == icaltimezone_get_utc_timezone()) ? 1 : 0);
+    icalt->is_daylight = 0;
+    // xxx todo: discuss/investigate is_daylight
+//     if (tz) {
+//         icaltimezone_get_utc_offset(tz, icalt, &icalt->is_daylight);
+//     }
 }
 
 NS_IMETHODIMP
-calDateTime::Compare(calIDateTime *aOther, PRInt32 *aResult)
+calDateTime::Compare(calIDateTime * aOther, PRInt32 * aResult)
 {
     NS_ENSURE_ARG_POINTER(aOther);
     NS_ENSURE_ARG_POINTER(aResult);
@@ -704,13 +585,7 @@ calDateTime::Compare(calIDateTime *aOther, PRInt32 *aResult)
     }
 
     if (mIsDate || otherIsDate) {
-        icaltimezone const* tz;
-        nsresult rv = GetIcalTZ(mTimezone, &tz);
-        if (NS_FAILED(rv))
-            return calIErrors::INVALID_TIMEZONE;
-
-        *aResult = icaltime_compare_date_only(a, b,
-                                              const_cast<icaltimezone *>(tz));
+        *aResult = icaltime_compare_date_only(a, b, cal::getIcalTimezone(mTimezone));
     } else {
         *aResult = icaltime_compare(a, b);
     }
@@ -718,62 +593,23 @@ calDateTime::Compare(calIDateTime *aOther, PRInt32 *aResult)
     return NS_OK;
 }
 
-nsresult calDateTime::GetIcalTZ(nsACString const& tzid, icaltimezone const** tzp)
-{
-    if (tzid.IsEmpty()) {
-        return NS_ERROR_INVALID_ARG;
-    }
-
-    if (tzid.EqualsLiteral("floating")) {
-        *tzp = nsnull;
-        return NS_OK;
-    }
-
-    if (tzid.EqualsLiteral("UTC") || tzid.EqualsLiteral("utc")) {
-        *tzp = icaltimezone_get_utc_timezone();
-        return NS_OK;
-    }
-
-    nsCOMPtr<calIICSService> const ics(do_GetService(kCalICSService));
-    nsCOMPtr<calIIcalComponent> tz;
-
-    nsresult rv = ics->GetTimezone(tzid, getter_AddRefs(tz));
-    if (NS_FAILED(rv) || !tz) {
-        // No timezone was found. To prevent the app from dying,
-        // pretent that there is no timezone, ie return floating.
-        // See bug 335879
-        *tzp = nsnull;
-        return NS_OK;
-        // We should return an error, but don't:
-        //return NS_ERROR_INVALID_ARG;
-    }
-
-    if (tzp) {
-        icalcomponent *zonecomp = tz->GetIcalComponent();
-        *tzp = icalcomponent_get_timezone(zonecomp, nsPromiseFlatCString(tzid).get());
-    }
-
-    return NS_OK;
-}
-
 /*
  * nsIXPCScriptable impl
  */
 
 /* readonly attribute string className; */
 NS_IMETHODIMP
-calDateTime::GetClassName(char * *aClassName)
+calDateTime::GetClassName(char ** aClassName)
 {
     NS_ENSURE_ARG_POINTER(aClassName);
-    *aClassName = static_cast<char *>(nsMemory::Clone("calDateTime", 12));
-    if (!*aClassName)
-        return NS_ERROR_OUT_OF_MEMORY;
+    *aClassName = static_cast<char *>(nsMemory::Clone(CAL_STRLEN_ARGS("calDateTime") +1));
+    CAL_ENSURE_MEMORY(*aClassName);
     return NS_OK;
 }
 
 /* readonly attribute PRUint32 scriptableFlags; */
 NS_IMETHODIMP
-calDateTime::GetScriptableFlags(PRUint32 *aScriptableFlags)
+calDateTime::GetScriptableFlags(PRUint32 * aScriptableFlags)
 {
     NS_ENSURE_ARG_POINTER(aScriptableFlags);
     *aScriptableFlags = nsIXPCScriptable::WANT_GETPROPERTY |
@@ -783,7 +619,6 @@ calDateTime::GetScriptableFlags(PRUint32 *aScriptableFlags)
     return NS_OK;
 }
 
-inline 
 /* PRBool getProperty (in nsIXPConnectWrappedNative wrapper, in JSContextPtr cx, in JSObjectPtr obj, in JSVal id, in JSValPtr vp); */
 NS_IMETHODIMP
 calDateTime::GetProperty(nsIXPConnectWrappedNative *wrapper, JSContext * cx,
@@ -805,7 +640,8 @@ calDateTime::GetProperty(nsIXPConnectWrappedNative *wrapper, JSContext * cx,
             LL_L2D(msec, tmp);
 
             JSObject *obj;
-            if (mTimezone.EqualsLiteral("floating"))
+            PRBool b;
+            if (NS_SUCCEEDED(mTimezone->GetIsFloating(&b)) && b)
                 obj = js_NewDateObject(cx, mYear, mMonth, mDay, mHour, mMinute, mSecond);
             else
                 obj = js_NewDateObjectMsec(cx, msec);
@@ -953,8 +789,7 @@ calDateTime::Convert(nsIXPConnectWrappedNative *wrapper, JSContext * cx,
 
 /* void finalize (in nsIXPConnectWrappedNative wrapper, in JSContextPtr cx, in JSObjectPtr obj); */
 NS_IMETHODIMP
-calDateTime::Finalize(nsIXPConnectWrappedNative *wrapper, JSContext * cx,
-                      JSObject * obj)
+calDateTime::Finalize(nsIXPConnectWrappedNative *wrapper, JSContext * cx, JSObject * obj)
 {
     return NS_ERROR_NOT_IMPLEMENTED;
 }
@@ -999,8 +834,7 @@ calDateTime::Mark(nsIXPConnectWrappedNative *wrapper, JSContext * cx,
 #else
 /* void trace (in nsIXPConnectWrappedNative wrapper, in JSTracePtr trc, in JSObjectPtr obj); */
 NS_IMETHODIMP
-calDateTime::Trace(nsIXPConnectWrappedNative *wrapper, JSTracer *trc,
-                   JSObject *obj)
+calDateTime::Trace(nsIXPConnectWrappedNative *wrapper, JSTracer *trc, JSObject *obj)
 #endif
 {
     return NS_ERROR_NOT_IMPLEMENTED;
@@ -1029,25 +863,3 @@ calDateTime::InnerObject(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
 {
     return NS_ERROR_NOT_IMPLEMENTED;
 }
-
-/**
- * We are subclassing nsCString for mTimezone so we can check the tzid of all
- * calIDateTimes as they go by.
- */
-void calTzId::Assign(char const* c)
-{
-    this->Assign(nsDependentCString(c));
-}
-
-void calTzId::Assign(nsACString const& aStr)
-{
-    nsCString _retVal;
-    nsCOMPtr<calIICSService> const icsSvc(do_GetService(kCalICSService));
-    icsSvc->LatestTzId(aStr, _retVal);
-
-    if (_retVal.Length() != 0) {
-        nsCString::Assign(_retVal);
-    } else {
-        nsCString::Assign(aStr);
-    }
-}
diff --git a/calendar/base/src/calDateTime.h b/calendar/base/src/calDateTime.h
index 58c3c407d23..d6c34f3714e 100644
--- a/calendar/base/src/calDateTime.h
+++ b/calendar/base/src/calDateTime.h
@@ -1,4 +1,3 @@
-/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
@@ -21,6 +20,7 @@
  *
  * Contributor(s):
  *   Vladimir Vukicevic <vladimir.vukicevic@oracle.com>
+ *   Daniel Boelzle <daniel.boelzle@sun.com>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either the GNU General Public License Version 2 or later (the "GPL"), or
@@ -35,52 +35,34 @@
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
-
-#ifndef CALDATETIME_H_
-#define CALDATETIME_H_
+#if !defined(INCLUDED_CALDATETIME_H)
+#define INCLUDED_CALDATETIME_H
 
 #include "jsapi.h"
 #include "nsIXPCScriptable.h"
 #include "calIDateTime.h"
+#include "calITimezoneProvider.h"
 #include "calUtils.h"
 
 struct icaltimetype;
 typedef struct _icaltimezone icaltimezone;
 
-/* This class subclasses nsCString so we can check tzids for "freshness". */
-class calTzId : public nsCString
-{
-public:
-    /* Used by AssignLiteral when we set the tzid to "utc" or "floating". */
-    void Assign(char const* c);
-    /* Used by mTimezone.Assign as our hook to check the tzid's "freshness". */
-    void Assign(nsACString const& aStr);
-};
-
 class calDateTime : public calIDateTime,
-                    public nsIXPCScriptable
+                    public nsIXPCScriptable,
+                    public cal::XpcomBase
 {
 public:
-    calDateTime ();
-    explicit calDateTime (struct icaltimetype const* timeptr);
-    calDateTime (const calDateTime& cdt);
+    calDateTime();
+    calDateTime(icaltimetype const* icalt, calITimezone * tz);
 
-    // nsISupports interface
     NS_DECL_ISUPPORTS
-
-    // calIDateTime interface
     NS_DECL_CALIDATETIME
-
-    // nsIXPCScriptable interface
     NS_DECL_NSIXPCSCRIPTABLE
+
 protected:
-    calDateTime const& operator=(calDateTime const&);
-
     PRBool mImmutable;
-
     PRBool mIsValid;
-
-    PRTime mNativeTime;
+    PRBool mIsDate;
 
     PRInt16 mYear;
     PRInt16 mMonth;
@@ -88,21 +70,18 @@ protected:
     PRInt16 mHour;
     PRInt16 mMinute;
     PRInt16 mSecond;
-
-    PRBool mIsDate;
-    calTzId mTimezone;
-
     PRInt16 mWeekday;
     PRInt16 mYearday;
 
-    void normalize();
-    void FromIcalTime(icaltimetype const* icalt);
+    PRTime mNativeTime;
+    nsCOMPtr<calITimezone> mTimezone;
 
-    static nsresult GetIcalTZ(nsACString const& tzid, icaltimezone const** tzp);
+    void Normalize();
+    void FromIcalTime(icaltimetype const* icalt, calITimezone *tz);
 
     static PRTime IcaltimeToPRTime(icaltimetype const* icalt, icaltimezone const* tz);
     static void PRTimeToIcaltime(PRTime time, PRBool isdate,
                                  icaltimezone const* tz, icaltimetype *icalt);
 };
 
-#endif /* CALDATETIME_H_ */
+#endif // INCLUDED_CALDATETIME_H
diff --git a/calendar/base/src/calDateTimeFormatter.js b/calendar/base/src/calDateTimeFormatter.js
index f88e0d24c4a..bbf7aa5f1bf 100644
--- a/calendar/base/src/calDateTimeFormatter.js
+++ b/calendar/base/src/calDateTimeFormatter.js
@@ -60,7 +60,7 @@ function calDateTimeFormatter() {
     var probeDate = 
         Components.classes["@mozilla.org/calendar/datetime;1"]
                   .createInstance(Components.interfaces.calIDateTime);
-    probeDate.timezone = "UTC";
+    probeDate.timezone = UTC();
     probeDate.year = 2002;
     probeDate.month = 3;
     probeDate.day = 5;
diff --git a/calendar/base/src/calICSService.cpp b/calendar/base/src/calICSService.cpp
index 02148c4be3a..f249cb68f68 100644
--- a/calendar/base/src/calICSService.cpp
+++ b/calendar/base/src/calICSService.cpp
@@ -1,4 +1,3 @@
-/* -*- Mode: C++; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
@@ -22,6 +21,7 @@
  * Contributor(s):
  *   Mike Shaver <shaver@off.net>
  *   Michiel van Leeuwen <mvl@exedo.nl>
+ *   Daniel Boelzle <daniel.boelzle@sun.com>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either the GNU General Public License Version 2 or later (the "GPL"), or
@@ -36,40 +36,36 @@
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
-
-#include "calICSService.h"
-#include "calDateTime.h"
-#include "calDuration.h"
-#include "nsInterfaceHashtable.h"
-#include "nsComponentManagerUtils.h"
-#include "nsServiceManagerUtils.h"
 #include "nsStringStream.h"
-
 #ifndef MOZILLA_1_8_BRANCH
 #include "nsIClassInfoImpl.h"
 #endif
-
-#include "calIEvent.h"
-#include "calBaseCID.h"
+#include "calICSService.h"
+#include "calTimezoneService.h"
+#include "calDateTime.h"
+#include "calDuration.h"
 #include "calIErrors.h"
 
-#include "calUtils.h"
-
-static NS_DEFINE_CID(kCalICSService, CAL_ICSSERVICE_CID);
-
 extern "C" {
-#    include "ical.h"
+#include "ical.h"
+}
+
+calIcalProperty::~calIcalProperty()
+{
+    if (!mParent) {
+        icalproperty_free(mProperty);
+    }
 }
 
 NS_IMPL_ISUPPORTS1(calIcalProperty, calIIcalProperty)
 
-icalproperty*
+NS_IMETHODIMP_(icalproperty *)
 calIcalProperty::GetIcalProperty()
 {
     return mProperty;
 }
 
-icalcomponent*
+NS_IMETHODIMP_(icalcomponent *)
 calIcalProperty::GetIcalComponent()
 {
     return mParent->GetIcalComponent();
@@ -90,6 +86,12 @@ calIcalProperty::GetIcalString(nsACString &str)
     return NS_OK;
 }
 
+NS_IMETHODIMP
+calIcalProperty::ToString(nsACString& aResult)
+{
+    return GetIcalString(aResult);
+}
+
 NS_IMETHODIMP
 calIcalProperty::GetValue(nsACString &str)
 {
@@ -349,193 +351,147 @@ calIcalProperty::ClearXParameters()
     return NS_OK;
 }
 
-class calIcalComponent : public calIIcalComponent
+
+NS_IMETHODIMP
+calIcalProperty::GetValueAsDatetime(calIDateTime **dtp)
 {
-public:
-    calIcalComponent(icalcomponent *ical, calIIcalComponent *parent) : 
-        mComponent(ical), mParent(parent)
-    {
-        mTimezones.Init();
+    NS_ENSURE_ARG_POINTER(dtp);
+    return getDatetime_(toIcalComponent(mParent), mProperty, dtp);
+}
+
+nsresult calIcalProperty::getDatetime_(calIcalComponent * parent,
+                                       icalproperty * prop,
+                                       calIDateTime ** dtp)
+{
+    icalvalue * const val = icalproperty_get_value(prop);
+    icalvalue_kind const valkind = icalvalue_isa(val);
+    if (valkind != ICAL_DATETIME_VALUE && valkind != ICAL_DATE_VALUE) {
+        return NS_ERROR_UNEXPECTED;
     }
+    icaltimetype itt = icalvalue_get_datetime(val);
 
-    virtual ~calIcalComponent()
-    {
-        if (!mParent)
-            icalcomponent_free(mComponent);
-    }
-
-    NS_DECL_ISUPPORTS
-    NS_DECL_CALIICALCOMPONENT
-protected:
-    
-    nsresult GetDateTimeAttribute(icalproperty_kind kind, calIDateTime ** dtp);
-    nsresult SetDateTimeAttribute(icalproperty_kind kind, calIDateTime * dt);
-    
-    nsresult SetPropertyValue(icalproperty_kind kind, icalvalue *val);
-    nsresult SetProperty(icalproperty_kind kind, icalproperty *prop);
-
-    nsresult GetStringProperty(icalproperty_kind kind, nsACString &str)
-    {
-        icalproperty *prop =
-            icalcomponent_get_first_property(mComponent, kind);
-        if (!prop) {
-            str.Truncate();
-            str.SetIsVoid(PR_TRUE);
+    char const* tzid_ = nsnull;
+    if (!itt.is_utc) {
+        if (itt.zone) {
+            tzid_ = icaltimezone_get_tzid(const_cast<icaltimezone *>(itt.zone));
         } else {
-            str.Assign(icalvalue_get_string(icalproperty_get_value(prop)));
+            // Need to get the tzid param. Unfortunatly, libical tends to return raw
+            // ics strings, with quotes and everything. That's not what we want. Need
+            // to work around.
+            icalparameter * const tzparam = icalproperty_get_first_parameter(prop, ICAL_TZID_PARAMETER);
+            if (tzparam) {
+                tzid_ = icalparameter_get_xvalue(tzparam);
+            }
         }
-        return NS_OK;
     }
 
-    nsresult SetStringProperty(icalproperty_kind kind, const nsACString &str)
-    {
-        icalvalue *val = nsnull;
-        if (!str.IsVoid()) {
-            val = icalvalue_new_string(PromiseFlatCString(str).get());
-            if (!val)
-                return NS_ERROR_OUT_OF_MEMORY;
+    nsCOMPtr<calITimezone> tz;
+    if (tzid_) {
+        nsDependentCString const tzid(tzid_);
+        calIcalComponent * comp = nsnull;
+        if (parent) {
+            comp = parent->getParentVCalendarOrThis();
+        }
+        // look up parent if timezone is already referenced:
+        if (comp) {
+            comp->mReferencedTimezones.Get(tzid, getter_AddRefs(tz));
+        }
+        if (!tz) {
+            icaltimezone const* zone = itt.zone;
+            if (!zone && comp) {
+                // look up parent VCALENDAR for VTIMEZONE:
+                zone = icalcomponent_get_timezone(comp->mComponent, tzid_);
+                NS_ASSERTION(zone, tzid_);
+            }
+            if (zone) {
+                nsCOMPtr<calIIcalComponent> const tzComp(
+                    new calIcalComponent(icaltimezone_get_component(const_cast<icaltimezone *>(zone)),
+                                         comp));
+                CAL_ENSURE_MEMORY(tzComp);
+                tz = new calTimezone(tzComp, tzid);
+                CAL_ENSURE_MEMORY(tz);
+            }
+            if (!tz && parent) {
+                // look up tz provider:
+                calITimezoneProvider * const tzProvider = parent->getTzProvider();
+                if (tzProvider) {
+                    tzProvider->GetTimezone(tzid, getter_AddRefs(tz));
+                    NS_ASSERTION(tz, tzid_);
+                }
+            }
+            if (!tz) {
+                // look up tz in tz service.
+                // this hides errors from incorrect ics files, which could state
+                // a TZID that is not present in the ics file.
+                // The other way round, it makes this product more error tolerant.
+                cal::getTimezoneService()->GetTimezone(tzid, getter_AddRefs(tz));
+                NS_ASSERTION(tz, tzid_);
+            }
+            if (comp && tz) {
+                // assure timezone is known:
+                comp->AddTimezoneReference(tz);
+            }
+        }
+        if (tz) {
+            // correct itt which would else appear floating:
+            itt.zone = cal::getIcalTimezone(tz);
+            itt.is_utc = 0;
         }
-        return SetPropertyValue(kind, val);
-    }
-
-    nsresult GetIntProperty(icalproperty_kind kind, PRInt32 *valp)
-    {
-        icalproperty *prop =
-            icalcomponent_get_first_property(mComponent, kind);
-        if (!prop)
-            *valp = calIIcalComponent::INVALID_VALUE;
-        else
-            *valp = (PRInt32)icalvalue_get_integer(icalproperty_get_value(prop));
-        return NS_OK;
-    }
-
-    nsresult SetIntProperty(icalproperty_kind kind, PRInt32 i)
-    {
-        icalvalue *val = icalvalue_new_integer(i);
-        if (!val)
-            return NS_ERROR_OUT_OF_MEMORY;
-        return SetPropertyValue(kind, val);
-    }
-
-    void ClearAllProperties(icalproperty_kind kind);
-
-    nsresult Serialize(char **icalstr);
-    icalcomponent *mComponent;
-    nsCOMPtr<calIIcalComponent> mParent;
-    nsInterfaceHashtable<nsCStringHashKey, calIIcalComponent> mTimezones;
-};
-
-static nsresult unwrapVTimeZoneComponent(
-    calIIcalComponent *tzcal, nsCOMPtr<calIIcalComponent> & rtz)
-{
-    NS_ENSURE_ARG_POINTER(tzcal);
-    
-    nsresult rv;
-
-    // verify that we're dealing with a VTIMEZONE in a VCALENDAR
-    nsCAutoString s;
-    nsCOMPtr<calIIcalComponent> comp;
-
-    rv = tzcal->GetComponentType(s);
-    if (NS_FAILED(rv) || !s.EqualsLiteral("VCALENDAR")) {
-        NS_WARNING("unwrapVTimeZoneComponent() - "
-                   "component given is not a VCALENDAR");
-        return NS_ERROR_FAILURE;
-    }
-    rv = tzcal->GetFirstSubcomponent(NS_LITERAL_CSTRING("VTIMEZONE"),
-                                     getter_AddRefs(rtz));
-    if (NS_FAILED(rv) || !rtz) {
-        NS_WARNING("unwrapVTimeZoneComponent - "
-                   "no VTIMEZONE subcomponent");
-        return NS_ERROR_FAILURE;
     }
+    *dtp = new calDateTime(&itt, tz);
+    CAL_ENSURE_MEMORY(*dtp);
+    NS_ADDREF(*dtp);
     return NS_OK;
 }
 
-static nsresult unwrapVTimeZoneComponentWithId(
-    calIIcalComponent *tzcal,
-    nsACString & rtzid, nsCOMPtr<calIIcalComponent> & rtz)
+
+calIcalComponent::~calIcalComponent()
 {
-    nsresult rv = unwrapVTimeZoneComponent(tzcal, rtz);
-    if (NS_FAILED(rv))
-        return rv;
-    // fetch the tzid
-    nsCOMPtr<calIIcalProperty> tzidProp;
-    rv = rtz->GetFirstProperty(NS_LITERAL_CSTRING("TZID"),
-                               getter_AddRefs(tzidProp));
-    if (NS_FAILED(rv) || !tzidProp) {
-        NS_WARNING("unwrapVTimeZoneComponentWithId - failed to get TZID");
-        return NS_ERROR_FAILURE;
-    }    
-    return tzidProp->GetValue(rtzid);
+    if (!mParent) {
+        icalcomponent_free(mComponent);
+    }
 }
 
 NS_IMETHODIMP
-calIcalComponent::AddTimezoneReference(calIIcalComponent *aTimezone)
+calIcalComponent::AddTimezoneReference(calITimezone *aTimezone)
 {
+    NS_ENSURE_ARG_POINTER(aTimezone);
     nsCAutoString tzid;
-    nsCOMPtr<calIIcalComponent> tz;
-    nsresult rv = unwrapVTimeZoneComponentWithId(aTimezone, tzid, tz);
-    if (NS_FAILED(rv))
-        return rv;
-    
-    // figure out if we already have this tzid 
-    if (mTimezones.Get(tzid, nsnull))
-        return NS_OK;
-
-    if (!mTimezones.Put(tzid, aTimezone))
+    nsresult rv = aTimezone->GetTzid(tzid);
+    NS_ENSURE_SUCCESS(rv, rv);
+    if (!mReferencedTimezones.Put(tzid, aTimezone))
         return NS_ERROR_OUT_OF_MEMORY;
-
     return NS_OK;
 }
 
-NS_IMETHODIMP
-calIcalComponent::AddTimezoneReferenceById(nsACString const* tzid)
-{
-    NS_ENSURE_ARG_POINTER(tzid);
-    nsCOMPtr<calIICSService> const icsService(do_GetService(kCalICSService));
-    if (!icsService)
-        return NS_ERROR_NOT_AVAILABLE;
-    nsCOMPtr<calIIcalComponent> tz;
-    icsService->GetTimezone(*tzid, getter_AddRefs(tz));
-    if (!tz) {
-        // Uh, we didn't find this timezone. This should somehow be bad.
-        NS_WARNING("Timezone was not found in database!");
-        return NS_ERROR_NOT_AVAILABLE;
-    }
-    return AddTimezoneReference(tz);
-}
-
 PR_STATIC_CALLBACK(PLDHashOperator)
-TimezoneHashToTimezoneArray(const nsACString& aTzid,
-                            calIIcalComponent *aComponent,
-                            void *aArg)
+TimezoneHashToTimezoneArray(nsACString const& tzid, calITimezone * tz, void * arg)
 {
-    calIIcalComponent ***arrayPtr = static_cast<calIIcalComponent ***>(aArg);
-    NS_ADDREF(**arrayPtr = aComponent);
-    (*arrayPtr)++;
+    calITimezone *** const arrayPtr = static_cast<calITimezone ***>(arg);
+    NS_ADDREF(**arrayPtr = tz);
+    ++(*arrayPtr);
     return PL_DHASH_NEXT;
 }
 
 NS_IMETHODIMP
-calIcalComponent::GetReferencedTimezones(PRUint32 *aCount,
-                                         calIIcalComponent ***aTimezones)
+calIcalComponent::GetReferencedTimezones(PRUint32 * aCount, calITimezone *** aTimezones)
 {
-    PRUint32 count = mTimezones.Count();
+    NS_ENSURE_ARG_POINTER(aCount);
+    NS_ENSURE_ARG_POINTER(aTimezones);
 
+    PRUint32 const count = mReferencedTimezones.Count();
     if (count == 0) {
         *aCount = 0;
         *aTimezones = nsnull;
         return NS_OK;
     }
 
-    calIIcalComponent **timezones = (calIIcalComponent **) nsMemory::Alloc(sizeof(calIIcalComponent*) * count);
-    if (!timezones)
-        return NS_ERROR_OUT_OF_MEMORY;
-
+    calITimezone ** const timezones = static_cast<calITimezone **>(
+        nsMemory::Alloc(sizeof(calITimezone *) * count));
+    CAL_ENSURE_MEMORY(timezones);
     // tzptr will get used as an iterator by the enumerator function
-    calIIcalComponent **tzptr = timezones;
-    mTimezones.EnumerateRead(TimezoneHashToTimezoneArray, (void *) &tzptr);
+    calITimezone ** tzptr = timezones;
+    mReferencedTimezones.EnumerateRead(TimezoneHashToTimezoneArray, &tzptr);
 
     *aTimezones = timezones;
     *aCount = count;
@@ -696,8 +652,50 @@ calIcalComponent::Set##Attrname(PRInt32 val)                    \
     return SetProperty(ICAL_##ICALNAME##_PROPERTY, prop);       \
 }                                                               \
 
-nsresult calIcalComponent::GetDateTimeAttribute(
-    icalproperty_kind kind, calIDateTime ** dtp)
+nsresult calIcalComponent::GetStringProperty(icalproperty_kind kind, nsACString &str)
+{
+    icalproperty *prop = icalcomponent_get_first_property(mComponent, kind);
+    if (!prop) {
+        str.Truncate();
+        str.SetIsVoid(PR_TRUE);
+    } else {
+        str.Assign(icalvalue_get_string(icalproperty_get_value(prop)));
+    }
+    return NS_OK;
+}
+
+nsresult calIcalComponent::SetStringProperty(icalproperty_kind kind,
+                                             const nsACString &str)
+{
+    icalvalue *val = nsnull;
+    if (!str.IsVoid()) {
+        val = icalvalue_new_string(PromiseFlatCString(str).get());
+        if (!val)
+            return NS_ERROR_OUT_OF_MEMORY;
+    }
+    return SetPropertyValue(kind, val);
+}
+
+nsresult calIcalComponent::GetIntProperty(icalproperty_kind kind, PRInt32 *valp)
+{
+    icalproperty *prop = icalcomponent_get_first_property(mComponent, kind);
+    if (!prop)
+        *valp = calIIcalComponent::INVALID_VALUE;
+    else
+        *valp = (PRInt32)icalvalue_get_integer(icalproperty_get_value(prop));
+    return NS_OK;
+}
+
+nsresult calIcalComponent::SetIntProperty(icalproperty_kind kind, PRInt32 i)
+{
+    icalvalue *val = icalvalue_new_integer(i);
+    if (!val)
+        return NS_ERROR_OUT_OF_MEMORY;
+    return SetPropertyValue(kind, val);
+}
+
+nsresult calIcalComponent::GetDateTimeAttribute(icalproperty_kind kind,
+                                                calIDateTime ** dtp)
 {
     NS_ENSURE_ARG_POINTER(dtp);
     icalproperty *prop = icalcomponent_get_first_property(mComponent, kind);
@@ -708,108 +706,8 @@ nsresult calIcalComponent::GetDateTimeAttribute(
     return calIcalProperty::getDatetime_(this, prop, dtp);
 }
 
-NS_IMETHODIMP
-calIcalProperty::GetValueAsDatetime(calIDateTime **dtp)
-{
-    NS_ENSURE_ARG_POINTER(dtp);
-    return getDatetime_(mParent, mProperty, dtp);
-}
-
-nsresult calIcalProperty::getDatetime_(calIIcalComponent *comp,
-                                       icalproperty *prop,
-                                       calIDateTime **dtp)
-{
-    struct icaltimetype itt =
-        icalvalue_get_datetime(icalproperty_get_value(prop));
-
-    // Need to get the tzid param. Unfortunatly, libical tends to return raw
-    // ics strings, with quotes and everything. That's not what we want. Need
-    // to work around.
-    icalparameter* tzparam = icalproperty_get_first_parameter(prop, ICAL_TZID_PARAMETER);
-    const char *tzid = nsnull;
-    if (tzparam)
-        tzid = icalparameter_get_xvalue(tzparam);
-
-    if (tzid) {
-        // look up tz in ics service, which btw caches commonly used tzones.
-        // this hides errors from incorrect ics files, which could state
-        // a TZID that is not present in the ics file.
-        // The other way round, it makes this product more error tolerant.
-        nsCOMPtr<calIICSService> const icsService(do_GetService(kCalICSService));
-        if (!icsService)
-            return NS_ERROR_NOT_AVAILABLE;
-        nsCOMPtr<calIIcalComponent> tzcal;
-        nsresult rv = icsService->GetTimezone(nsDependentCString(tzid),
-                                              getter_AddRefs(tzcal));
-        if (NS_FAILED(rv) || !tzcal) {
-            /* Now, see, libical sucks.
-               We have to walk up to our parent VCALENDAR and try to find
-               this tzid */
-            icalcomponent *vcalendar = nsnull;
-            if (comp)
-                vcalendar = comp->GetIcalComponent();
-            while (vcalendar && icalcomponent_isa(vcalendar) !=
-                   ICAL_VCALENDAR_COMPONENT)
-                vcalendar = icalcomponent_get_parent(vcalendar);
-            if (!vcalendar) {
-                NS_WARNING("VCALENDAR not found while looking for VTIMEZONE!");
-                return NS_ERROR_FAILURE;
-            }
-            icaltimezone *zone = icalcomponent_get_timezone(vcalendar, tzid);
-            if (!zone) {
-                NS_WARNING("Can't find specified VTIMEZONE in VCALENDAR!");
-                return calIErrors::INVALID_TIMEZONE;
-            }
-            icalcomponent * tzcomp = icaltimezone_get_component(zone);
-            if (tzcomp == nsnull) {
-                NS_WARNING("Can't get VTIMEZONE!");
-                return NS_ERROR_FAILURE;
-            }
-            
-            // create new VCALENDAR out of VTIMEZONE and publish to ics service.
-            // calDateTime works on ics service's timezones.
-            rv = icsService->CreateIcalComponent(nsDependentCString("VCALENDAR"),
-                                                 getter_AddRefs(tzcal));
-            if (NS_FAILED(rv))
-                return rv;
-            // VTIMEZONE:
-            tzcomp = icalcomponent_new_clone(tzcomp);
-            nsCOMPtr<calIIcalComponent> const subComp(
-                new calIcalComponent(tzcomp, nsnull) );
-            if (!subComp) {
-                icalcomponent_free(tzcomp);
-                return NS_ERROR_OUT_OF_MEMORY;
-            }
-            rv = tzcal->AddSubcomponent(subComp);
-            if (NS_FAILED(rv))
-                return rv;
-            
-            // publish to ics service:
-            nsCOMPtr<calIIcalComponent> const tzcal_(tzcal);
-            rv = icsService->AddTimezone(
-                tzcal_, // unknown latitude, longitude:
-                nsDependentCString(""), nsDependentCString(""),
-                getter_AddRefs(tzcal));
-            if (NS_FAILED(rv))
-                return rv;
-        }
-        if (comp) {
-            // assure timezone is referenced in component:
-            comp->AddTimezoneReference(tzcal);
-        }
-        // correct itt which would else appear floating:
-        itt.zone = icalcomponent_get_timezone(tzcal->GetIcalComponent(), tzid);
-        itt.is_utc = 0;
-    }
-    calDateTime * const dt = new calDateTime(&itt);
-    if (!dt)
-        return NS_ERROR_OUT_OF_MEMORY;
-    NS_ADDREF(*dtp = dt);
-    return NS_OK;
-}
-
-nsresult calIcalComponent::SetDateTimeAttribute(
-    icalproperty_kind kind, calIDateTime * dt)
+nsresult calIcalComponent::SetDateTimeAttribute(icalproperty_kind kind,
+                                                calIDateTime * dt)
 {
     ClearAllProperties(kind);
     PRBool isValid, wantTz = PR_FALSE;
@@ -817,8 +715,7 @@ nsresult calIcalComponent::SetDateTimeAttribute(
         return NS_OK;
     }
     icalproperty *prop = icalproperty_new(kind);
-    if (!prop)
-        return NS_ERROR_OUT_OF_MEMORY;
+    CAL_ENSURE_MEMORY(prop);
     nsresult rc = calIcalProperty::setDatetime_(this, prop, dt);
     if (NS_SUCCEEDED(rc))
         icalcomponent_add_property(mComponent, prop);
@@ -831,41 +728,35 @@ NS_IMETHODIMP
 calIcalProperty::SetValueAsDatetime(calIDateTime *dt)
 {
     NS_ENSURE_ARG_POINTER(dt);
-    return setDatetime_(mParent, mProperty, dt);
+    return setDatetime_(toIcalComponent(mParent), mProperty, dt);
 }
 
-nsresult calIcalProperty::setDatetime_(calIIcalComponent *comp,
-                                       icalproperty *prop,
-                                       calIDateTime *dt)
+nsresult calIcalProperty::setDatetime_(calIcalComponent * parent,
+                                       icalproperty * prop,
+                                       calIDateTime * dt)
 {
-    struct icaltimetype itt;
+    NS_ENSURE_ARG_POINTER(prop);
+    NS_ENSURE_ARG_POINTER(dt);
+
+    icaltimetype itt;
     dt->ToIcalTime(&itt);
-
-    PRBool wantTz = PR_FALSE;
-    nsCAutoString tzid;
-    if (NS_SUCCEEDED(dt->GetTimezone(tzid)) &&
-        !tzid.IsEmpty() && !tzid.EqualsLiteral("UTC") &&
-        !tzid.EqualsLiteral("floating"))
-    {
-        wantTz = PR_TRUE;
-        if (comp) {
-            nsresult rc = comp->AddTimezoneReferenceById(&tzid);
-            if (NS_FAILED(rc))
-                return rc;
-        }
-        // else set TZID even though no containing component
-        // is present to add the VTIMEZONE to
-    }
-
-    icalvalue *val = icalvalue_new_datetime(itt);
-    if (!val)
-        return NS_ERROR_OUT_OF_MEMORY;
+    icalvalue * const val = icalvalue_new_datetime(itt);
+    CAL_ENSURE_MEMORY(val);
     icalproperty_set_value(prop, val);
-    if (wantTz) {
-        icalproperty_set_parameter_from_string(
-            prop, "TZID", nsPromiseFlatCString(tzid).get());
+
+    if (!itt.is_utc && itt.zone) {
+        if (parent) {
+            nsCOMPtr<calITimezone> tz;
+            nsresult rv = dt->GetTimezone(getter_AddRefs(tz));
+            NS_ENSURE_SUCCESS(rv, rv);
+            rv = parent->getParentVCalendarOrThis()->AddTimezoneReference(tz);
+            NS_ENSURE_SUCCESS(rv, rv);
+        } // else set TZID even though no containing component
+          // is present to add the VTIMEZONE to
+        icalparameter * const param = icalparameter_new_from_value_string(
+            ICAL_TZID_PARAMETER, icaltimezone_get_tzid(const_cast<icaltimezone *>(itt.zone)));
+        icalproperty_set_parameter(prop, param);
     }
-    
     return NS_OK;
 }
 
@@ -892,32 +783,49 @@ calIcalComponent::Get##Attrname(calIDuration **dtp)                     \
     icalproperty *prop =                                                \
         icalcomponent_get_first_property(mComponent,                    \
                                          ICAL_##ICALNAME##_PROPERTY);   \
-    calDuration *dt;                                                    \
     if (!prop) {                                                        \
         *dtp = nsnull;  /* invalid duration */                          \
         return NS_OK;                                                   \
     }                                                                   \
     struct icaldurationtype idt =                                       \
         icalvalue_get_duration(icalproperty_get_value(prop));           \
-    dt = new calDuration(&idt);                                         \
-    if (!dt)                                                            \
-        return NS_ERROR_OUT_OF_MEMORY;                                  \
-    NS_ADDREF(*dtp = dt);                                               \
+    *dtp = new calDuration(&idt);                                       \
+    CAL_ENSURE_MEMORY(*dtp);                                            \
+    NS_ADDREF(*dtp);                                                    \
     return NS_OK;                                                       \
 }
 
 NS_IMPL_ISUPPORTS1(calIcalComponent, calIIcalComponent)
 
-icalcomponent*
+NS_IMETHODIMP_(icalcomponent *)
 calIcalComponent::GetIcalComponent()
 {
     return mComponent;
 }
 
+NS_IMETHODIMP_(icaltimezone *)
+calIcalComponent::GetIcalTimezone()
+{
+    // xxx todo: weak assumption that this VTIMEZONE still has a parent since
+    //           we need it to get an icaltimezone...
+    NS_ASSERTION(mParent, "VTIMEZONE has no parent!");
+    if (!mTimezone && mParent && icalcomponent_isa(mComponent) == ICAL_VTIMEZONE_COMPONENT) {
+        icalproperty * const tzidProp = icalcomponent_get_first_property(mComponent, ICAL_TZID_PROPERTY);
+        NS_ASSERTION(tzidProp, "no TZID property in VTIMEZONE!?");
+        if (tzidProp) {
+            mTimezone = icalcomponent_get_timezone(mParent->GetIcalComponent(),
+                                                   icalvalue_get_string(icalproperty_get_value(tzidProp)));
+        }
+    }
+    return mTimezone;
+}
+
 NS_IMETHODIMP
 calIcalComponent::GetFirstSubcomponent(const nsACString& kind,
                                        calIIcalComponent **subcomp)
 {
+    NS_ENSURE_ARG_POINTER(subcomp);
+
     icalcomponent_kind compkind =
         icalcomponent_string_to_kind(PromiseFlatCString(kind).get());
 
@@ -933,8 +841,7 @@ calIcalComponent::GetFirstSubcomponent(const nsACString& kind,
     }
 
     *subcomp = new calIcalComponent(ical, this);
-    if (!*subcomp)
-        return NS_ERROR_OUT_OF_MEMORY;
+    CAL_ENSURE_MEMORY(*subcomp);
     NS_ADDREF(*subcomp);
     return NS_OK;
 }
@@ -943,6 +850,8 @@ NS_IMETHODIMP
 calIcalComponent::GetNextSubcomponent(const nsACString& kind,
                                       calIIcalComponent **subcomp)
 {
+    NS_ENSURE_ARG_POINTER(subcomp);
+
     icalcomponent_kind compkind =
         icalcomponent_string_to_kind(PromiseFlatCString(kind).get());
 
@@ -958,8 +867,7 @@ calIcalComponent::GetNextSubcomponent(const nsACString& kind,
     }
 
     *subcomp = new calIcalComponent(ical, this);
-    if (!*subcomp)
-        return NS_ERROR_OUT_OF_MEMORY;
+    CAL_ENSURE_MEMORY(*subcomp);
     NS_ADDREF(*subcomp);
     return NS_OK;
 }
@@ -985,9 +893,9 @@ COMP_STRING_ATTRIBUTE(Categories, CATEGORIES, categories)
 COMP_STRING_ATTRIBUTE(URL, URL, url)
 COMP_INT_ATTRIBUTE(Priority, PRIORITY, priority)
 COMP_STRING_TO_GENERAL_ENUM_ATTRIBUTE(IcalClass, CLASS, class)
+RO_COMP_DURATION_ATTRIBUTE(Duration, DURATION)
 COMP_DATE_ATTRIBUTE(StartTime, DTSTART)
 COMP_DATE_ATTRIBUTE(EndTime, DTEND)
-RO_COMP_DURATION_ATTRIBUTE(Duration, DURATION)
 COMP_DATE_ATTRIBUTE(DueTime, DUE)
 COMP_DATE_ATTRIBUTE(StampTime, DTSTAMP)
 COMP_DATE_ATTRIBUTE(LastModified, LASTMODIFIED)
@@ -995,14 +903,11 @@ COMP_DATE_ATTRIBUTE(CreatedTime, CREATED)
 COMP_DATE_ATTRIBUTE(CompletedTime, COMPLETED)
 COMP_DATE_ATTRIBUTE(RecurrenceId, RECURRENCEID)
 
-void
-calIcalComponent::ClearAllProperties(icalproperty_kind kind)
+void calIcalComponent::ClearAllProperties(icalproperty_kind kind)
 {
-    for (icalproperty *prop =
-             icalcomponent_get_first_property(mComponent, kind),
-             *next;
-         prop;
-         prop = next) {
+    for (icalproperty *prop = icalcomponent_get_first_property(mComponent, kind), *next;
+         prop; prop = next)
+    {
         next = icalcomponent_get_next_property(mComponent, kind);
         icalcomponent_remove_property(mComponent, prop);
         icalproperty_free(prop);
@@ -1010,13 +915,14 @@ calIcalComponent::ClearAllProperties(icalproperty_kind kind)
 }
 
 PR_STATIC_CALLBACK(PLDHashOperator)
-AddTimezoneComponentToIcal(const nsACString& aTzid,
-                           calIIcalComponent *aTimezone,
-                           void *aArg)
+AddTimezoneComponentToIcal(nsACString const& tzid, calITimezone * tz, void * arg)
 {
-    icalcomponent *comp = static_cast<icalcomponent *>(aArg);
-    icalcomponent *tzcomp = icalcomponent_new_clone(aTimezone->GetIcalComponent());
-    icalcomponent_merge_component(comp, tzcomp);
+    icalcomponent * const comp = static_cast<icalcomponent *>(arg);
+    icaltimezone * icaltz = cal::getIcalTimezone(tz);
+    if (icaltz) {
+        icalcomponent * const tzcomp = icalcomponent_new_clone(icaltimezone_get_component(icaltz));
+        icalcomponent_add_component(comp, tzcomp);
+    }
     return PL_DHASH_NEXT;
 }
 
@@ -1034,15 +940,20 @@ calIcalComponent::SerializeToICS(nsACString &serialized)
     return NS_OK;
 }
 
+NS_IMETHODIMP
+calIcalComponent::ToString(nsACString& aResult)
+{
+    return SerializeToICS(aResult);
+}
+
 NS_IMETHODIMP
 calIcalComponent::SerializeToICSStream(nsIInputStream **aStreamResult)
 {
-    char *icalstr;
+    NS_ENSURE_ARG_POINTER(aStreamResult);
 
+    char *icalstr;
     nsresult rv = Serialize(&icalstr);
-    if (NS_FAILED(rv)) {
-        return rv;
-    }
+    NS_ENSURE_SUCCESS(rv, rv);
 
     nsCOMPtr<nsIStringInputStream> const aStringStream(
         do_CreateInstance(NS_STRINGINPUTSTREAM_CONTRACTID, &rv));
@@ -1059,15 +970,16 @@ calIcalComponent::SerializeToICSStream(nsIInputStream **aStreamResult)
 nsresult
 calIcalComponent::Serialize(char **icalstr)
 {
+    NS_ENSURE_ARG_POINTER(icalstr);
+
     // add the timezone bits
-    if (icalcomponent_isa(mComponent) == ICAL_VCALENDAR_COMPONENT &&
-        mTimezones.Count() > 0)
-    {
-        mTimezones.EnumerateRead(AddTimezoneComponentToIcal, mComponent);
+    if (icalcomponent_isa(mComponent) == ICAL_VCALENDAR_COMPONENT && mReferencedTimezones.Count() > 0) {
+        mReferencedTimezones.EnumerateRead(AddTimezoneComponentToIcal, mComponent);
     }
 
     *icalstr = icalcomponent_as_ical_string(mComponent);
     if (!*icalstr) {
+        // xxx todo: what about NS_ERROR_OUT_OF_MEMORY?
 #ifdef DEBUG
         fprintf(stderr, "Error serializing: %d (%s)\n",
                 icalerrno, icalerror_strerror(icalerrno));
@@ -1083,10 +995,11 @@ calIcalComponent::Serialize(char **icalstr)
 NS_IMETHODIMP
 calIcalComponent::Clone(calIIcalComponent **_retval)
 {
+    NS_ENSURE_ARG_POINTER(_retval);
     icalcomponent * cloned = icalcomponent_new_clone(mComponent);
     if (cloned == nsnull)
         return NS_ERROR_OUT_OF_MEMORY;
-    calIcalComponent *comp = new calIcalComponent(cloned, nsnull);
+    calIcalComponent * const comp = new calIcalComponent(cloned, nsnull, getTzProvider());
     if (comp == nsnull) {
         icalcomponent_free(cloned);
         return NS_ERROR_OUT_OF_MEMORY;
@@ -1098,6 +1011,8 @@ calIcalComponent::Clone(calIIcalComponent **_retval)
 NS_IMETHODIMP
 calIcalComponent::AddSubcomponent(calIIcalComponent *comp)
 {
+    NS_ENSURE_ARG_POINTER(comp);
+
     /* XXX mildly unsafe assumption here.
      * To fix it, I will:
      * - check the object's classinfo to find out if I have one of my
@@ -1107,22 +1022,18 @@ calIcalComponent::AddSubcomponent(calIIcalComponent *comp)
      * I should probably also return the new/reused component so that the
      * caller has something it can poke at all live-like.
      */
-    calIcalComponent *ical = static_cast<calIcalComponent *>(comp);
-    if(ical->mParent)
-        ical->mComponent = icalcomponent_new_clone(ical->mComponent);
+    calIcalComponent * const ical = toIcalComponent(comp);
 
     PRUint32 tzCount = 0;
-    calIIcalComponent **timezones = nsnull;;
-    nsresult rv;
-
-    rv = ical->GetReferencedTimezones(&tzCount, &timezones);
-    if (NS_FAILED(rv))
-        return rv;
+    calITimezone ** timezones = nsnull;
+    nsresult rv = ical->GetReferencedTimezones(&tzCount, &timezones);
+    NS_ENSURE_SUCCESS(rv, rv);
 
+    calIcalComponent * const vcal = getParentVCalendarOrThis();
     PRBool failed = PR_FALSE;
     for (PRUint32 i = 0; i < tzCount; i++) {
         if (!failed) {
-            rv = this->AddTimezoneReference(timezones[i]);
+            rv = vcal->AddTimezoneReference(timezones[i]);
             if (NS_FAILED(rv))
                 failed = PR_TRUE;
         }
@@ -1135,24 +1046,30 @@ calIcalComponent::AddSubcomponent(calIIcalComponent *comp)
     if (failed)
         return rv;
 
-    icalcomponent_add_component(mComponent, ical->mComponent);
+    if (ical->mParent) {
+        ical->mComponent = icalcomponent_new_clone(ical->mComponent);
+    }
     ical->mParent = this;
+    icalcomponent_add_component(mComponent, ical->mComponent);
     return NS_OK;
 }
 
-NS_IMETHODIMP
-calIcalComponent::RemoveSubcomponent(calIIcalComponent *comp)
-{
-    calIcalComponent *ical = static_cast<calIcalComponent *>(comp);
-    icalcomponent_remove_component(mComponent, ical->mComponent);
-    ical->mParent = nsnull;
-    return NS_OK;
-}
+// NS_IMETHODIMP
+// IcalComponent::RemoveSubcomponent(calIIcalComponent *comp)
+// {
+//     NS_ENSURE_ARG_POINTER(comp);
+//     calIcalComponent *ical = static_cast<calIcalComponent *>(comp);
+//     icalcomponent_remove_component(mComponent, ical->mComponent);
+//     ical->mParent = nsnull;
+//     return NS_OK;
+// }
 
 NS_IMETHODIMP
 calIcalComponent::GetFirstProperty(const nsACString &kind,
                                    calIIcalProperty **prop)
 {
+    NS_ENSURE_ARG_POINTER(prop);
+
     icalproperty_kind propkind =
         icalproperty_string_to_kind(PromiseFlatCString(kind).get());
 
@@ -1180,16 +1097,16 @@ calIcalComponent::GetFirstProperty(const nsACString &kind,
     }
 
     *prop = new calIcalProperty(icalprop, this);
-    if (!*prop)
-        return NS_ERROR_OUT_OF_MEMORY;
+    CAL_ENSURE_MEMORY(*prop);
     NS_ADDREF(*prop);
     return NS_OK;
 }
 
 NS_IMETHODIMP
-calIcalComponent::GetNextProperty(const nsACString &kind,
-                                  calIIcalProperty **prop)
+calIcalComponent::GetNextProperty(const nsACString &kind, calIIcalProperty **prop)
 {
+    NS_ENSURE_ARG_POINTER(prop);
+
     icalproperty_kind propkind =
         icalproperty_string_to_kind(PromiseFlatCString(kind).get());
 
@@ -1216,60 +1133,62 @@ calIcalComponent::GetNextProperty(const nsACString &kind,
     }
 
     *prop = new calIcalProperty(icalprop, this);
-    if (!*prop)
-        return NS_ERROR_OUT_OF_MEMORY;
+    CAL_ENSURE_MEMORY(*prop);
     NS_ADDREF(*prop);
     return NS_OK;
 }
 
 NS_IMETHODIMP
-calIcalComponent::AddProperty(calIIcalProperty *prop)
+calIcalComponent::AddProperty(calIIcalProperty * prop)
 {
-    // XXX like AddSubcomponent, this is questionable
     NS_ENSURE_ARG_POINTER(prop);
-
-    calIcalProperty *ical = static_cast<calIcalProperty *>(prop);
-    if(ical->mParent)
+    // We assume a calIcalProperty is passed in (else the cast wouldn't run and
+    // we are about to crash), so we assume that this ICS service code has created
+    // the property.
+    calIcalProperty * const ical = toIcalProperty(prop);
+    if (ical->mParent) {
         ical->mProperty = icalproperty_new_clone(ical->mProperty);
-    icalcomponent_add_property(mComponent, ical->mProperty);
+    }
     ical->mParent = this;
+    icalcomponent_add_property(mComponent, ical->mProperty);
 
-    // make sure timezone definition will be included:
-    icalparameter * const tzparam = icalproperty_get_first_parameter(
-        ical->mProperty, ICAL_TZID_PARAMETER);
-    if (tzparam) {
-        char const* const tzid = icalparameter_get_xvalue(tzparam);
-        if (tzid) {
-            // should adding the property fail in case the timezone isn't present?
-            nsDependentCString const tzid_(tzid);
-            AddTimezoneReferenceById(&tzid_);
+    nsCOMPtr<calIDateTime> dt;
+    if (NS_SUCCEEDED(prop->GetValueAsDatetime(getter_AddRefs(dt))) && dt) {
+        // make sure timezone definition will be included:
+        nsCOMPtr<calITimezone> tz;
+        if (NS_SUCCEEDED(dt->GetTimezone(getter_AddRefs(tz))) && tz) {
+            getParentVCalendarOrThis()->AddTimezoneReference(tz);
         }
     }
-
     return NS_OK;
 }
 
-NS_IMETHODIMP
-calIcalComponent::RemoveProperty(calIIcalProperty *prop)
-{
-    // XXX like AddSubcomponent, this is questionable
-    calIcalProperty *ical = static_cast<calIcalProperty *>(prop);
-    icalcomponent_remove_property(mComponent, ical->mProperty);
-    ical->mParent = nsnull;
-    return NS_OK;
-}
+// If you add then remove a property/component, the referenced
+// timezones won't get purged out. There's currently no client code.
+
+// NS_IMETHODIMP
+// calIcalComponent::RemoveProperty(calIIcalProperty *prop)
+// {
+//     NS_ENSURE_ARG_POINTER(prop);
+//     // XXX like AddSubcomponent, this is questionable
+//     calIcalProperty *ical = static_cast<calIcalProperty *>(prop);
+//     icalcomponent_remove_property(mComponent, ical->mProperty);
+//     ical->mParent = nsnull;
+//     return NS_OK;
+// }
 
 NS_IMPL_ISUPPORTS1_CI(calICSService, calIICSService)
 
 calICSService::calICSService()
 {
-    mTzHash.Init();
 }
 
 NS_IMETHODIMP
 calICSService::ParseICS(const nsACString& serialized,
+                        calITimezoneProvider *tzProvider,
                         calIIcalComponent **component)
 {
+    NS_ENSURE_ARG_POINTER(component);
     icalcomponent *ical =
         icalparser_parse_string(PromiseFlatCString(serialized).get());
     if (!ical) {
@@ -1282,7 +1201,7 @@ calICSService::ParseICS(const nsACString& serialized,
         // so no need for a conversion table or anything.
         return calIErrors::ICS_ERROR_BASE + icalerrno;
     }
-    calIcalComponent *comp = new calIcalComponent(ical, nsnull);
+    calIcalComponent *comp = new calIcalComponent(ical, nsnull, tzProvider);
     if (!comp) {
         icalcomponent_free(ical);
         return NS_ERROR_OUT_OF_MEMORY;
@@ -1292,9 +1211,9 @@ calICSService::ParseICS(const nsACString& serialized,
 }
 
 NS_IMETHODIMP
-calICSService::CreateIcalComponent(const nsACString &kind,
-                                   calIIcalComponent **comp)
+calICSService::CreateIcalComponent(const nsACString &kind, calIIcalComponent **comp)
 {
+    NS_ENSURE_ARG_POINTER(comp);
     icalcomponent_kind compkind = 
         icalcomponent_string_to_kind(PromiseFlatCString(kind).get());
 
@@ -1317,9 +1236,9 @@ calICSService::CreateIcalComponent(const nsACString &kind,
 }
 
 NS_IMETHODIMP
-calICSService::CreateIcalProperty(const nsACString &kind,
-                                  calIIcalProperty **prop)
+calICSService::CreateIcalProperty(const nsACString &kind, calIIcalProperty **prop)
 {
+    NS_ENSURE_ARG_POINTER(prop);
     icalproperty_kind propkind = 
         icalproperty_string_to_kind(PromiseFlatCString(kind).get());
 
@@ -1334,224 +1253,7 @@ calICSService::CreateIcalProperty(const nsACString &kind,
         icalproperty_set_x_name(icalprop, PromiseFlatCString(kind).get());
 
     *prop = new calIcalProperty(icalprop, nsnull);
-    if (!*prop)
-        return NS_ERROR_OUT_OF_MEMORY;
+    CAL_ENSURE_MEMORY(*prop);
     NS_ADDREF(*prop);
     return NS_OK;
 }
-
-/**
- ** Timezone bits
- **/
-
-// include tzdata, to get ical_timezone_data_struct
-#include "tzdata.c"
-
-/* XXX We should really be using the global defined in tzdata.c for this. */
-#define MOZCAL_TZID_PREFIX "/mozilla.org/20070129_1/"
-
-#define STRLEN_ARGS(x) x, sizeof(x) - 1
-
-TimezoneEntry const* calICSService::getTimezoneEntry(nsACString const& tzid)
-{
-    TimezoneEntry * pEntry = nsnull;
-    PRBool const bFound = mTzHash.Get(tzid, &pEntry);
-    if ((!bFound || pEntry == nsnull) &&
-        StringBeginsWith(tzid,
-                         nsDependentCString(STRLEN_ARGS(MOZCAL_TZID_PREFIX)))) {
-        // not found, look up in static tab:
-        for (PRUint32 i = 0; ical_timezone_data[i].tzid != nsnull; ++i) {
-            if (tzid.Equals(ical_timezone_data[i].tzid)) {
-                ical_timezone_data_struct const& tzdata = ical_timezone_data[i];
-                nsCOMPtr<calIIcalComponent> icalComp;
-                if (NS_FAILED(
-                        ParseICS(nsDependentCString(tzdata.icstimezone),
-                                 getter_AddRefs(icalComp) )))
-                    return 0;
-                
-                nsAutoPtr<TimezoneEntry> entry(
-                    new TimezoneEntry(nsDependentCString(tzdata.latitude),
-                                      nsDependentCString(tzdata.longitude),
-                                      icalComp) );
-                if (!mTzHash.Put(tzid, entry.get()))
-                    return 0;
-                pEntry = entry.forget();
-                break;
-            }
-        }
-    }
-    return pEntry;
-}
-
-NS_IMETHODIMP calICSService::AddTimezone(
-    calIIcalComponent * tzCal, const nsACString & tzLatitude,
-    const nsACString & tzLongitude, calIIcalComponent **_retval)
-{
-    NS_ENSURE_ARG_POINTER(_retval);
-    
-    nsCAutoString tzid;
-    nsCOMPtr<calIIcalComponent> tz;
-    nsresult rv = unwrapVTimeZoneComponentWithId(tzCal, tzid, tz);
-    if (NS_FAILED(rv))
-        return rv;
-    
-    TimezoneEntry const* pEntry = getTimezoneEntry(tzid);
-    if (pEntry == nsnull) {
-        nsAutoPtr<TimezoneEntry> entry(
-            new TimezoneEntry(tzLatitude, tzLongitude, tzCal) );
-        if (!mTzHash.Put(tzid, entry.get()))
-            return NS_ERROR_OUT_OF_MEMORY;
-        pEntry = entry.forget();
-    }
-    NS_ADDREF(*_retval = pEntry->mTzCal);
-    return NS_OK;
-}
-
-NS_IMETHODIMP
-calICSService::GetTimezone(const nsACString& tzid,
-                           calIIcalComponent **_retval)
-{
-    NS_ENSURE_ARG_POINTER(_retval);
-    TimezoneEntry const* pEntry = getTimezoneEntry(tzid);
-    if (pEntry == nsnull)
-        return calIErrors::INVALID_TIMEZONE;
-    NS_ADDREF(*_retval = pEntry->mTzCal);
-    return NS_OK;
-}
-
-PR_STATIC_CALLBACK(PLDHashOperator) TimezoneEntryHashToTimezoneIdArray(
-    const nsACString& aTzid, TimezoneEntry * pEntry, void * aArg)
-{
-    nsCStringArray * pArray = static_cast<nsCStringArray *>(aArg);
-    // ignore static ones, those are added nevertheless:
-    if (!StringBeginsWith(
-            aTzid, nsDependentCString(STRLEN_ARGS(MOZCAL_TZID_PREFIX))))
-        pArray->AppendCString(aTzid);
-    return PL_DHASH_NEXT;
-}
-
-NS_IMETHODIMP
-calICSService::GetTimezoneIds(nsIUTF8StringEnumerator **aTzids)
-{
-    NS_ENSURE_ARG_POINTER(aTzids);
-    PRUint32 const arlen =
-        sizeof(ical_timezone_data) / sizeof(ical_timezone_data[0]);
-    nsAutoPtr<nsCStringArray> pArray(
-        new nsCStringArray(mTzHash.Count() + arlen));
-    if (pArray == nsnull)
-        return NS_ERROR_OUT_OF_MEMORY;
-    // add added ones:
-    mTzHash.EnumerateRead(TimezoneEntryHashToTimezoneIdArray, pArray);
-    // add static ones:
-    for (PRUint32 i = 0; ical_timezone_data[i].tzid != nsnull; ++i) {
-        pArray->AppendCString(nsDependentCString(ical_timezone_data[i].tzid));
-    }
-    pArray->Sort();
-    return cal::createUTF8StringEnumerator(pArray, aTzids);
-}
-
-NS_IMETHODIMP
-calICSService::GetTimezoneLatitude(const nsACString& tzid, nsACString& _retval)
-{
-    TimezoneEntry const* pEntry = getTimezoneEntry(tzid);
-    if (pEntry == nsnull)
-        return NS_ERROR_FAILURE;
-    _retval = pEntry->mLatitude;
-    return NS_OK;
-}
-
-NS_IMETHODIMP
-calICSService::GetTimezoneLongitude(const nsACString& tzid, nsACString& _retval)
-{
-    TimezoneEntry const* pEntry = getTimezoneEntry(tzid);
-    if (pEntry == nsnull)
-        return NS_ERROR_FAILURE;
-    _retval = pEntry->mLongitude;
-    return NS_OK;
-}
-
-NS_IMETHODIMP
-calICSService::GetTzIdPrefix(nsACString& _retval)
-{
-    _retval.Assign(kTzIdPrefix);
-
-    return NS_OK;
-}
-
-/**
- * LatestTzId
- * Gets updated timezone ID (tzId) for a given tzId.
- * - If this isn't a mozilla.org tzId:
- *      return nothing
- * - If the tzId name was changed or the tzId was deleted:
- *      return updated tzId
- * - If the tzId's dtstamp is different from our current dtstamp:
- *      return updated tzId
- * - Otherwise, don't change the tzId and return nothing.
- */
-NS_IMETHODIMP
-calICSService::LatestTzId(const nsACString& tzid, nsACString& _retval) {
-    // Ensure _retval is both initialized and empty.
-    _retval.Truncate();
-
-    // If it doesn't start with "/mozilla.org/" then it isn't ours.
-    if (!StringBeginsWith(
-            tzid, nsDependentCString(STRLEN_ARGS("/mozilla.org/")))) {
-        return NS_OK;
-    }
-
-    // We know that our tzids look like "/mozilla.org/<dtstamp>/continent/..."
-    // The ending of the mozilla prefix is the index of that slash before the
-    // continent. Therefore, we start looking for the prefix-ending slash
-    // after position 13.
-    PRInt32 prefixEnd = tzid.FindChar('/', 13);
-    PRInt32 continentEnd = tzid.FindChar('/', prefixEnd + 1);
-
-    // Go through our list of deletions and changes in Olsen, and update
-    // these to entirely new zones.
-    nsCAutoString continent(Substring(tzid, prefixEnd + 1,
-                                      continentEnd - (prefixEnd + 1)));
-
-    // XXX We want to make this table-driven at some point in the future.
-
-    if (continent.EqualsLiteral("Africa")) {
-        if (tzid.EqualsLiteral("/mozilla.org/20050126_1/Africa/Asmera")) {
-            _retval.AssignLiteral("/mozilla.org/20070129_1/Africa/Asmara");
-        } else if (tzid.EqualsLiteral("/mozilla.org/20050126_1/Africa/Timbuktu")) {
-            _retval.AssignLiteral("/mozilla.org/20070129_1/Africa/Bamako");
-        }
-    } else if (continent.EqualsLiteral("Atlantic")) {
-        if (tzid.EqualsLiteral("/mozilla.org/20050126_1/Atlantic/Faeroe")) {
-            _retval.AssignLiteral("/mozilla.org/20070129_1/Atlantic/Faroe");
-        }
-    } else if (continent.EqualsLiteral("America")) {
-        if (tzid.EqualsLiteral("/mozilla.org/20050126_1/America/Argentina/ComodRivadavia")) {
-            _retval.AssignLiteral("/mozilla.org/20070129_1/America/Argentina/Catamarca");
-        } else if (tzid.EqualsLiteral("/mozilla.org/20050126_1/America/Louisville")) {
-            _retval.AssignLiteral("/mozilla.org/20070129_1/America/Kentucky/Louisville");
-        }
-    } else if (continent.EqualsLiteral("Europe")) {
-        if (tzid.EqualsLiteral("/mozilla.org/20050126_1/Europe/Belfast")) {
-            _retval.AssignLiteral("/mozilla.org/20070129_1/Europe/London");
-        }
-    } else if (continent.EqualsLiteral("Pacific")) {
-        if (tzid.EqualsLiteral("/mozilla.org/20050126_1/Pacific/Yap")) {
-            _retval.AssignLiteral("/mozilla.org/20070129_1/Pacific/Truk");
-        }
-    }
-
-    // If the zone's locale was not changed and the zone was not
-    // deleted (i.e. we haven't already created _retVal, then
-    // we just need to update the timestamp.
-    const nsCAutoString tzIdPrefix(kTzIdPrefix);
-    if ((_retval.Length() == 0) &&
-        (tzIdPrefix != Substring(tzid, 0, prefixEnd + 1))) {
-        // TODO: This assumes that new zones will always be later. If we are
-        // ever going to support mixing our TZID headers, then this needs to
-        // be a date comparison.
-        _retval = tzIdPrefix;
-        _retval += Substring(tzid, prefixEnd + 1,
-                             tzid.Length() - (prefixEnd + 1));
-    }
-    return NS_OK;
-}
diff --git a/calendar/base/src/calICSService.h b/calendar/base/src/calICSService.h
index 08bcce459c1..297c34277f6 100644
--- a/calendar/base/src/calICSService.h
+++ b/calendar/base/src/calICSService.h
@@ -1,4 +1,3 @@
-/* -*- Mode: C++; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
@@ -21,6 +20,7 @@
  *
  * Contributor(s):
  *   Mike Shaver <mike.x.shaver@oracle.com>
+ *   Daniel Boelzle <daniel.boelzle@sun.com>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either the GNU General Public License Version 2 or later (the "GPL"), or
@@ -35,69 +35,128 @@
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
+#if !defined(INCLUDED_CALICSSERVICE_H)
+#define INCLUDED_CALICSSERVICE_H
 
 #include "nsCOMPtr.h"
 #include "calIICSService.h"
-
-#include "nsClassHashtable.h"
+#include "calITimezoneProvider.h"
+#include "nsInterfaceHashtable.h"
+#include "calUtils.h"
 
 extern "C" {
-#   include "ical.h"
+#include "ical.h"
 }
 
-class calIIcalComponent;
-class calIcalComponent;
-
-struct TimezoneEntry
-{
-    nsCString const mLatitude;
-    nsCString const mLongitude;
-    nsCOMPtr<calIIcalComponent> const mTzCal;
-    
-    TimezoneEntry(nsACString const& latitude,
-                  nsACString const& longitude,
-                  nsCOMPtr<calIIcalComponent> const& tzCal)
-        : mLatitude(latitude), mLongitude(longitude), mTzCal(tzCal) {}
-};
-
-class calICSService : public calIICSService
+class calICSService : public calIICSService,
+                      public cal::XpcomBase
 {
 public:
     calICSService();
-    virtual ~calICSService() { }
-    
+
     NS_DECL_ISUPPORTS
     NS_DECL_CALIICSSERVICE
-protected:
-    nsClassHashtable<nsCStringHashKey, TimezoneEntry> mTzHash;
-    TimezoneEntry const* getTimezoneEntry(nsACString const& tzid);
 };
 
-class calIcalProperty : public calIIcalProperty
+class calIcalComponent;
+
+class calIcalProperty : public calIIcalProperty,
+                        public cal::XpcomBase
 {
+    friend class calIcalComponent;
 public:
-    calIcalProperty(icalproperty *prop, calIIcalComponent *parent) :
-        mProperty(prop), mParent(parent) { }
-    virtual ~calIcalProperty()
-    {
-        if (!mParent)
-            icalproperty_free(mProperty);
-    }
-
-    icalproperty * getIcalProperty() const { return mProperty; }
-
-    static nsresult getDatetime_(calIIcalComponent *comp,
-                                 icalproperty *prop,
-                                 calIDateTime **dtp);
-    static nsresult setDatetime_(calIIcalComponent *comp,
-                                 icalproperty *prop,
-                                 calIDateTime *dt);
+    calIcalProperty(icalproperty * prop, calIIcalComponent * parent)
+        : mProperty(prop), mParent(parent) {}
 
     NS_DECL_ISUPPORTS
     NS_DECL_CALIICALPROPERTY
 
-    friend class calIcalComponent;
 protected:
-    icalproperty *mProperty;
+    virtual ~calIcalProperty();
+
+    static nsresult getDatetime_(calIcalComponent *parent,
+                                 icalproperty *prop,
+                                 calIDateTime **dtp);
+    static nsresult setDatetime_(calIcalComponent *parent,
+                                 icalproperty *prop,
+                                 calIDateTime *dt);
+
+    icalproperty *              mProperty;
     nsCOMPtr<calIIcalComponent> mParent;
 };
+
+class calIcalComponent : public calIIcalComponent,
+                         public cal::XpcomBase
+{
+    friend class calIcalProperty;
+public:
+    calIcalComponent(icalcomponent *ical, calIIcalComponent *parent,
+                     calITimezoneProvider *tzProvider = nsnull)
+        : mComponent(ical), mParent(parent), mTimezone(nsnull), mTzProvider(tzProvider)
+    {
+        mReferencedTimezones.Init();
+    }
+
+    NS_DECL_ISUPPORTS
+    NS_DECL_CALIICALCOMPONENT
+
+protected:
+    virtual ~calIcalComponent();
+
+    calITimezoneProvider * getTzProvider() const {
+        // walk up the parents to find a tz provider:
+        calIcalComponent const * that = this;
+        while (that) {
+            calITimezoneProvider * const ret = that->mTzProvider;
+            if (ret) {
+                return ret;
+            }
+            calIIcalComponent * const p = that->mParent;
+            that = static_cast<calIcalComponent const *>(p);
+        }
+        return nsnull;
+    }
+
+    calIcalComponent * getParentVCalendarOrThis() {
+        // walk up the parents to find a VCALENDAR:
+        calIcalComponent * that = this;
+        while (that && icalcomponent_isa(that->mComponent) != ICAL_VCALENDAR_COMPONENT) {
+            calIIcalComponent * const p = that->mParent;
+            that = static_cast<calIcalComponent *>(p);
+        }
+        if (!that)
+            that = this;
+        return that;
+    }
+
+    nsresult GetDateTimeAttribute(icalproperty_kind kind, calIDateTime ** dtp);
+    nsresult SetDateTimeAttribute(icalproperty_kind kind, calIDateTime * dt);
+
+    nsresult SetPropertyValue(icalproperty_kind kind, icalvalue *val);
+    nsresult SetProperty(icalproperty_kind kind, icalproperty *prop);
+
+    nsresult GetStringProperty(icalproperty_kind kind, nsACString &str);
+    nsresult SetStringProperty(icalproperty_kind kind, const nsACString &str);
+
+    nsresult GetIntProperty(icalproperty_kind kind, PRInt32 *valp);
+    nsresult SetIntProperty(icalproperty_kind kind, PRInt32 i);
+
+    void ClearAllProperties(icalproperty_kind kind);
+
+    nsresult Serialize(char ** icalstr);
+
+    nsInterfaceHashtable<nsCStringHashKey, calITimezone> mReferencedTimezones;
+    icalcomponent *                                      mComponent;
+    icaltimezone *                                       mTimezone; // set iff VTIMEZONE
+    nsCOMPtr<calIIcalComponent>                          mParent;
+    nsCOMPtr<calITimezoneProvider> const                 mTzProvider;
+};
+
+inline calIcalProperty * toIcalProperty(calIIcalProperty * p) {
+    return static_cast<calIcalProperty *>(p);
+}
+inline calIcalComponent * toIcalComponent(calIIcalComponent * p) {
+    return static_cast<calIcalComponent *>(p);
+}
+
+#endif // INCLUDED_CALICSSERVICE_H
diff --git a/calendar/base/src/calIcsParser.js b/calendar/base/src/calIcsParser.js
index 53cf9673ac8..150439e165e 100644
--- a/calendar/base/src/calIcsParser.js
+++ b/calendar/base/src/calIcsParser.js
@@ -53,11 +53,11 @@ function QueryInterface(aIID) {
 };
 
 calIcsParser.prototype.parseString =
-function ip_parseString(aICSString) {
+function ip_parseString(aICSString, aTzProvider) {
     icsSvc = Components.classes["@mozilla.org/calendar/ics-service;1"]
                        .getService(Components.interfaces.calIICSService);
 
-    var rootComp = icsSvc.parseICS(aICSString);
+    var rootComp = icsSvc.parseICS(aICSString, aTzProvider);
     var calComp;
     // libical returns the vcalendar component if there is just one vcalendar.
     // If there are multiple vcalendars, it returns an xroot component, with
@@ -95,14 +95,12 @@ function ip_parseString(aICSString) {
             var item = null;
             switch (subComp.componentType) {
             case "VEVENT":
-                var event = Components.classes["@mozilla.org/calendar/event;1"]
-                                      .createInstance(Components.interfaces.calIEvent);
-                item = event;
+                item = Components.classes["@mozilla.org/calendar/event;1"]
+                                 .createInstance(Components.interfaces.calIEvent);
                 break;
             case "VTODO":
-                var todo = Components.classes["@mozilla.org/calendar/todo;1"]
-                                     .createInstance(Components.interfaces.calITodo);
-                item = todo;
+                item = Components.classes["@mozilla.org/calendar/todo;1"]
+                                 .createInstance(Components.interfaces.calITodo);
                 break;
             case "VTIMEZONE":
                 // this should already be attached to the relevant
@@ -155,7 +153,7 @@ function ip_parseString(aICSString) {
 };
 
 calIcsParser.prototype.parseFromStream =
-function ip_parseFromStream(aStream) {
+function ip_parseFromStream(aStream, aTzProvider) {
     // Read in the string. Note that it isn't a real string at this point, 
     // because likely, the file is utf8. The multibyte chars show up as multiple
     // 'chars' in this string. So call it an array of octets for now.
@@ -186,7 +184,7 @@ function ip_parseFromStream(aStream) {
     // ICS files are always UTF8
     unicodeConverter.charset = "UTF-8";
     var str = unicodeConverter.convertFromByteArray(octetArray, octetArray.length);
-    return this.parseString(str);
+    return this.parseString(str, aTzProvider);
 }
 
 calIcsParser.prototype.getItems =
diff --git a/calendar/base/src/calItemBase.js b/calendar/base/src/calItemBase.js
index d4940ff2a22..cb9402b3cc5 100644
--- a/calendar/base/src/calItemBase.js
+++ b/calendar/base/src/calItemBase.js
@@ -74,7 +74,7 @@ calItemBase.prototype = {
             var cal = this.calendar;
             // some unused delim character:
             this.mHashId = [encodeURIComponent(this.id),
-                            rid ? rid.getInTimezone("UTC").icalString : "",
+                            rid ? rid.getInTimezone(UTC()).icalString : "",
                             cal ? encodeURIComponent(cal.id) : ""].join("#");
         }
         return this.mHashId;
@@ -808,7 +808,7 @@ function icalFromString(str)
 {
     const icssvc = Components.classes["@mozilla.org/calendar/ics-service;1"].
         getService(Components.interfaces.calIICSService);
-    return icssvc.parseICS(str);
+    return icssvc.parseICS(str, null);
 }
 
 function icalProp(kind)
diff --git a/calendar/base/src/calItipItem.js b/calendar/base/src/calItipItem.js
index 905376deacd..61e901421df 100644
--- a/calendar/base/src/calItipItem.js
+++ b/calendar/base/src/calItipItem.js
@@ -165,7 +165,7 @@ calItipItem.prototype = {
     init: function ciiI(aIcalString) {
         var parser = Components.classes["@mozilla.org/calendar/ics-parser;1"].
                      createInstance(Components.interfaces.calIIcsParser);
-        parser.parseString(aIcalString);
+        parser.parseString(aIcalString, null);
         this.mItemList = parser.getItems({});
         this.mPropertiesList = parser.getProperties({});
 
diff --git a/calendar/base/src/calPeriod.cpp b/calendar/base/src/calPeriod.cpp
index 9ca68ae3a85..4be5a3a0476 100644
--- a/calendar/base/src/calPeriod.cpp
+++ b/calendar/base/src/calPeriod.cpp
@@ -109,8 +109,7 @@ NS_IMETHODIMP calPeriod::SetStart(calIDateTime *aValue)
         return NS_ERROR_OBJECT_IS_IMMUTABLE;
     // rfc2445 says that periods are always in utc. libical ignore that,
     // so we need the conversion here.
-    nsresult const rv = aValue->GetInTimezone(
-        NS_LITERAL_CSTRING("UTC"), getter_AddRefs(mStart));
+    nsresult const rv = aValue->GetInTimezone(cal::UTC(), getter_AddRefs(mStart));
     NS_ENSURE_SUCCESS(rv, rv);
     return mStart->MakeImmutable();
 }
@@ -127,8 +126,7 @@ NS_IMETHODIMP calPeriod::SetEnd(calIDateTime *aValue)
     NS_ENSURE_ARG_POINTER(aValue);
     if (mImmutable)
         return NS_ERROR_OBJECT_IS_IMMUTABLE;
-    nsresult const rv = aValue->GetInTimezone(
-        NS_LITERAL_CSTRING("UTC"), getter_AddRefs(mEnd));
+    nsresult const rv = aValue->GetInTimezone(cal::UTC(), getter_AddRefs(mEnd));
     NS_ENSURE_SUCCESS(rv, rv);
     return mEnd->MakeImmutable();
 }
@@ -163,9 +161,9 @@ calPeriod::ToIcalPeriod(struct icalperiodtype *icalp)
 void
 calPeriod::FromIcalPeriod(struct icalperiodtype const* icalp)
 {
-    mStart = new calDateTime(&(icalp->start));
+    mStart = new calDateTime(&(icalp->start), nsnull);
     mStart->MakeImmutable();
-    mEnd = new calDateTime(&(icalp->end));
+    mEnd = new calDateTime(&(icalp->end), nsnull);
     mEnd->MakeImmutable();
     return;
 }
@@ -196,7 +194,7 @@ calPeriod::SetIcalString(const nsACString& aIcalString)
     ip = icalperiodtype_from_string(nsPromiseFlatCString(aIcalString).get());
     //XXX Shortcut. Assumes nobody tried to overrule our impl. of calIDateTime
     //    Should use NS_NEWXPCOM()
-    mStart = new calDateTime(&ip.start);
-    mEnd = new calDateTime(&ip.end);
+    mStart = new calDateTime(&ip.start, nsnull);
+    mEnd = new calDateTime(&ip.end, nsnull);
     return NS_OK;
 }
diff --git a/calendar/base/src/calRecurrenceInfo.js b/calendar/base/src/calRecurrenceInfo.js
index 26967eeb761..6c68ab0cf4c 100644
--- a/calendar/base/src/calRecurrenceInfo.js
+++ b/calendar/base/src/calRecurrenceInfo.js
@@ -720,8 +720,8 @@ calRecurrenceInfo.prototype = {
         }
     
         // convert both dates to UTC since subtractDate is not timezone aware.
-        aOldStartTime = aOldStartTime.getInTimezone("UTC");
-        aNewStartTime = aNewStartTime.getInTimezone("UTC");
+        aOldStartTime = aOldStartTime.getInTimezone(UTC());
+        aNewStartTime = aNewStartTime.getInTimezone(UTC());
         var timeDiff = aNewStartTime.subtractDate(aOldStartTime);
         var exceptions = this.getExceptionIds({});
         var modifiedExceptions = [];
diff --git a/calendar/base/src/calRecurrenceRule.cpp b/calendar/base/src/calRecurrenceRule.cpp
index ba9277b6428..73217d1dcb1 100644
--- a/calendar/base/src/calRecurrenceRule.cpp
+++ b/calendar/base/src/calRecurrenceRule.cpp
@@ -1,4 +1,3 @@
-/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
@@ -51,10 +50,6 @@
 #include "nsIClassInfoImpl.h"
 #endif
 
-extern "C" {
-    #include "ical.h"
-}
-
 #include <climits>
 
 NS_IMPL_ISUPPORTS2_CI(calRecurrenceRule, calIRecurrenceItem, calIRecurrenceRule)
@@ -64,20 +59,13 @@ calRecurrenceRule::calRecurrenceRule()
       mIsNegative(PR_FALSE),
       mIsByCount(PR_FALSE)
 {
-    mIcalRecur = new struct icalrecurrencetype;
-    icalrecurrencetype_clear(mIcalRecur);
-}
-
-calRecurrenceRule::~calRecurrenceRule()
-{
-    delete mIcalRecur;
+    icalrecurrencetype_clear(&mIcalRecur);
 }
 
 NS_IMETHODIMP
 calRecurrenceRule::GetIsMutable(PRBool *aResult)
 {
     NS_ENSURE_ARG_POINTER(aResult);
-
     *aResult = !mImmutable;
     return NS_OK;
 }
@@ -85,9 +73,6 @@ calRecurrenceRule::GetIsMutable(PRBool *aResult)
 NS_IMETHODIMP
 calRecurrenceRule::MakeImmutable()
 {
-    if (mImmutable)
-        return NS_ERROR_FAILURE; // XXX another error code
-
     mImmutable = PR_TRUE;
     return NS_OK;
 }
@@ -95,13 +80,12 @@ calRecurrenceRule::MakeImmutable()
 NS_IMETHODIMP
 calRecurrenceRule::Clone(calIRecurrenceItem **aResult)
 {
-    calRecurrenceRule *crc = new calRecurrenceRule;
-    if (!crc)
-        return NS_ERROR_OUT_OF_MEMORY;
+    calRecurrenceRule * const crc = new calRecurrenceRule();
+    CAL_ENSURE_MEMORY(crc);
 
     crc->mIsNegative = mIsNegative;
     crc->mIsByCount = mIsByCount;
-    *(crc->mIcalRecur) = *mIcalRecur;
+    crc->mIcalRecur = mIcalRecur;
 
     NS_ADDREF(*aResult = crc);
     return NS_OK;
@@ -112,7 +96,6 @@ NS_IMETHODIMP
 calRecurrenceRule::GetIsNegative(PRBool *_retval)
 {
     NS_ENSURE_ARG_POINTER(_retval);
-
     *_retval = mIsNegative;
     return NS_OK;
 }
@@ -121,8 +104,7 @@ NS_IMETHODIMP
 calRecurrenceRule::SetIsNegative(PRBool aIsNegative)
 {
     if (mImmutable)
-        return NS_ERROR_FAILURE; // XXX CAL_ERROR_ITEM_IS_IMMUTABLE
-
+        return NS_ERROR_OBJECT_IS_IMMUTABLE;
     mIsNegative = aIsNegative;
     return NS_OK;
 }
@@ -133,8 +115,8 @@ calRecurrenceRule::GetIsFinite(PRBool *_retval)
 {
     NS_ENSURE_ARG_POINTER(_retval);
 
-    if ((mIsByCount && mIcalRecur->count == 0) ||
-        (!mIsByCount && icaltime_is_null_time(mIcalRecur->until)))
+    if ((mIsByCount && mIcalRecur.count == 0) ||
+        (!mIsByCount && icaltime_is_null_time(mIcalRecur.until)))
     {
         *_retval = PR_FALSE;
     } else {
@@ -147,7 +129,7 @@ calRecurrenceRule::GetIsFinite(PRBool *_retval)
 NS_IMETHODIMP
 calRecurrenceRule::GetType(nsACString &aType)
 {
-    switch (mIcalRecur->freq) {
+    switch (mIcalRecur.freq) {
 #define RECUR_HELPER(x) \
         case ICAL_##x##_RECURRENCE: aType.AssignLiteral( #x ); break
         RECUR_HELPER(SECONDLY);
@@ -169,7 +151,7 @@ NS_IMETHODIMP
 calRecurrenceRule::SetType(const nsACString &aType)
 {
 #define RECUR_HELPER(x) \
-    if (aType.EqualsLiteral( #x )) mIcalRecur->freq = ICAL_##x##_RECURRENCE
+    if (aType.EqualsLiteral( #x )) mIcalRecur.freq = ICAL_##x##_RECURRENCE
     RECUR_HELPER(SECONDLY);
     else RECUR_HELPER(MINUTELY);
     else RECUR_HELPER(HOURLY);
@@ -179,7 +161,7 @@ calRecurrenceRule::SetType(const nsACString &aType)
     else RECUR_HELPER(YEARLY);
 #undef RECUR_HELPER
     else if (aType.IsEmpty() || aType.EqualsLiteral(""))
-        mIcalRecur->freq = ICAL_NO_RECURRENCE;
+        mIcalRecur.freq = ICAL_NO_RECURRENCE;
     else
         return NS_ERROR_FAILURE;
 
@@ -195,10 +177,10 @@ calRecurrenceRule::GetCount(PRInt32 *aRecurCount)
     if (!mIsByCount)
         return NS_ERROR_FAILURE;
 
-    if (mIcalRecur->count == 0 && icaltime_is_null_time(mIcalRecur->until)) {
+    if (mIcalRecur.count == 0 && icaltime_is_null_time(mIcalRecur.until)) {
         *aRecurCount = -1;
-    } else if (mIcalRecur->count) {
-        *aRecurCount = mIcalRecur->count;
+    } else if (mIcalRecur.count) {
+        *aRecurCount = mIcalRecur.count;
     } else {
         // count wasn't set, so we don't know
         return NS_ERROR_FAILURE;
@@ -213,12 +195,12 @@ calRecurrenceRule::SetCount(PRInt32 aRecurCount)
     if (aRecurCount != -1) {
         if (aRecurCount < 0 || aRecurCount > INT_MAX)
             return NS_ERROR_ILLEGAL_VALUE;
-        mIcalRecur->count = static_cast<int>(aRecurCount);
+        mIcalRecur.count = static_cast<int>(aRecurCount);
     } else {
-        mIcalRecur->count = 0;
+        mIcalRecur.count = 0;
     }
 
-    mIcalRecur->until = icaltime_null_time();
+    mIcalRecur.until = icaltime_null_time();
 
     mIsByCount = PR_TRUE;
 
@@ -234,12 +216,10 @@ calRecurrenceRule::GetEndDate(calIDateTime * *aRecurEnd)
     if (mIsByCount)
         return NS_ERROR_FAILURE;
 
-    if (!icaltime_is_null_time(mIcalRecur->until)) {
-        calDateTime *cdt = new calDateTime(&mIcalRecur->until);
-        if (!cdt)
-            return NS_ERROR_OUT_OF_MEMORY;
-
-        NS_ADDREF (*aRecurEnd = cdt);
+    if (!icaltime_is_null_time(mIcalRecur.until)) {
+        *aRecurEnd = new calDateTime(&mIcalRecur.until, nsnull);
+        CAL_ENSURE_MEMORY(*aRecurEnd);
+        NS_ADDREF(*aRecurEnd);
     } else {
         // infinite recurrence
         *aRecurEnd = nsnull; 
@@ -250,16 +230,26 @@ calRecurrenceRule::GetEndDate(calIDateTime * *aRecurEnd)
 NS_IMETHODIMP
 calRecurrenceRule::SetEndDate(calIDateTime * aRecurEnd)
 {
+    NS_ENSURE_ARG_POINTER(aRecurEnd);
     if (aRecurEnd) {
+        nsCOMPtr<calIDateTime> dt(aRecurEnd);
+        nsCOMPtr<calITimezone> tz;
+        aRecurEnd->GetTimezone(getter_AddRefs(tz));
+        PRBool b;
+        if (NS_SUCCEEDED(tz->GetIsUTC(&b)) && !b &&
+            NS_SUCCEEDED(tz->GetIsFloating(&b)) && !b) {
+            // convert to UTC:
+            aRecurEnd->GetInTimezone(cal::UTC(), getter_AddRefs(dt));
+        }
         struct icaltimetype itt;
-        aRecurEnd->ToIcalTime(&itt);
+        dt->ToIcalTime(&itt);
 
-        mIcalRecur->until = itt;
+        mIcalRecur.until = itt;
     } else {
-        mIcalRecur->until = icaltime_null_time();
+        mIcalRecur.until = icaltime_null_time();
     }
 
-    mIcalRecur->count = 0;
+    mIcalRecur.count = 0;
 
     mIsByCount = PR_FALSE;
 
@@ -279,7 +269,7 @@ NS_IMETHODIMP
 calRecurrenceRule::GetInterval(PRInt32 *aInterval)
 {
     NS_ENSURE_ARG_POINTER(aInterval);
-    *aInterval = mIcalRecur->interval;
+    *aInterval = mIcalRecur.interval;
     return NS_OK;
 }
 
@@ -288,7 +278,7 @@ calRecurrenceRule::SetInterval(PRInt32 aInterval)
 {
     if (aInterval < 0 || aInterval > SHRT_MAX)
         return NS_ERROR_ILLEGAL_VALUE;
-    mIcalRecur->interval = static_cast<short>(aInterval);
+    mIcalRecur.interval = static_cast<short>(aInterval);
     return NS_OK;
 }
 
@@ -305,11 +295,11 @@ calRecurrenceRule::GetComponent(const nsACString &aComponentType, PRUint32 *aCou
     if (aComponentType.EqualsLiteral( #_comptype )) {                    \
         int count;                                                      \
         for (count = 0; count < _icalmax; count++) {                    \
-            if (mIcalRecur->_icalvar[count] == ICAL_RECURRENCE_ARRAY_MAX) \
+            if (mIcalRecur._icalvar[count] == ICAL_RECURRENCE_ARRAY_MAX) \
                 break;                                                  \
         }                                                               \
         if (count) {                                                    \
-            *aValues = (PRInt16*) nsMemory::Clone(mIcalRecur->_icalvar, \
+            *aValues = (PRInt16*) nsMemory::Clone(mIcalRecur._icalvar,  \
                                                   count * sizeof(PRInt16)); \
             if (!*aValues) return NS_ERROR_OUT_OF_MEMORY;               \
         } else {                                                        \
@@ -347,9 +337,9 @@ calRecurrenceRule::SetComponent(const nsACString& aComponentType, PRUint32 aCoun
     if (aComponentType.EqualsLiteral( #_comptype )) {                    \
         if (aCount > _icalmax)                                          \
             return NS_ERROR_FAILURE;                                    \
-        memcpy(mIcalRecur->_icalvar, aValues, aCount * sizeof(PRInt16)); \
+        memcpy(mIcalRecur._icalvar, aValues, aCount * sizeof(PRInt16)); \
         if (aCount < _icalmax)                                          \
-            mIcalRecur->_icalvar[aCount] = ICAL_RECURRENCE_ARRAY_MAX;    \
+            mIcalRecur._icalvar[aCount] = ICAL_RECURRENCE_ARRAY_MAX;    \
     }
 
     HANDLE_COMPONENT(BYSECOND, by_second, ICAL_BY_SECOND_SIZE)
@@ -387,8 +377,7 @@ calRecurrenceRule::GetNextOccurrence(calIDateTime *aStartTime,
     aOccurrenceTime->ToIcalTime(&occurtime);
 
     icalrecur_iterator* recur_iter;
-    recur_iter = icalrecur_iterator_new (*mIcalRecur,
-                                         dtstart);
+    recur_iter = icalrecur_iterator_new(mIcalRecur, dtstart);
     if (!recur_iter)
         return NS_ERROR_OUT_OF_MEMORY;
 
@@ -407,8 +396,11 @@ calRecurrenceRule::GetNextOccurrence(calIDateTime *aStartTime,
         return NS_OK;
     }
 
-    nsCOMPtr<calIDateTime> cdt = new calDateTime(&next);
-    NS_ADDREF(*_retval = cdt);
+    nsCOMPtr<calITimezone> tz;
+    aStartTime->GetTimezone(getter_AddRefs(tz));
+    *_retval = new calDateTime(&next, tz);
+    CAL_ENSURE_MEMORY(*_retval);
+    NS_ADDREF(*_retval);
     return NS_OK;
 }
 
@@ -439,18 +431,18 @@ calRecurrenceRule::GetOccurrences(calIDateTime *aStartTime,
 
     // make sure the request is sane; infinite recurrence
     // with no end time is bad times.
-    if (!aMaxCount && !aRangeEnd && mIcalRecur->count == 0 && icaltime_is_null_time(mIcalRecur->until))
+    if (!aMaxCount && !aRangeEnd && mIcalRecur.count == 0 && icaltime_is_null_time(mIcalRecur.until))
         return NS_ERROR_INVALID_ARG;
 
     nsCOMArray<calIDateTime> dates;
 
 #ifdef DEBUG_dbo
     {
-        char* ss = icalrecurrencetype_as_string(mIcalRecur);
+        char const * const ss = icalrecurrencetype_as_string(&mIcalRecur);
         nsCAutoString tst, tend;
         aRangeStart->ToString(tst);
         aRangeEnd->ToString(tend);
-        printf("RULE: [%s -> %s, %d]: %s\n", tst.get(), tend.get(), mIcalRecur->count, ss);
+        printf("RULE: [%s -> %s, %d]: %s\n", tst.get(), tend.get(), mIcalRecur.count, ss);
     }
 #endif
 
@@ -458,6 +450,9 @@ calRecurrenceRule::GetOccurrences(calIDateTime *aStartTime,
     aRangeStart->ToIcalTime(&rangestart);
     rangestart = ensureDateTime(rangestart);
     aStartTime->ToIcalTime(&dtstart);
+    nsCOMPtr<calITimezone> tz;
+    aStartTime->GetTimezone(getter_AddRefs(tz));
+
     if (aRangeEnd) {
         aRangeEnd->ToIcalTime(&dtend);
         dtend = ensureDateTime(dtend);
@@ -472,7 +467,7 @@ calRecurrenceRule::GetOccurrences(calIDateTime *aStartTime,
     }
 
     icalrecur_iterator* recur_iter;
-    recur_iter = icalrecur_iterator_new (*mIcalRecur, dtstart);
+    recur_iter = icalrecur_iterator_new(mIcalRecur, dtstart);
     if (!recur_iter)
         return NS_ERROR_OUT_OF_MEMORY;
 
@@ -492,7 +487,7 @@ calRecurrenceRule::GetOccurrences(calIDateTime *aStartTime,
         if (aRangeEnd && icaltime_compare(dtNext, dtend) >= 0)
             break;
 
-        nsCOMPtr<calIDateTime> cdt = new calDateTime(&next);
+        calIDateTime * const cdt = new calDateTime(&next, tz);
         if (!cdt) {
             icalrecur_iterator_free(recur_iter);
             return NS_ERROR_OUT_OF_MEMORY;
@@ -536,9 +531,8 @@ calRecurrenceRule::GetOccurrences(calIDateTime *aStartTime,
 NS_IMETHODIMP
 calRecurrenceRule::GetIcalProperty(calIIcalProperty **prop)
 {
-    icalproperty* rrule = icalproperty_new_rrule(*mIcalRecur);
-    if (!rrule)
-        return NS_ERROR_OUT_OF_MEMORY; // XXX map error code
+    icalproperty * const rrule = icalproperty_new_rrule(mIcalRecur);
+    CAL_ENSURE_MEMORY(rrule);
     *prop = new calIcalProperty(rrule, nsnull);
     if (!*prop) {
         icalproperty_free(rrule);
@@ -555,15 +549,10 @@ calRecurrenceRule::SetIcalProperty(calIIcalProperty *aProp)
     NS_ENSURE_ARG_POINTER(aProp);
 
     if (mImmutable)
-        return NS_ERROR_FAILURE;
+        return NS_ERROR_OBJECT_IS_IMMUTABLE;
 
-    nsresult rv;
-
-    // XXX we really should do some CID checking here
-    calIcalProperty *cprop = static_cast<calIcalProperty *>(aProp);
     nsCAutoString propname;
-
-    rv = cprop->GetPropertyName(propname);
+    nsresult rv = aProp->GetPropertyName(propname);
     NS_ENSURE_SUCCESS(rv, rv);
     if (propname.EqualsLiteral("RRULE"))
         mIsNegative = PR_FALSE;
@@ -575,7 +564,7 @@ calRecurrenceRule::SetIcalProperty(calIIcalProperty *aProp)
     icalproperty *prop;
     struct icalrecurrencetype icalrecur;
 
-    prop = cprop->getIcalProperty();
+    prop = aProp->GetIcalProperty();
 
     icalrecur = icalproperty_get_rrule(prop);
 
@@ -594,7 +583,7 @@ calRecurrenceRule::SetIcalProperty(calIIcalProperty *aProp)
     else
         mIsByCount = PR_FALSE;
 
-    *mIcalRecur = icalrecur;
+    mIcalRecur = icalrecur;
 
     return NS_OK;
 }
diff --git a/calendar/base/src/calRecurrenceRule.h b/calendar/base/src/calRecurrenceRule.h
index 82f785d9782..0b703501bce 100644
--- a/calendar/base/src/calRecurrenceRule.h
+++ b/calendar/base/src/calRecurrenceRule.h
@@ -1,4 +1,3 @@
-/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
@@ -21,6 +20,7 @@
  *
  * Contributor(s):
  *   Vladimir Vukicevic <vladimir.vukicevic@oracle.com>
+ *   Daniel Boelzle <daniel.boelzle@sun.com>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either the GNU General Public License Version 2 or later (the "GPL"), or
@@ -35,31 +35,31 @@
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
-
-#ifndef CALRECURRENCERULE_H_
-#define CALRECURRENCERULE_H_
+#if !defined(INCLUDED_CAL_RECURRENCERULE_H)
+#define INCLUDED_CAL_RECURRENCERULE_H
 
 #include "calIRecurrenceRule.h"
+#include "calUtils.h"
 
-struct icalrecurrencetype;
+extern "C" {
+#include "ical.h"
+}
 
-class calRecurrenceRule : public calIRecurrenceRule
+class calRecurrenceRule : public calIRecurrenceRule,
+                          public cal::XpcomBase
 {
 public:
     calRecurrenceRule();
-    ~calRecurrenceRule();
 
     NS_DECL_ISUPPORTS
-
     NS_DECL_CALIRECURRENCEITEM
-
     NS_DECL_CALIRECURRENCERULE
 protected:
+    icalrecurrencetype mIcalRecur;
+
     PRBool mImmutable;
     PRBool mIsNegative;
-
     PRBool mIsByCount;
-    struct icalrecurrencetype *mIcalRecur;
 };
 
-#endif
+#endif // INCLUDED_CAL_RECURRENCERULE_H
diff --git a/calendar/base/src/calTimezoneService.cpp b/calendar/base/src/calTimezoneService.cpp
new file mode 100644
index 00000000000..a4fccbd1e45
--- /dev/null
+++ b/calendar/base/src/calTimezoneService.cpp
@@ -0,0 +1,233 @@
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is Sun Microsystems code.
+ *
+ * The Initial Developer of the Original Code is
+ * Sun Microsystems, Inc.
+ * Portions created by the Initial Developer are Copyright (C) 2007
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Daniel Boelzle <daniel.boelzle@sun.com>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+#ifndef MOZILLA_1_8_BRANCH
+#include "nsIClassInfoImpl.h"
+#endif
+#include "calTimezoneService.h"
+#include "calUtils.h"
+#include "calIErrors.h"
+#include "calAttributeHelpers.h"
+
+NS_IMPL_ISUPPORTS1(calTimezone, calITimezone)
+
+CAL_ISUPPORTS_ATTR_GETTER(calTimezone, calIIcalComponent, Component)
+CAL_STRINGTYPE_ATTR_GETTER(calTimezone, nsACString, Tzid)
+CAL_STRINGTYPE_ATTR_GETTER(calTimezone, nsACString, Latitude)
+CAL_STRINGTYPE_ATTR_GETTER(calTimezone, nsACString, Longitude)
+CAL_VALUETYPE_ATTR_GETTER(calTimezone, PRBool, IsFloating)
+CAL_VALUETYPE_ATTR_GETTER(calTimezone, PRBool, IsUTC)
+
+NS_IMETHODIMP
+calTimezone::GetProvider(calITimezoneProvider ** _retval) {
+    NS_ENSURE_ARG_POINTER(_retval);
+    NS_ADDREF(*_retval = cal::getTimezoneService());
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+calTimezone::ToString(nsACString & aResult) {
+    // xxx todo remove: for some time, we want to know if a calITimezone object
+    //                  is treated as a string...
+    NS_WARNING("calTimezone::ToString called!");
+
+    if (mIsUTC || mIsFloating) {
+        aResult = mTzid;
+        return NS_OK;
+    }
+    return mComponent->ToString(aResult);
+}
+
+calTimezoneService::calTimezoneService()
+    : mUTC(new calTimezone(nsnull, NS_LITERAL_CSTRING("UTC"), PR_TRUE)),
+      mFloating(new calTimezone(nsnull, NS_LITERAL_CSTRING("floating"), PR_FALSE, PR_TRUE))
+{
+    mTzHash.Init();
+    mTzHash.Put(NS_LITERAL_CSTRING("UTC"), mUTC);
+    mTzHash.Put(NS_LITERAL_CSTRING("utc"), mUTC);
+    mTzHash.Put(NS_LITERAL_CSTRING("floating"), mFloating);
+}
+
+NS_IMPL_ISUPPORTS2_CI(calTimezoneService, calITimezoneProvider, calITimezoneService)
+
+CAL_ISUPPORTS_ATTR_GETTER(calTimezoneService, calITimezone, UTC)
+CAL_ISUPPORTS_ATTR_GETTER(calTimezoneService, calITimezone, Floating)
+
+// include tzdata, to get ical_timezone_data_struct
+#include "tzdata.c"
+
+static nsDependentCString sTzIdPrefix(kTzIdPrefix);
+
+NS_IMETHODIMP
+calTimezoneService::GetTimezone(nsACString const& tzid_, calITimezone ** _retval)
+{
+    NS_ENSURE_ARG_POINTER(_retval);
+    *_retval = nsnull;
+
+    if (!mTzHash.Get(tzid_, _retval) || !*_retval) {
+        nsCAutoString tzid;
+        if (NS_SUCCEEDED(LatestTzId(tzid_, tzid)) && StringBeginsWith(tzid, sTzIdPrefix)) {
+            // not found, look up in static tab:
+            for (PRUint32 i = 0; ical_timezone_data[i].tzid; ++i) {
+                if (tzid.Equals(ical_timezone_data[i].tzid)) {
+                    ical_timezone_data_struct const& tzdata = ical_timezone_data[i];
+                    nsCOMPtr<calIIcalComponent> icalComp, vtimezone;
+                    if (NS_FAILED(cal::getICSService()->ParseICS(nsDependentCString(tzdata.icstimezone),
+                                                                 nsnull,
+                                                                 getter_AddRefs(icalComp))) ||
+                        NS_FAILED(icalComp->GetFirstSubcomponent(NS_LITERAL_CSTRING("VTIMEZONE"),
+                                                                 getter_AddRefs(vtimezone))) ||
+                        !vtimezone) {
+                        NS_WARNING(ical_timezone_data[i].tzid);
+                        break;
+                    }
+                    nsCOMPtr<calITimezone> const tz(new calTimezone(vtimezone, tzid, PR_FALSE, PR_FALSE,
+                                                                    nsDependentCString(tzdata.latitude),
+                                                                    nsDependentCString(tzdata.longitude)));
+                    if (!mTzHash.Put(tzid, tz)) {
+                        return NS_ERROR_OUT_OF_MEMORY;
+                    }
+                    if (tzid_ != tzid) { // tzid has been updated by LatestTzId
+                        if (!mTzHash.Put(tzid_, tz)) {
+                            return NS_ERROR_OUT_OF_MEMORY;
+                        }
+                    }
+                    NS_ADDREF(*_retval = tz);
+                    break;
+                }
+            }
+        }
+    }
+    NS_ASSERTION(*_retval, PromiseFlatCString(tzid_).get());
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+calTimezoneService::GetTimezoneIds(nsIUTF8StringEnumerator ** aTzids)
+{
+    NS_ENSURE_ARG_POINTER(aTzids);
+    PRUint32 const arlen = sizeof(ical_timezone_data) / sizeof(ical_timezone_data[0]);
+    nsAutoPtr<nsCStringArray> pArray(new nsCStringArray(mTzHash.Count() + arlen));
+    CAL_ENSURE_MEMORY(pArray);
+    pArray->AppendCString(NS_LITERAL_CSTRING("UTC"));
+    for (PRUint32 i = 0; ical_timezone_data[i].tzid; ++i) {
+        pArray->AppendCString(nsDependentCString(ical_timezone_data[i].tzid));
+    }
+    pArray->Sort();
+    return cal::createUTF8StringEnumerator(pArray, aTzids);
+}
+
+NS_IMETHODIMP
+calTimezoneService::GetTzidPrefix(nsACString & _retval)
+{
+    _retval = sTzIdPrefix;
+    return NS_OK;
+}
+
+/**
+ * LatestTzId
+ * Gets updated timezone ID (tzId) for a given tzId.
+ * - If this isn't a mozilla.org tzId:
+ *      return nothing
+ * - If the tzId name was changed or the tzId was deleted:
+ *      return updated tzId
+ * - If the tzId's dtstamp is different from our current dtstamp:
+ *      return updated tzId
+ * - Otherwise, don't change the tzId.
+ */
+nsresult calTimezoneService::LatestTzId(const nsACString& tzid, nsACString& _retval) {
+    // Ensure _retval is both initialized and empty.
+    _retval.Truncate();
+
+    // If it doesn't start with "/mozilla.org/" then it isn't ours.
+    if (!StringBeginsWith(tzid, NS_LITERAL_CSTRING("/mozilla.org/"))) {
+        return NS_ERROR_INVALID_ARG;
+    }
+
+    // We know that our tzids look like "/mozilla.org/<dtstamp>/continent/..."
+    // The ending of the mozilla prefix is the index of that slash before the
+    // continent. Therefore, we start looking for the prefix-ending slash
+    // after position 13.
+    PRInt32 prefixEnd = tzid.FindChar('/', 13);
+    PRInt32 continentEnd = tzid.FindChar('/', prefixEnd + 1);
+
+    // Go through our list of deletions and changes in Olsen, and update
+    // these to entirely new zones.
+    nsCAutoString continent(Substring(tzid, prefixEnd + 1,
+                                      continentEnd - (prefixEnd + 1)));
+
+    // XXX We want to make this table-driven at some point in the future.
+// xxx todo => tz db generation code!
+    
+    if (continent.EqualsLiteral("Africa")) {
+        if (tzid.EqualsLiteral("/mozilla.org/20050126_1/Africa/Asmera")) {
+            _retval.AssignLiteral("/mozilla.org/20070129_1/Africa/Asmara");
+        } else if (tzid.EqualsLiteral("/mozilla.org/20050126_1/Africa/Timbuktu")) {
+            _retval.AssignLiteral("/mozilla.org/20070129_1/Africa/Bamako");
+        }
+    } else if (continent.EqualsLiteral("Atlantic")) {
+        if (tzid.EqualsLiteral("/mozilla.org/20050126_1/Atlantic/Faeroe")) {
+            _retval.AssignLiteral("/mozilla.org/20070129_1/Atlantic/Faroe");
+        }
+    } else if (continent.EqualsLiteral("America")) {
+        if (tzid.EqualsLiteral("/mozilla.org/20050126_1/America/Argentina/ComodRivadavia")) {
+            _retval.AssignLiteral("/mozilla.org/20070129_1/America/Argentina/Catamarca");
+        } else if (tzid.EqualsLiteral("/mozilla.org/20050126_1/America/Louisville")) {
+            _retval.AssignLiteral("/mozilla.org/20070129_1/America/Kentucky/Louisville");
+        }
+    } else if (continent.EqualsLiteral("Europe")) {
+        if (tzid.EqualsLiteral("/mozilla.org/20050126_1/Europe/Belfast")) {
+            _retval.AssignLiteral("/mozilla.org/20070129_1/Europe/London");
+        }
+    } else if (continent.EqualsLiteral("Pacific")) {
+        if (tzid.EqualsLiteral("/mozilla.org/20050126_1/Pacific/Yap")) {
+            _retval.AssignLiteral("/mozilla.org/20070129_1/Pacific/Truk");
+        }
+    }
+
+    if (_retval.IsEmpty()) {
+        if (sTzIdPrefix != Substring(tzid, 0, prefixEnd + 1)) {
+            // TODO: This assumes that new zones will always be later. If we are
+            // ever going to support mixing our TZID headers, then this needs to
+            // be a date comparison.
+            _retval = sTzIdPrefix;
+            _retval += Substring(tzid, prefixEnd + 1, tzid.Length() - (prefixEnd + 1));
+        } else {
+            _retval = tzid;
+        }
+    }
+    return NS_OK;
+}
diff --git a/calendar/base/src/calTimezoneService.h b/calendar/base/src/calTimezoneService.h
new file mode 100644
index 00000000000..68e7ea2c62e
--- /dev/null
+++ b/calendar/base/src/calTimezoneService.h
@@ -0,0 +1,96 @@
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is Sun Microsystems code.
+ *
+ * The Initial Developer of the Original Code is
+ * Sun Microsystems, Inc.
+ * Portions created by the Initial Developer are Copyright (C) 2007
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Daniel Boelzle <daniel.boelzle@sun.com>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+#if !defined(INCLUDED_CAL_TIMEZONESERVIC_H)
+#define INCLUDED_CAL_TIMEZONESERVIC_H
+
+#include "nsCOMPtr.h"
+#include "calITimezoneProvider.h"
+#include "nsInterfaceHashtable.h"
+#include "calUtils.h"
+
+extern "C" {
+#include "ical.h"
+}
+
+class calTimezone : public calITimezone,
+                    public cal::XpcomBase
+{
+public:
+    calTimezone(calIIcalComponent * component,
+                nsCString const& tzid,
+                PRBool isUTC = PR_FALSE,
+                PRBool isFloating = PR_FALSE,
+                nsCString const& latitude = nsCString(),
+                nsCString const& longitude = nsCString())
+        : mComponent(component),
+          mTzid(tzid),
+          mLatitude(latitude),
+          mLongitude(longitude),
+          mIsFloating(isFloating),
+          mIsUTC(isUTC) {}
+
+    NS_DECL_ISUPPORTS
+    NS_DECL_CALITIMEZONE
+
+private:
+    nsCOMPtr<calIIcalComponent> const mComponent;
+    nsCString const                   mTzid;
+    nsCString const                   mLatitude;
+    nsCString const                   mLongitude;
+    PRBool const                      mIsFloating;
+    PRBool const                      mIsUTC;
+};
+
+class calTimezoneService : public calITimezoneService,
+                           public cal::XpcomBase
+{
+public:
+    calTimezoneService();
+
+    NS_DECL_ISUPPORTS
+    NS_DECL_CALITIMEZONEPROVIDER
+    NS_DECL_CALITIMEZONESERVICE
+
+private:
+    nsresult LatestTzId(const nsACString& tzid, nsACString& _retval);
+
+    nsInterfaceHashtable<nsCStringHashKey, calITimezone> mTzHash;
+    nsCOMPtr<calITimezone> const mUTC;
+    nsCOMPtr<calITimezone> const mFloating;
+};
+
+#endif // INCLUDED_CAL_TIMEZONESERVIC_H
diff --git a/calendar/base/src/calUtils.cpp b/calendar/base/src/calUtils.cpp
index 7ea38ad6e26..26b8338d62d 100644
--- a/calendar/base/src/calUtils.cpp
+++ b/calendar/base/src/calUtils.cpp
@@ -34,15 +34,21 @@
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
-
-#ifndef MOZILLA_1_8_BRANCH
-#include "nsIClassInfoImpl.h"
-#endif
+#include "nsServiceManagerUtils.h"
+// #ifndef MOZILLA_1_8_BRANCH
+// #include "nsIClassInfoImpl.h"
+// #endif
+#include "calBaseCID.h"
 #include "calUtils.h"
 
+extern "C" {
+#include "ical.h"
+}
+
 namespace cal {
 
-class UTF8StringEnumerator : public nsIUTF8StringEnumerator
+class UTF8StringEnumerator : public nsIUTF8StringEnumerator,
+                             public XpcomBase
 {
 public:
     NS_DECL_ISUPPORTS
@@ -51,17 +57,10 @@ public:
     explicit UTF8StringEnumerator(nsAutoPtr<nsCStringArray> & takeOverArray)
         : mArray(takeOverArray), mPos(0) {}
 private:
-    UTF8StringEnumerator const& operator=(UTF8StringEnumerator const&);
-    virtual ~UTF8StringEnumerator();
-
     nsAutoPtr<nsCStringArray> const mArray;
     PRInt32 mPos;
 };
 
-UTF8StringEnumerator::~UTF8StringEnumerator()
-{
-}
-
 NS_IMPL_ISUPPORTS1(UTF8StringEnumerator, nsIUTF8StringEnumerator)
 
 NS_IMETHODIMP UTF8StringEnumerator::HasMore(PRBool *_retval)
@@ -88,10 +87,85 @@ nsresult createUTF8StringEnumerator(nsAutoPtr<nsCStringArray> & takeOverArray,
     NS_ENSURE_ARG_POINTER(takeOverArray.get());
     NS_ENSURE_ARG_POINTER(ppRet);
     *ppRet = new UTF8StringEnumerator(takeOverArray);
-    if (!*ppRet)
-        return NS_ERROR_OUT_OF_MEMORY;
+    CAL_ENSURE_MEMORY(*ppRet);
     NS_ADDREF(*ppRet);
     return NS_OK;
 }
 
+nsCOMPtr<calIICSService> const& getICSService() {
+    static nsCOMPtr<calIICSService> sIcsService;
+    if (!sIcsService) {
+        sIcsService = do_GetService(CAL_ICSSERVICE_CONTRACTID);
+        NS_ASSERTION(sIcsService, "Could not init ics service! Will crash now...");
+    }
+    return sIcsService;
+}
+
+nsCOMPtr<calITimezoneService> const& getTimezoneService() {
+    static nsCOMPtr<calITimezoneService> sTzService;
+    if (!sTzService) {
+        sTzService = do_GetService(CAL_TIMEZONESERVICE_CONTRACTID);
+        NS_ASSERTION(sTzService, "Could not init timezone service! Will crash now...");
+    }
+    return sTzService;
+}
+
+nsCOMPtr<calITimezone> const& floating() {
+    static nsCOMPtr<calITimezone> sFloating;
+    if (!sFloating) {
+        getTimezoneService()->GetFloating(getter_AddRefs(sFloating));
+    }
+    return sFloating;
+}
+
+nsCOMPtr<calITimezone> const& UTC() {
+    static nsCOMPtr<calITimezone> sUTC;
+    if (!sUTC) {
+        getTimezoneService()->GetUTC(getter_AddRefs(sUTC));
+    }
+    return sUTC;
+}
+
+nsCOMPtr<calITimezone> detectTimezone(icaltimetype const& icalt,
+                                      calITimezoneProvider * tzProvider)
+{
+    if (!tzProvider) {
+        tzProvider = getTimezoneService();
+    }
+    if (icalt.is_utc) {
+        return UTC();
+    }
+    if (icalt.zone) {
+        char const* const tzid = icaltimezone_get_tzid(const_cast<icaltimezone *>(icalt.zone));
+        if (tzid) {
+            nsCOMPtr<calITimezone> tz;
+            tzProvider->GetTimezone(nsDependentCString(tzid), getter_AddRefs(tz));
+            if (tz) {
+                return tz;
+            }
+            NS_ASSERTION(tz, "no timezone found, falling back to floating!");
+        }
+    }
+    return floating();
+}
+
+icaltimezone * getIcalTimezone(calITimezone * tz) {
+    icaltimezone * icaltz = nsnull;
+    PRBool b;
+    tz->GetIsUTC(&b);
+    if (b) {
+        icaltz = icaltimezone_get_utc_timezone();
+    } else {
+        nsCOMPtr<calIIcalComponent> tzComp;
+        tz->GetComponent(getter_AddRefs(tzComp));
+        if (tzComp) {
+            icaltz = tzComp->GetIcalTimezone();
+        } // else floating
+    }
+    return icaltz;
+}
+
+XpcomBase::~XpcomBase() {
+}
+
 }
diff --git a/calendar/base/src/calUtils.h b/calendar/base/src/calUtils.h
index 005ce5d8fad..ad96492c993 100644
--- a/calendar/base/src/calUtils.h
+++ b/calendar/base/src/calUtils.h
@@ -51,13 +51,95 @@
 #include "nsVoidArray.h"
 #include "nsIStringEnumerator.h"
 
+#include "calITimezoneProvider.h"
+#include "calIICSService.h"
+#include "nsCOMPtr.h"
+
+#define CAL_STRLEN_ARGS(x) x, sizeof(x)-1
 #define CAL_ENSURE_MEMORY(p) NS_ENSURE_TRUE(p, NS_ERROR_OUT_OF_MEMORY)
 
+typedef struct _icaltimezone icaltimezone;
+typedef struct icaltimetype icaltimetype;
+
 namespace cal {
 
+/**
+ * Creates a UTF8 string enumerator.
+ *
+ * @param takeOverArray      a C string array that is taken over by the resulting
+ *                           string enumerator object (nsAutoPtr passes over ownership)
+ * @param ppRet              returned enumerator object
+ */
 nsresult createUTF8StringEnumerator(nsAutoPtr<nsCStringArray> & takeOverArray,
                                     nsIUTF8StringEnumerator ** ppRet);
 
+// some static timezone helpers, we leak those, but this is ok since the
+// underlying service leaks those anyway until process termination
+
+/**
+ * Gets the global ICS service.
+ */
+nsCOMPtr<calIICSService> const& getICSService();
+
+/**
+ * Gets the global timezone service.
+ */
+nsCOMPtr<calITimezoneService> const& getTimezoneService();
+
+/**
+ * Gets the "floating" timezone
+ */
+nsCOMPtr<calITimezone> const& floating();
+
+/**
+ * Gets the "UTC" timezone.
+ */
+nsCOMPtr<calITimezone> const& UTC();
+
+/**
+ * Returns the libical VTIMEZONE component, null if floating.
+ * 
+ * @attention
+ * Every timezone provider needs to use calICSService for
+ * creating its timezone components since we need to stick to the
+ * same libical.
+ */    
+icaltimezone * getIcalTimezone(calITimezone * tz);
+
+/**
+ * Detects the timezone icalt refers to, either using the
+ * passed timezone provider or the global timezone service.
+ *
+ * @param icalt      an icaltime
+ * @param tzProvider timezone provider or null which
+ *                   defaults to the timezone service
+ */
+nsCOMPtr<calITimezone> detectTimezone(icaltimetype const& icalt,
+                                      calITimezoneProvider * tzProvider);
+
+/**
+ * Tests whether two interface pointers refer to the same object.
+ */
+inline NSCAP_BOOL sameXpcomObject(nsISupports * i1_, nsISupports * i2_) {
+    nsCOMPtr<nsISupports> const i1 = do_QueryInterface(i1_);
+    nsCOMPtr<nsISupports> const i2 = do_QueryInterface(i2_);
+    return i1 == i2;
 }
 
+/**
+ * Common base class for XPCOM object implementations:
+ * - disallows public deletion (virtual protected dtor)
+ * - disallows copy semantics (no assignment, no copy ctor)
+ */
+class XpcomBase {
+protected:
+    XpcomBase() {}
+    virtual ~XpcomBase();
+private:
+    XpcomBase(XpcomBase const&); // left unimplemented
+    XpcomBase const& operator=(XpcomBase const&); // left unimplemented
+};
+
+} // namespace cal
+
 #endif // !defined(INCLUDED_CAL_UTILS_H)
diff --git a/calendar/base/src/calUtils.js b/calendar/base/src/calUtils.js
index fa2eb6d374d..07062d3f325 100644
--- a/calendar/base/src/calUtils.js
+++ b/calendar/base/src/calUtils.js
@@ -81,8 +81,36 @@ function createAttendee() {
 
 /* Shortcut to the calendar-manager service */
 function getCalendarManager() {
-    return Components.classes["@mozilla.org/calendar/manager;1"].
-           getService(Components.interfaces.calICalendarManager);
+    if (getCalendarManager.mObject === undefined) {
+        getCalendarManager.mObject = Components.classes["@mozilla.org/calendar/manager;1"]
+                                               .getService(Components.interfaces.calICalendarManager);
+    }
+    return getCalendarManager.mObject;
+}
+
+/* Shortcut to the timezone service */
+function getTimezoneService() {
+    if (getTimezoneService.mObject === undefined) {
+        getTimezoneService.mObject = Components.classes["@mozilla.org/calendar/timezone-service;1"]
+                                               .getService(Components.interfaces.calITimezoneService);
+    }
+    return getTimezoneService.mObject;
+}
+
+/// @return the UTC timezone.
+function UTC() {
+    if (UTC.mObject === undefined) {
+        UTC.mObject = getTimezoneService().UTC;
+    }
+    return UTC.mObject;
+}
+
+/// @return the floating timezone.
+function floating() {
+    if (floating.mObject === undefined) {
+        floating.mObject = getTimezoneService().floating;
+    }
+    return floating.mObject;
 }
 
 /**
@@ -90,26 +118,23 @@ function getCalendarManager() {
  * use the value of the calendar.timezone.local preference, if it exists.  If
  * not, we'll do our best guess.
  *
- * @returns  a string of the Mozilla TZID for the user's default timezone.
+ * @return user's default timezone.
  */
-var gDefaultTimezone;
 function calendarDefaultTimezone() {
-    if (!gDefaultTimezone) {
-        gDefaultTimezone = getPrefSafe("calendar.timezone.local", null);
-        if (!gDefaultTimezone) {
-            gDefaultTimezone = guessSystemTimezone();
-        } else {
-            var icsSvc = Components.classes["@mozilla.org/calendar/ics-service;1"].
-                         getService(Components.interfaces.calIICSService);
-
-            // Update this tzid if necessary.
-            if (icsSvc.latestTzId(gDefaultTimezone).length) {
-                gDefaultTimezone = icsSvc.latestTzId(gDefaultTimezone);
-                setPref("calendar.timezone.local", "CHAR", gDefaultTimezone);
-            }
+    if (calendarDefaultTimezone.mTz === undefined) {
+        var prefTzid = getPrefSafe("calendar.timezone.local", null);
+        var tzid = prefTzid;
+        if (!tzid) {
+            tzid = guessSystemTimezone();
+        }
+        calendarDefaultTimezone.mTz = getTimezoneService().getTimezone(tzid);
+        ASSERT(calendarDefaultTimezone.mTz, "timezone not found: " + tzid);
+        // Update prefs if necessary:
+        if (calendarDefaultTimezone.mTz && calendarDefaultTimezone.mTz.tzid != prefTzid) {
+            setPref("calendar.timezone.local", "CHAR", calendarDefaultTimezone.mTz.tzid);
         }
     }
-    return gDefaultTimezone;
+    return calendarDefaultTimezone.mTz;
 }
 
 /**
@@ -157,14 +182,11 @@ function guessSystemTimezone() {
         dump("TZname1: " + TZname1 + "\nTZname2: " + TZname2 + "\n");
     }
 
-    var icsSvc = Components.classes["@mozilla.org/calendar/ics-service;1"].
-                 getService(Components.interfaces.calIICSService);
-
     // returns 0=definitely not, 1=maybe, 2=likely
     function checkTZ(someTZ)
     {
-        var comp = icsSvc.getTimezone(someTZ);
-        var subComp = comp.getFirstSubcomponent("VTIMEZONE");
+        var tz = getTimezoneService().getTimezone(someTZ);
+        var subComp = tz.component;
         var standard = subComp.getFirstSubcomponent("STANDARD");
         var standardTZOffset = standard.getFirstProperty("TZOFFSETTO").valueAsIcalString;
         var standardNameProp = standard.getFirstProperty("TZNAME");
@@ -223,8 +245,7 @@ function guessSystemTimezone() {
             // This happens if the l10n team didn't know how to get a time from
             // tzdata.c.  To convert an Olson time to a ics-timezone-string we
             // need to append this prefix.
-            // XXX Get this prefix from calIICSService.tzIdPrefix
-            stringBundleTZ = "/mozilla.org/20070129_1/" + stringBundleTZ;
+            stringBundleTZ = getTimezoneService().tzidPrefix + stringBundleTZ;
         }
 
         switch (checkTZ(stringBundleTZ)) {
@@ -241,7 +262,7 @@ function guessSystemTimezone() {
     catch (ex) { // Oh well, this didn't work, next option...
     }
         
-    var tzIDs = icsSvc.timezoneIds;
+    var tzIDs = getTimezoneService().timezoneIds;
     while (tzIDs.hasMore()) {
         var theTZ = tzIDs.getNext();
         try {
@@ -558,9 +579,18 @@ function compareItems(aItem, aOtherItem) {
  *
  * @param aObject        first object to be compared
  * @param aOtherObject   second object to be compared
- * @param aIID           IID to use in comparison
+ * @param aIID           IID to use in comparison, undefined/null defaults to nsISupports
  */
 function compareObjects(aObject, aOtherObject, aIID) {
+    // xxx todo: seems to work fine e.g. for WCAP, but I still mistrust this trickery...
+    //           Anybody knows an official API that could be used for this purpose?
+    //           For what reason do clients need to pass aIID since
+    //           every XPCOM object has to implement nsISupports?
+    //           XPCOM (like COM, like UNO, ...) defines that QueryInterface *only* needs to return
+    //           the very same pointer for nsISupports during its lifetime.
+    if (!aIID) {
+        aIID = Components.interfaces.nsISupports;
+    }
     var sip1 = Components.classes["@mozilla.org/supports-interface-pointer;1"].
                createInstance(Components.interfaces.nsISupportsInterfacePointer);
     sip1.data = aObject;
@@ -1297,9 +1327,6 @@ function sendMailTo(aRecipient, aSubject, aBody) {
     }
 }
 
-var gOpGroupPrefix;
-var gOpGroupId = 0;
-
 /**
  * This object implements calIOperation and could group multiple sub
  * operations into one. You can pass a cancel function which is called once
@@ -1312,12 +1339,14 @@ var gOpGroupId = 0;
  */
 function calOperationGroup(cancelFunc) {
     this.wrappedJSObject = this;
-    if (!gOpGroupPrefix) {
-        gOpGroupPrefix = (getUUID() + "-");
+    if (calOperationGroup.mOpGroupId === undefined) {
+        calOperationGroup.mOpGroupId = 0;
+    }
+    if (calOperationGroup.mOpGroupPrefix === undefined) {
+        calOperationGroup.mOpGroupPrefix = (getUUID() + "-");
     }
     this.mCancelFunc = cancelFunc;
-    this.mId = (gOpGroupPrefix + gOpGroupId);
-    ++gOpGroupId;
+    this.mId = (calOperationGroup.mOpGroupPrefix + calOperationGroup.mOpGroupId++);
     this.mSubOperations = [];
 }
 calOperationGroup.prototype = {
diff --git a/calendar/import-export/calIcsImportExport.js b/calendar/import-export/calIcsImportExport.js
index c4bb9e273ca..ea405a343f1 100644
--- a/calendar/import-export/calIcsImportExport.js
+++ b/calendar/import-export/calIcsImportExport.js
@@ -66,7 +66,7 @@ calIcsImporter.prototype.importFromStream =
 function ics_importFromStream(aStream, aCount) {
     var parser = Components.classes["@mozilla.org/calendar/ics-parser;1"].
                             createInstance(Components.interfaces.calIIcsParser);
-    parser.parseFromStream(aStream);
+    parser.parseFromStream(aStream, null);
     return parser.getItems(aCount);
 };
 
diff --git a/calendar/import-export/calOutlookCSVImportExport.js b/calendar/import-export/calOutlookCSVImportExport.js
index 44183c3f7c1..d4489dfcde5 100644
--- a/calendar/import-export/calOutlookCSVImportExport.js
+++ b/calendar/import-export/calOutlookCSVImportExport.js
@@ -326,7 +326,7 @@ function parseDateTime(aDate, aTime, aLocale)
                          .createInstance(Components.interfaces.calIDateTime);
 
     //XXX Can we do better?
-    date.timezone = "floating";
+    date.timezone = floating();
 
     var rd = aLocale.dateRe.exec(aDate);
     var rt = aLocale.timeRe.exec(aTime);
diff --git a/calendar/prototypes/wcap/sun-calendar-event-dialog-attendees.js b/calendar/prototypes/wcap/sun-calendar-event-dialog-attendees.js
index 4bfe94588c6..37fa87eec5a 100644
--- a/calendar/prototypes/wcap/sun-calendar-event-dialog-attendees.js
+++ b/calendar/prototypes/wcap/sun-calendar-event-dialog-attendees.js
@@ -139,7 +139,6 @@ function onLoad() {
 }
 
 function onAccept() {
-    var kDefaultTimezone = calendarDefaultTimezone();
     var attendees = document.getElementById("attendees-list");
     window.arguments[0].onOk(
         attendees.attendees,
@@ -235,8 +234,8 @@ function updateDateTime() {
         // the timezone of the endtime is "UTC", we convert
         // the endtime into the timezone of the starttime.
         if (startTime && endTime) {
-            if (startTime.timezone != endTime.timezone) {
-                if (endTime.timezone == "UTC") {
+            if (!compareObjects(startTime.timezone, endTime.timezone)) {
+                if (endTime.timezone.isUTC) {
                     endTime = endTime.getInTimezone(startTime.timezone);
                 }
             }
@@ -245,8 +244,8 @@ function updateDateTime() {
         // Before feeding the date/time value into the control we need
         // to set the timezone to 'floating' in order to avoid the
         // automatic conversion back into the OS timezone.
-        startTime.timezone = "floating";
-        endTime.timezone = "floating";
+        startTime.timezone = floating();
+        endTime.timezone = floating();
 
         document.getElementById("event-starttime").value = startTime.jsDate;
         document.getElementById("event-endtime").value = endTime.jsDate;
@@ -264,8 +263,8 @@ function updateDateTime() {
         // Before feeding the date/time value into the control we need
         // to set the timezone to 'floating' in order to avoid the
         // automatic conversion back into the OS timezone.
-        startTime.timezone = "floating";
-        endTime.timezone = "floating";
+        startTime.timezone = floating();
+        endTime.timezone = floating();
 
         document.getElementById("event-starttime").value = startTime.jsDate;
         document.getElementById("event-endtime").value = endTime.jsDate;
@@ -275,13 +274,13 @@ function updateDateTime() {
     updateAllDay();
 }
 
-function timezoneString(date) {
-    var fragments = date.split('/');
-    var num = fragments.length;
-    if (num <= 1) {
-        return fragments[0];
+function timezoneString(tz) {
+    var tzid = tz.tzid;
+    var prefix = getTimezoneService().tzidPrefix;
+    if (tzid.indexOf(prefix) == 0) {
+        tzid = tzid.substring(prefix.length);
     }
-    return fragments[num - 2] + '/' + fragments[num - 1];
+    return tzid;
 }
 
 /**
@@ -302,7 +301,7 @@ function updateTimezone() {
         var endTimezone = gEndTimezone;
         var equalTimezones = false;
         if (startTimezone && endTimezone &&
-            (startTimezone == endTimezone || endTimezone == "UTC")) {
+            (compareObjects(startTimezone, endTimezone) || endTimezone.isUTC)) {
             equalTimezones = true;
         }
 
@@ -381,9 +380,9 @@ function updateEndTime() {
                                   gDisplayTimezone ? gStartTimezone : calendarDefaultTimezone());
 
     var timezone = gEndTimezone;
-    if (timezone == "UTC" &&
+    if (timezone.isUTC &&
         gStartDate &&
-        gStartTimezone != gEndTimezone) {
+        !compareObjects(gStartTimezone, gEndTimezone)) {
         timezone = gStartTimezone;
     }
     gEndDate = jsDateToDateTime(endWidget.value,
@@ -436,13 +435,13 @@ function editStartTimezone() {
     args.time = gStartDate.getInTimezone(gStartTimezone);
     args.onOk = function(datetime) {
         var equalTimezones = false;
-        if (self.mStartTimezone && self.mEndTimezone &&
-            self.mStartTimezone == self.mEndTimezone) {
+        if (gStartTimezone && gEndTimezone &&
+            compareObjects(gStartTimezone, gEndTimezone)) {
             equalTimezones = true;
         }
-        self.mStartTimezone = datetime.timezone;
+        gStartTimezone = datetime.timezone;
         if (equalTimezones) {
-            self.mEndTimezone = datetime.timezone;
+            gEndTimezone = datetime.timezone;
         }
         self.propagateDateTime();
     };
@@ -465,15 +464,11 @@ function editEndTimezone() {
     var args = new Object();
     args.time = gEndTime.getInTimezone(gEndTimezone);
     args.onOk = function(datetime) {
-        var equalTimezones = false;
-        if (self.mStartTimezone && self.mEndTimezone &&
-            self.mStartTimezone == self.mEndTimezone) {
-            equalTimezones = true;
+        if (gStartTimezone && gEndTimezone &&
+            compareObjects(gStartTimezone, gEndTimezone)) {
+            gStartTimezone = datetime.timezone;
         }
-        if (equalTimezones) {
-            self.mStartTimezone = datetime.timezone;
-        }
-        self.mEndTimezone = datetime.timezone;
+        gEndTimezone = datetime.timezone;
         self.propagateDateTime();
     };
 
diff --git a/calendar/prototypes/wcap/sun-calendar-event-dialog-timezone.js b/calendar/prototypes/wcap/sun-calendar-event-dialog-timezone.js
index 84b0e8f1f3c..0bf8599bc29 100644
--- a/calendar/prototypes/wcap/sun-calendar-event-dialog-timezone.js
+++ b/calendar/prototypes/wcap/sun-calendar-event-dialog-timezone.js
@@ -39,13 +39,11 @@ function onLoad() {
     window.time = args.time;
     window.onAcceptCallback = args.onOk;
 
-    var tzname = timezoneString(window.time.timezone);
+    var tzname = timezoneString(window.time.timezone.tzid);
     var menulist = document.getElementById("timezone-menulist");
     var index = findTimezone(tzname);
     if (index < 0) {
-        var kDefaultTimezone = calendarDefaultTimezone();
-        var tzstring = window.time.getInTimezone(kDefaultTimezone).timezone;
-        tzname = timezoneString(tzstring);
+        tzname = timezoneString(calendarDefaultTimezone().tzid);
         index = findTimezone(tzname);
     }
 
@@ -69,19 +67,19 @@ function findTimezone(timezone) {
     return -1;
 }
 
-function timezoneString(timezone) {
-    var fragments = timezone.split('/');
-    var num = fragments.length;
-    if (num <= 1) {
-        return fragments[0];
+function timezoneString(tzid) {
+    var prefix = getTimezoneService().tzidPrefix;
+    if (tzid.indexOf(prefix) == 0) {
+        tzid = tzid.substring(prefix.length);
     }
-    return fragments[num-2] + '/' + fragments[num - 1];
+    return tzid;
 }
 
 function updateTimezone() {
     var menulist = document.getElementById("timezone-menulist");
     var menuitem = menulist.selectedItem;
     var someTZ = menuitem.getAttribute("value");
+    var tz = getTimezoneService().getTimezone(someTZ);
 
     // convert the date/time to the currently selected timezone
     // and display the result in the appropriate control.
@@ -89,15 +87,11 @@ function updateTimezone() {
     // to set the timezone to 'floating' in order to avoid the
     // automatic conversion back into the OS timezone.
     var datetime = document.getElementById("timezone-time");
-    var time = window.time.getInTimezone(someTZ);
-    time.timezone = "floating";
+    var time = window.time.getInTimezone(tz);
+    time.timezone = floating();
     datetime.value = time.jsDate;
 
-    var icssrv = Components.classes["@mozilla.org/calendar/ics-service;1"]
-                 .getService(Components.interfaces.calIICSService);
-
-    var comp = icssrv.getTimezone(someTZ);
-    var subComp = comp.getFirstSubcomponent("VTIMEZONE");
+    var subComp = tz.component;
     var standard = subComp.getFirstSubcomponent("STANDARD");
     var standardTZOffset = standard.getFirstProperty("TZOFFSETTO").valueAsIcalString;
 
@@ -120,7 +114,8 @@ function onAccept() {
     var menulist = document.getElementById("timezone-menulist");
     var menuitem = menulist.selectedItem;
     var timezone = menuitem.getAttribute("value");
-    var datetime = window.time.getInTimezone(timezone);
+    var tz = getTimezoneService().getTimezone(timezone);
+    var datetime = window.time.getInTimezone(tz);
     window.onAcceptCallback(datetime);
     return true;
 }
diff --git a/calendar/prototypes/wcap/sun-calendar-event-dialog.js b/calendar/prototypes/wcap/sun-calendar-event-dialog.js
index 711dd539b3c..a1389d57993 100644
--- a/calendar/prototypes/wcap/sun-calendar-event-dialog.js
+++ b/calendar/prototypes/wcap/sun-calendar-event-dialog.js
@@ -271,13 +271,13 @@ function onCancel() {
     return result;
 }
 
-function timezoneString(aDate) {
-    var fragments = aDate.split('/');
-    var num = fragments.length;
-    if (num <= 1) {
-        return fragments[0];
+function timezoneString(tz) {
+    var tzid = tz.tzid;
+    var prefix = getTimezoneService().tzidPrefix;
+    if (tzid.indexOf(prefix) == 0) {
+        tzid = tzid.substring(prefix.length);
     }
-    return fragments[num-2] + '/'+fragments[num - 1];
+    return tzid;
 }
 
 function loadDialog(item) {
@@ -448,6 +448,7 @@ function loadDialog(item) {
 }
 
 function loadDateTime(item) {
+    var kDefaultTimezone = calendarDefaultTimezone();
     if (isEvent(item)) {
         var startTime = item.startDate;
         var endTime = item.endDate;
@@ -465,7 +466,6 @@ function loadDateTime(item) {
         // store the start/end-times as calIDateTime-objects
         // converted to the default timezone. store the timezones
         // separately.
-        var kDefaultTimezone = calendarDefaultTimezone();
         gStartTimezone = startTime.timezone;
         gEndTimezone = endTime.timezone;
         gStartTime = startTime.getInTimezone(kDefaultTimezone);
@@ -478,7 +478,6 @@ function loadDateTime(item) {
         var endTime = null;
         var duration = null;
 
-        var kDefaultTimezone = calendarDefaultTimezone();
         var hasEntryDate = (item.entryDate != null);
         if (hasEntryDate) {
             startTime = item.entryDate;
@@ -550,8 +549,8 @@ function dateTimeControls2State(aKeepDuration) {
             }
         } else {
             var timezone = gEndTimezone;
-            if (timezone == "UTC") {
-                if (gStartTime && gStartTimezone != gEndTimezone) {
+            if (timezone.isUTC) {
+                if (gStartTime && !compareObjects(gStartTimezone, gEndTimezone)) {
                     timezone = gStartTimezone;
                 }
             }
@@ -953,8 +952,8 @@ function updateAccept() {
         if (menuItem.getAttribute('checked') == 'true') {
             var startTimezone = gStartTimezone;
             var endTimezone = gEndTimezone;
-            if (endTimezone == "UTC") {
-                if (gStartTimezone != gEndTimezone) {
+            if (endTimezone.isUTC) {
+                if (!compareObjects(gStartTimezone, gEndTimezone)) {
                     endTimezone = gStartTimezone;
                 }
             }
@@ -1318,7 +1317,7 @@ function setItemProperty(item, propertyName, value) {
         case "startDate":
             if (value.isDate && !item.startDate.isDate ||
                 !value.isDate && item.startDate.isDate ||
-                value.timezone != item.startDate.timezone ||
+                !compareObjects(value.timezone, item.startDate.timezone) ||
                 value.compare(item.startDate) != 0) {
                 item.startDate = value;
             }
@@ -1326,7 +1325,7 @@ function setItemProperty(item, propertyName, value) {
         case "endDate":
             if (value.isDate && !item.endDate.isDate ||
                 !value.isDate && item.endDate.isDate ||
-                value.timezone != item.endDate.timezone ||
+                !compareObjects(value.timezone, item.endDate.timezone) ||
                 value.compare(item.endDate) != 0) {
                 item.endDate = value;
             }
@@ -1338,7 +1337,7 @@ function setItemProperty(item, propertyName, value) {
             if (value && !item.entryDate ||
                 !value && item.entryDate ||
                 value.isDate != item.entryDate.isDate ||
-                value.timezone != item.entryDate.timezone ||
+                !compareObjects(value.timezone, item.entryDate.timezone) ||
                 value.compare(item.entryDate) != 0) {
                 item.entryDate = value;
             }
@@ -1350,7 +1349,7 @@ function setItemProperty(item, propertyName, value) {
             if (value && !item.dueDate ||
                 !value && item.dueDate ||
                 value.isDate != item.dueDate.isDate ||
-                value.timezone != item.dueDate.timezone ||
+                !compareObjects(value.timezone, item.dueDate.timezone) ||
                 value.compare(item.dueDate) != 0) {
                 item.dueDate = value;
             }
@@ -1871,7 +1870,7 @@ function editEndTimezone() {
         function(datetime) {
             var equalTimezones = false;
             if (gStartTimezone && gEndTimezone) {
-                if (gStartTimezone == gEndTimezone) {
+                if (compareObjects(gStartTimezone, gEndTimezone)) {
                     equalTimezones = true;
                 }
             }
@@ -1937,8 +1936,8 @@ function updateDateTime() {
           // the timezone of the endtime is "UTC", we convert
           // the endtime into the timezone of the starttime.
           if (startTime && endTime) {
-            if (startTime.timezone != endTime.timezone) {
-              if (endTime.timezone == "UTC") {
+            if (!compareObjects(startTime.timezone, endTime.timezone)) {
+              if (endTime.timezone.isUTC) {
                 endTime = endTime.getInTimezone(startTime.timezone);
               }
             }
@@ -1947,8 +1946,8 @@ function updateDateTime() {
           // before feeding the date/time value into the control we need
           // to set the timezone to 'floating' in order to avoid the
           // automatic conversion back into the OS timezone.
-          startTime.timezone = "floating";
-          endTime.timezone = "floating";
+          startTime.timezone = floating();
+          endTime.timezone = floating();
 
           setElementValue("event-starttime", startTime.jsDate);
           setElementValue("event-endtime", endTime.jsDate);
@@ -1962,25 +1961,25 @@ function updateDateTime() {
 
           if (hasEntryDate && hasDueDate) {
               setElementValue("todo-has-entrydate", hasEntryDate, "checked");
-              startTime.timezone = "floating";
+              startTime.timezone = floating();
               setElementValue("todo-entrydate", startTime.jsDate);
 
               setElementValue("todo-has-duedate", hasDueDate, "checked");
-              endTime.timezone = "floating";
+              endTime.timezone = floating();
               setElementValue("todo-duedate", endTime.jsDate);
           } else if (hasEntryDate) {
               setElementValue("todo-has-entrydate", hasEntryDate, "checked");
-              startTime.timezone = "floating";
+              startTime.timezone = floating();
               setElementValue("todo-entrydate", startTime.jsDate);
 
-              startTime.timezone = "floating";
+              startTime.timezone = floating();
               setElementValue("todo-duedate", startTime.jsDate);
           } else if (hasDueDate) {
-              endTime.timezone = "floating";
+              endTime.timezone = floating();
               setElementValue("todo-entrydate", endTime.jsDate);
 
               setElementValue("todo-has-duedate", hasDueDate, "checked");
-              endTime.timezone = "floating";
+              endTime.timezone = floating();
               setElementValue("todo-duedate", endTime.jsDate);
           }
         }
@@ -1995,8 +1994,8 @@ function updateDateTime() {
             // before feeding the date/time value into the control we need
             // to set the timezone to 'floating' in order to avoid the
             // automatic conversion back into the OS timezone.
-            startTime.timezone = "floating";
-            endTime.timezone = "floating";
+            startTime.timezone = floating();
+            endTime.timezone = floating();
             setElementValue("event-starttime", startTime.jsDate);
             setElementValue("event-endtime", endTime.jsDate);
         }
@@ -2010,25 +2009,25 @@ function updateDateTime() {
 
             if (hasEntryDate && hasDueDate) {
                 setElementValue("todo-has-entrydate", hasEntryDate, "checked");
-                startTime.timezone = "floating";
+                startTime.timezone = floating();
                 setElementValue("todo-entrydate", startTime.jsDate);
 
                 setElementValue("todo-has-duedate", hasDueDate, "checked");
-                endTime.timezone = "floating";
+                endTime.timezone = floating();
                 setElementValue("todo-duedate", endTime.jsDate);
             } else if (hasEntryDate) {
                 setElementValue("todo-has-entrydate", hasEntryDate, "checked");
-                startTime.timezone = "floating";
+                startTime.timezone = floating();
                 setElementValue("todo-entrydate", startTime.jsDate);
 
-                startTime.timezone = "floating";
+                startTime.timezone = floating();
                 setElementValue("todo-duedate", startTime.jsDate);
             } else if (hasDueDate) {
-                endTime.timezone = "floating";
+                endTime.timezone = floating();
                 setElementValue("todo-entrydate", endTime.jsDate);
 
                 setElementValue("todo-has-duedate", hasDueDate, "checked");
-                endTime.timezone = "floating";
+                endTime.timezone = floating();
                 setElementValue("todo-duedate", endTime.jsDate);
             }
         }
@@ -2058,7 +2057,7 @@ function updateTimezone() {
 
         var equalTimezones = false;
         if (startTimezone && endTimezone) {
-            if (startTimezone == endTimezone || endTimezone == "UTC") {
+            if (compareObjects(startTimezone, endTimezone) || endTimezone.isUTC) {
                 equalTimezones = true;
             }
         }
diff --git a/calendar/providers/caldav/calDavCalendar.js b/calendar/providers/caldav/calDavCalendar.js
index ad61202ab25..2179fa977ec 100644
--- a/calendar/providers/caldav/calDavCalendar.js
+++ b/calendar/providers/caldav/calDavCalendar.js
@@ -904,7 +904,7 @@ calDavCalendar.prototype = {
                     thisCalendar.mICSService = Components.classes["@mozilla.org/calendar/ics-service;1"].
                                                getService(Components.interfaces.calIICSService);
                 }
-                var rootComp = thisCalendar.mICSService.parseICS(calData);
+                var rootComp = thisCalendar.mICSService.parseICS(calData, null);
 
                 var calComp;
                 if (rootComp.componentType == 'VCALENDAR') {
@@ -1222,8 +1222,8 @@ calDavCalendar.prototype = {
                 queryRangeEnd.day++;
                 queryRangeEnd.isDate = false;
             }
-            var rangeXml = <time-range start={queryRangeStart.getInTimezone("UTC").icalString}
-                                       end={queryRangeEnd.getInTimezone("UTC").icalString}/>;
+            var rangeXml = <time-range start={queryRangeStart.getInTimezone(UTC()).icalString}
+                                       end={queryRangeEnd.getInTimezone(UTC()).icalString}/>;
 
         }
 
@@ -1671,9 +1671,9 @@ calDavCalendar.prototype = {
 
         var organizer = this.mMailToUrl;
 
-        var dtstamp = now().getInTimezone("UTC").icalString;
-        var dtstart = aRangeStart.getInTimezone("UTC").icalString;
-        var dtend = aRangeEnd.getInTimezone("UTC").icalString;
+        var dtstamp = now().getInTimezone(UTC()).icalString;
+        var dtstart = aRangeStart.getInTimezone(UTC()).icalString;
+        var dtend = aRangeEnd.getInTimezone(UTC()).icalString;
         var uuid = getUUID();
 
         var fbQuery = "BEGIN:VCALENDAR\n";
diff --git a/calendar/providers/gdata/components/calGoogleCalendar.js b/calendar/providers/gdata/components/calGoogleCalendar.js
index cdde7c854d3..47aac916bd2 100644
--- a/calendar/providers/gdata/components/calGoogleCalendar.js
+++ b/calendar/providers/gdata/components/calGoogleCalendar.js
@@ -677,7 +677,7 @@ calGoogleCalendar.prototype = {
             var xml = new XML(aItemString.substring(38));
 
             // Get the local timezone from the preferences
-            var timezone = getPrefSafe("calendar.timezone.local");
+            var timezone = calendarDefaultTimezone().tzid;
 
             // Parse the Item with the given timezone
             var item = XMLEntryToItem(xml, timezone, this.superCalendar);
diff --git a/calendar/providers/gdata/components/calGoogleCalendarModule.js b/calendar/providers/gdata/components/calGoogleCalendarModule.js
index 4a292b6144c..4a7ff8cbe9d 100644
--- a/calendar/providers/gdata/components/calGoogleCalendarModule.js
+++ b/calendar/providers/gdata/components/calGoogleCalendarModule.js
@@ -74,7 +74,7 @@ function ComponentsUtilsImport(aFile) {
         var scriptUri = iosvc.newFileURI(aFile);
         loader.loadSubScript(scriptUri.spec, null);
     } catch (e) {
-        Components.utils.reportError("Error while loading " + fileurl.spec);
+        Components.utils.reportError("Error while loading " + aFile.path);
         throw e;
     }
 }
diff --git a/calendar/providers/gdata/components/calGoogleUtils.js b/calendar/providers/gdata/components/calGoogleUtils.js
index 4905124f582..df93e95ff74 100644
--- a/calendar/providers/gdata/components/calGoogleUtils.js
+++ b/calendar/providers/gdata/components/calGoogleUtils.js
@@ -210,29 +210,30 @@ function getCalendarCredentials(aCalendarName,
  * @return              The same string including /mozilla.org/<date>/
  */
 function getMozillaTimezone(aICALTimezone) {
-
-    if (!aICALTimezone ||
-        aICALTimezone == "UTC" ||
-        aICALTimezone == "floating") {
-        return aICALTimezone;
+    ASSERT(aICALTimezone, "No timezone passed", true);
+    if (aICALTimezone == "floating") {
+        return floating();
+    } else if (aICALTimezone == "UTC") {
+        return UTC();
     }
+
     // TODO A patch to Bug 363191 should make this more efficient.
     // For now we need to go through all timezones and see which timezone
     // ends with aICALTimezone.
 
-    var icsSvc = Components.classes["@mozilla.org/calendar/ics-service;1"].
-                 getService(Components.interfaces.calIICSService);
-
+    var tzService = getTimezoneService();
     // Enumerate timezones, set them, check their offset
-    var enumerator = icsSvc.timezoneIds;
+    var enumerator = tzService.timezoneIds;
+    var id = null;
     while (enumerator.hasMore()) {
-        var id = enumerator.getNext();
+        id = enumerator.getNext();
 
         if (id.substr(-aICALTimezone.length) == aICALTimezone) {
-            return id;
+            return tzService.getTimezone(id);
         }
     }
-    return null;
+
+    return floating();
 }
 
 /**
@@ -257,7 +258,7 @@ function fromRFC3339(aStr, aTimezone) {
         "(([Zz]|([+-])([0-9]{2}):([0-9]{2})))?");
 
     var matches = re.exec(aStr);
-    var moztz = getMozillaTimezone(aTimezone) || "UTC";
+    var moztz = getMozillaTimezone(aTimezone);
 
     if (!matches) {
         return null;
@@ -280,7 +281,7 @@ function fromRFC3339(aStr, aTimezone) {
     if (matches[9] == "Z") {
         // If the dates timezone is "Z", then this is UTC, no matter
         // what timezone was passed
-        dateTime.timezone = "UTC";
+        dateTime.timezone = UTC();
 
     } else if (matches[9] == null) {
         // We have no timezone info, only a date. We have no way to
@@ -302,21 +303,19 @@ function fromRFC3339(aStr, aTimezone) {
         if (dateTime.timezoneOffset != offset_in_s) {
             // TODO A patch to Bug 363191 should make this more efficient.
 
-            var icsSvc = Components.classes["@mozilla.org/calendar/ics-service;1"].
-                         getService(Components.interfaces.calIICSService);
-
+			var tzService = getTimezoneService();
             // Enumerate timezones, set them, check their offset
-            var enumerator = icsSvc.timezoneIds;
+            var enumerator = tzService.timezoneIds;
             while (enumerator.hasMore()) {
                 var id = enumerator.getNext();
-                dateTime.timezone = id;
+                dateTime.timezone = tzService.getTimezone(id);
                 if (dateTime.timezoneOffset == offset_in_s) {
                     // This is our last step, so go ahead and return
                     return dateTime;
                 }
             }
             // We are still here: no timezone was found
-            dateTime.timezone = "UTC";
+            dateTime.timezone = UTC();
             if (!dateTime.isDate) {
                 dateTime.hour += (matches[11] == "-" ? -1 : 1) * matches[12];
                 dateTime.minute += (matches[11] == "-" ? -1 : 1) * matches[13];
@@ -358,7 +357,7 @@ function toRFC3339(aDateTime) {
             str += (tzoffset_hr < 0 ? "-" : "+") +
                    ("00" + Math.abs(tzoffset_hr)).substr(-2) + ":" +
                    ("00" + Math.abs(tzoffset_mn)).substr(-2);
-        } else if (aDateTime.timezone == "floating") {
+        } else if (aDateTime.timezone.isFloating) {
             // RFC3339 Section 4.3 Unknown Local Offset Convention
             str += "-00:00";
         } else {
@@ -1037,7 +1036,6 @@ function XMLEntryToItem(aXMLEntry, aTimezone, aCalendar) {
         // those recurrence events.
         // XXX This code is somewhat preliminary
 
-        var timezone;
         var startDate = createDateTime();
         var endDate;
         for each (var line in lines) {
diff --git a/calendar/providers/ics/calICSCalendar.js b/calendar/providers/ics/calICSCalendar.js
index 51840001132..abfbdcb5a0f 100644
--- a/calendar/providers/ics/calICSCalendar.js
+++ b/calendar/providers/ics/calICSCalendar.js
@@ -228,7 +228,7 @@ calICSCalendar.prototype = {
         try {
             var parser = Components.classes["@mozilla.org/calendar/ics-parser;1"].
                                     createInstance(Components.interfaces.calIIcsParser);
-            parser.parseString(str);
+            parser.parseString(str, null);
             var items = parser.getItems({});
             
             for each (var item in items) {
diff --git a/calendar/providers/storage/calStorageCalendar.js b/calendar/providers/storage/calStorageCalendar.js
index 6be3b5dd5b4..abae2c1096d 100644
--- a/calendar/providers/storage/calStorageCalendar.js
+++ b/calendar/providers/storage/calStorageCalendar.js
@@ -148,12 +148,12 @@ function textToDate(d) {
 function dateToText(d) {
     var datestr;
     var tz = null;
-    if (d.timezone != "floating") {
-        if (d.timezone == "UTC") {
+    if (!d.timezone.isFloating) {
+        if (d.timezone.isUTC) {
             datestr = "U";
         } else {
             datestr = "Z";
-            tz = d.timezone;
+            tz = d.timezone.tzid;
         }
     } else {
         datestr = "L";
@@ -183,10 +183,11 @@ function dateToText(d) {
 function newDateTime(aNativeTime, aTimezone) {
     var t = createDateTime();
     t.nativeTime = aNativeTime;
-    if (aTimezone && aTimezone != "floating") {
-        t = t.getInTimezone(aTimezone);
+    if (aTimezone) {
+        var tz = getTimezoneService().getTimezone(aTimezone);
+        t = t.getInTimezone(tz);
     } else {
-        t.timezone = "floating";
+        t.timezone = floating();
     }
 
     return t;
@@ -1756,7 +1757,7 @@ calStorageCalendar.prototype = {
     setDateParamHelper: function (params, entryname, cdt) {
         if (cdt) {
             params[entryname] = cdt.nativeTime;
-            params[entryname + "_tz"] = cdt.timezone;
+            params[entryname + "_tz"] = cdt.timezone.tzid;
         } else {
             params[entryname] = null;
             params[entryname + "_tz"] = null;
diff --git a/calendar/providers/wcap/calWcapCalendar.js b/calendar/providers/wcap/calWcapCalendar.js
index 6db629c4c75..28426974fc7 100644
--- a/calendar/providers/wcap/calWcapCalendar.js
+++ b/calendar/providers/wcap/calWcapCalendar.js
@@ -396,15 +396,19 @@ calWcapCalendar.prototype = {
         return tzid[0];
     },
     
-    getAlignedTimezone: function calWcapCalendar_getAlignedTimezone(tzid) {
-        // check whether it is one of cs:
-        if (tzid.indexOf("/mozilla.org/") == 0) {
-            // cut mozilla prefix: assuming that the latter string portion
-            //                     semantically equals the demanded timezone
-            tzid = tzid.substring( // next slash after "/mozilla.org/"
-                tzid.indexOf("/", "/mozilla.org/".length) + 1);
+    getAlignedTzid: function calWcapCalendar_getAlignedTzid(tz) {
+        var tzid = tz.tzid;
+        // check whether it is one cs supports:
+        if (!tz.isUTC && !tz.isFloating && !compareObjects(tz.provider, this.session)) {
+            log("not a server timezone: " + tzid);
+            var prefix = getTimezoneService().tzidPrefix;
+            if (tzid.indexOf(prefix) == 0) {
+                // cut mozilla prefix: assuming that the latter string portion
+                //                     semantically equals the demanded timezone
+                tzid = tzid.substring(prefix.length);
+            }
         }
-        if (!this.session.isSupportedTimezone(tzid)) {
+        if (!this.session.getTimezone(tzid)) {
             // xxx todo: we could further on search for a matching region,
             //           e.g. CET (in TZNAME), but for now stick to
             //           user's default if not supported directly
@@ -413,8 +417,7 @@ calWcapCalendar.prototype = {
             log(tzid + " not supported, falling back to default: " + ret, this);
             return ret;
         }
-        else // is ok (supported):
-            return tzid;
+        return tzid;
     },
     
     checkAccess: function calWcapCalendar_checkAccess(accessControlBits)
diff --git a/calendar/providers/wcap/calWcapCalendarItems.js b/calendar/providers/wcap/calWcapCalendarItems.js
index ecb17a41e79..d4bdd9b5355 100644
--- a/calendar/providers/wcap/calWcapCalendarItems.js
+++ b/calendar/providers/wcap/calWcapCalendarItems.js
@@ -68,10 +68,10 @@ calWcapCalendar.prototype.encodeNscpTzid =
 function calWcapCalendar_encodeNscpTzid(dateTime)
 {
     var params = "X-NSCP-ORIGINAL-OPERATION=X-NSCP-WCAP-PROPERTY-";
-    if (!dateTime || !dateTime.isValid || (dateTime.timezone == "floating")) {
+    if (!dateTime || !dateTime.isValid || dateTime.timezone.isUTC || dateTime.timezone.isFloating) {
         params += "DELETE^";
     } else {
-        params += ("REPLACE^" + encodeURIComponent(this.getAlignedTimezone(dateTime.timezone)));
+        params += ("REPLACE^" + encodeURIComponent(this.getAlignedTzid(dateTime.timezone)));
     }
     return params;
 };
@@ -277,7 +277,7 @@ function equalDatetimes(one, two) {
 function identicalDatetimes(one, two) {
     return ((!one && !two) ||
             (equalDatetimes(one, two) &&
-             (one.timezone == two.timezone)));
+             compareObjects(one.timezone, two.timezone)));
 }
 
 // @return null if nothing has changed else value to be written
@@ -564,11 +564,13 @@ function calWcapCalendar_storeItem(bAddItem, item, oldItem, request, netRespFunc
     else {
         var someDate = (item.startDate || item.entryDate || item.dueDate);
         if (someDate) {
-            // provide some date: eMail notification dates are influenced by this parameter...
-            params += ("&tzid=" + encodeURIComponent(
-                           this.getAlignedTimezone(someDate.timezone)));
+            someTz = someDate.timezone;
+            if (!someTz.isUTC && !someTz.isFloating) {
+                // provide some tzid: eMail notification dates are influenced by this parameter
+                params += ("&tzid=" + encodeURIComponent(this.getAlignedTzid(someTz)));
+            }
         }
-        
+
         if (item.id)
             params += ("&uid=" + encodeURIComponent(item.id));
         
@@ -836,11 +838,15 @@ calWcapCalendar.prototype.parseItems = function calWcapCalendar_parseItems(
                         log(attr + " is " + dt, this_);
                     }
                     var tzid = subComp.getFirstProperty(xprop);
-                    if (tzid != null) {
-                        subComp[attr] = dt.getInTimezone(tzid.value);
-                        if (LOG_LEVEL > 2) {
-                            log("patching " + xprop + ": from " +
-                                dt + " to " + subComp[attr], this_);
+                    if (tzid) {
+                        var tz = this_.session.getTimezone(tzid.value);
+                        ASSERT(tz, "timezone not found: " + tzid);
+                        if (tz) {
+                            subComp[attr] = dt.getInTimezone(tz);
+                            if (LOG_LEVEL > 2) {
+                                log("patching " + xprop + ": from " +
+                                    dt + " to " + subComp[attr], this_);
+                            }
                         }
                     }
                 }
diff --git a/calendar/providers/wcap/calWcapRequest.js b/calendar/providers/wcap/calWcapRequest.js
index 930cf5772f1..f75709f2e9c 100644
--- a/calendar/providers/wcap/calWcapRequest.js
+++ b/calendar/providers/wcap/calWcapRequest.js
@@ -409,7 +409,7 @@ function getWcapRequestStatusString(xml)
     return str;
 }
 
-function stringToIcal(data, expectedErrno)
+function stringToIcal(session, data, expectedErrno)
 {
     if (!data || data.length == 0) { // assuming time-out; WTF.
         throw new Components.Exception(
@@ -418,7 +418,7 @@ function stringToIcal(data, expectedErrno)
     }
     var icalRootComp;
     try {
-        icalRootComp = getIcsService().parseICS(data);
+        icalRootComp = getIcsService().parseICS(data, session /*implements calITimezoneProvider*/);
     }
     catch (exc) { // map into more useful error string:
         throw new Components.Exception("error parsing ical data!",
@@ -428,7 +428,7 @@ function stringToIcal(data, expectedErrno)
     return icalRootComp;
 }
 
-function stringToXml(data, expectedErrno)
+function stringToXml(session, data, expectedErrno)
 {
     if (!data || data.length == 0) { // assuming time-out
         throw new Components.Exception(
diff --git a/calendar/providers/wcap/calWcapSession.js b/calendar/providers/wcap/calWcapSession.js
index 8211a77ff00..76b107c153b 100644
--- a/calendar/providers/wcap/calWcapSession.js
+++ b/calendar/providers/wcap/calWcapSession.js
@@ -54,6 +54,25 @@ function getWcapSessionFor(cal, uri) {
     return session;
 }
 
+function calWcapTimezone(tzProvider, tzid_, component_) {
+    this.wrappedJSObject = this;
+    this.provider = tzProvider;
+    this.component = component_;
+    this.tzid = tzid_;
+    this.isUTC = false;
+    this.isFloating = false;
+    this.latitude = "";
+    this.longitude = "";
+}
+calWcapTimezone.prototype = {
+    toString: function() {
+        // xxx todo remove: for some time, we want to know if a calITimezone object
+        //                  is handled as string...
+        ASSERT(false, "calWcapTimezone.toString!");
+        return this.component.toString();
+    }
+};
+
 function calWcapSession(contextId, thatUri) {
     this.wrappedJSObject = this;
     this.m_contextId = contextId;
@@ -78,6 +97,7 @@ calWcapSession.prototype = {
     m_ifaces: [ calIWcapSession,
                 calIFreeBusyProvider,
                 calICalendarSearchProvider,
+                Components.interfaces.calITimezoneProvider,
                 Components.interfaces.calICalendarManagerObserver,
                 Components.interfaces.nsIInterfaceRequestor,
                 Components.interfaces.nsIClassInfo,
@@ -145,18 +165,44 @@ calWcapSession.prototype = {
         }
     },
 
+    // calITimezoneProvider:
     m_serverTimezones: null,
-    isSupportedTimezone: function calWcapSession_isSupportedTimezone(tzid)
-    {
-        if (!this.m_serverTimezones) {
-            throw new Components.Exception(
-                "early run into getSupportedTimezones()!",
-                Components.results.NS_ERROR_NOT_AVAILABLE);
+    get timezoneIds() {
+        var tzids = [];
+        tzids.push("floating");
+        tzids.push("UTC");
+        for (var tz in this.m_serverTimezones) {
+            tzids.push(tz.tzid);
         }
-        return this.m_serverTimezones.some(
-            function someFunc(id) { return tzid == id; } );
+        return {
+            // nsIUTF8StringEnumerator:
+            m_index: 0,
+            getNext: function() {
+                if (this.m_index >= tzids) {
+                    ASSERT(false, "calWcapSession::timezoneIds enumerator!");
+                    throw Components.results.NS_ERROR_UNEXPECTED;
+                }
+                return tzids[this.m_index++];
+            },
+            hasMoreElements: function() {
+                return (this.m_index < tzids);
+            }
+        };
     },
-    
+    getTimezone: function calWcapSession_getTimezone(tzid) {
+        switch (tzid) {
+        case "floating":
+            return floating();
+        case "UTC":
+            return UTC();
+        default:
+            if (this.m_serverTimezones) {
+                return this.m_serverTimezones[tzid];
+            }
+            return null;
+        }
+    },
+
     m_serverTimeDiff: null,
     getServerTime: function calWcapSession_getServerTime(localTime)
     {
@@ -374,7 +420,7 @@ calWcapSession.prototype = {
                     // currently, xml parsing at an early stage during
                     // process startup does not work reliably, so use
                     // libical parsing for now:
-                    var icalRootComp = stringToIcal(str);
+                    var icalRootComp = stringToIcal(this_, str);
                     var prop = icalRootComp.getFirstProperty("X-NSCP-WCAP-SESSION-ID");
                     if (!prop) {
                         throw new Components.Exception(
@@ -438,7 +484,7 @@ calWcapSession.prototype = {
                 function netResp(err, str) {
                     if (err)
                         throw err;
-                    stringToXml(str, -1 /* logout successfull */);
+                    stringToXml(this_, str, -1 /* logout successfull */);
                 }, url);
         }
         else {
@@ -460,7 +506,7 @@ calWcapSession.prototype = {
                     var icalRootComp;
                     if (!err) {
                         try {
-                            icalRootComp = stringToIcal(str);
+                            icalRootComp = stringToIcal(this_, str);
                         }
                         catch (exc) {
                             err = exc;
@@ -726,7 +772,7 @@ calWcapSession.prototype = {
     installServerTimezones:
     function calWcapSession_installServerTimezones(sessionId, request)
     {
-        this.m_serverTimezones = [];
+        this.m_serverTimezones = {};
         var this_ = this;
         this_.issueNetworkRequest_(
             request,
@@ -734,17 +780,12 @@ calWcapSession.prototype = {
                 if (err)
                     throw err;
                 var tzids = [];
-                var icsService = getIcsService();
                 forEachIcalComponent(
                     data, "VTIMEZONE",
                     function eachComp(subComp) {
                         try {
-                            var tzCal = icsService.createIcalComponent("VCALENDAR");
-                            subComp = subComp.clone();
-                            tzCal.addSubcomponent(subComp);
-                            icsService.addTimezone(tzCal, "", "");
-                            this_.m_serverTimezones.push(
-                                subComp.getFirstProperty("TZID").value);
+                            var tzid = subComp.getFirstProperty("TZID").value;
+                            this_.m_serverTimezones[tzid] = new calWcapTimezone(this_, tzid, subComp);
                         }
                         catch (exc) { // ignore but errors:
                             logError(exc, this_);
@@ -798,6 +839,7 @@ calWcapSession.prototype = {
         request, respFunc, dataConvFunc, wcapCommand, params, sessionId)
     {
         var url = this.getCommandUrl(wcapCommand, params, sessionId);
+        var this_ = this;
         issueNetworkRequest(
             request,
             function netResp(err, str) {
@@ -805,7 +847,7 @@ calWcapSession.prototype = {
                 if (!err) {
                     try {
                         if (dataConvFunc)
-                            data = dataConvFunc(str);
+                            data = dataConvFunc(this_, str);
                         else
                             data = str;
                     }
@@ -1040,13 +1082,13 @@ calWcapSession.prototype = {
 
             // cannot use stringToXml here, because cs 6.3 returns plain nothing
             // on invalid user freebusy requests. WTF.
-            function stringToXml_(data) {
+            function stringToXml_(session, data) {
                 if (!data || data.length == 0) { // assuming invalid user
                     throw new Components.Exception(
                         wcapErrorToString(calIWcapErrors.WCAP_CALENDAR_DOES_NOT_EXIST),
                         calIWcapErrors.WCAP_CALENDAR_DOES_NOT_EXIST);
                 }
-                return stringToXml(data);
+                return stringToXml(session, data);
             }
             this.issueNetworkRequest(
                 request,
diff --git a/calendar/providers/wcap/calWcapUtils.js b/calendar/providers/wcap/calWcapUtils.js
index bcf10f61014..f7f61b04f77 100644
--- a/calendar/providers/wcap/calWcapUtils.js
+++ b/calendar/providers/wcap/calWcapUtils.js
@@ -43,8 +43,7 @@ var g_logPrefObserver = null;
 
 function initLogging()
 {
-    g_logTimezone = getPref("calendar.timezone.local", null);
-    
+    g_logTimezone = calendarDefaultTimezone();
     if (g_logFilestream) {
         try {
             g_logFilestream.close();
@@ -306,10 +305,10 @@ function getIcalUTC(dt) {
         return "0";
     else {
         var dtz = dt.timezone;
-        if (dtz == "UTC" || dtz == "floating")
+        if (dtz.isUTC || dtz.isFloating)
             return dt.icalString;
         else
-            return dt.getInTimezone("UTC").icalString;
+            return dt.getInTimezone(UTC()).icalString;
     }
 }
 
diff --git a/calendar/resources/content/calendarWindow.js b/calendar/resources/content/calendarWindow.js
index 517801bb074..b2a0ef85434 100644
--- a/calendar/resources/content/calendarWindow.js
+++ b/calendar/resources/content/calendarWindow.js
@@ -87,7 +87,7 @@ function CalendarWindow( )
 CalendarWindow.prototype.pickAndGoToDate = function calWin_pickAndGoToDate( )
 {
   var args = new Object();
-  args.initialDate = currentView().selectedDay.getInTimezone("floating").jsDate;
+  args.initialDate = currentView().selectedDay.getInTimezone(floating()).jsDate;
   args.onOk = function receiveAndGoToDate( pickedDate ) {
     currentView().goToDay( jsDateToDateTime(pickedDate) );
     document.getElementById( "lefthandcalendar" ).value = pickedDate;
diff --git a/calendar/resources/content/clipboard.js b/calendar/resources/content/clipboard.js
index 8ea28162fb4..65c58c640bc 100644
--- a/calendar/resources/content/clipboard.js
+++ b/calendar/resources/content/clipboard.js
@@ -216,7 +216,7 @@ function pasteFromClipboard()
         case "text/unicode":
             var icssrv = Components.classes["@mozilla.org/calendar/ics-service;1"]
                                    .getService(Components.interfaces.calIICSService);
-            var calComp = icssrv.parseICS(data);
+            var calComp = icssrv.parseICS(data, null);
             var subComp = calComp.getFirstSubcomponent("ANY");
             while (subComp) {
                 switch (subComp.componentType) {
diff --git a/calendar/test/homegrown/ics2ics.js b/calendar/test/homegrown/ics2ics.js
index 964d3d223c3..bf8995d9f8d 100644
--- a/calendar/test/homegrown/ics2ics.js
+++ b/calendar/test/homegrown/ics2ics.js
@@ -15,7 +15,7 @@ var str = "BEGIN:VCALENDAR\n";
 var icsServ = Components.classes["@mozilla.org/calendar/ics-service;1"]
                         .getService(Components.interfaces.calIICSService);
 
-var calComp = icsServ.parseICS(str);
+var calComp = icsServ.parseICS(str, null);
 var subComp = calComp.getFirstSubcomponent("VEVENT");
 var event = Components.classes["@mozilla.org/calendar/event;1"]
                       .createInstance(Components.interfaces.calIEvent);
diff --git a/calendar/test/unit/head_consts.js b/calendar/test/unit/head_consts.js
index ee600cf5e47..b1de3b5add8 100644
--- a/calendar/test/unit/head_consts.js
+++ b/calendar/test/unit/head_consts.js
@@ -19,6 +19,7 @@
  * the Initial Developer. All Rights Reserved.
  *
  * Contributor(s):
+ *   Daniel Boelzle <daniel.boelzle@sun.com>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either the GNU General Public License Version 2 or later (the "GPL"), or
@@ -37,10 +38,35 @@
 const Cc = Components.classes;
 const Ci = Components.interfaces;
 
+/* Shortcut to the timezone service */
+function getTimezoneService() {
+    if (getTimezoneService.mObject === undefined) {
+        getTimezoneService.mObject = Components.classes["@mozilla.org/calendar/timezone-service;1"]
+                                               .getService(Components.interfaces.calITimezoneService);
+    }
+    return getTimezoneService.mObject;
+}
+
+/// @return the UTC timezone.
+function UTC() {
+    if (UTC.mObject === undefined) {
+        UTC.mObject = getTimezoneService().UTC;
+    }
+    return UTC.mObject;
+}
+
+/// @return the floating timezone.
+function floating() {
+    if (floating.mObject === undefined) {
+        floating.mObject = getTimezoneService().floating;
+    }
+    return floating.mObject;
+}
+
 function createDate(aYear, aMonth, aDay) {
     var cd = Cc["@mozilla.org/calendar/datetime;1"].
              createInstance(Ci.calIDateTime);
-    cd.resetTo(aYear, aMonth, aDay, 0, 0, 0, "UTC");
+    cd.resetTo(aYear, aMonth, aDay, 0, 0, 0, UTC());
     cd.isDate = true;
     return cd;
 }
diff --git a/calendar/test/unit/test_datetime.js b/calendar/test/unit/test_datetime.js
index 5703cedc99a..746ac37cfd9 100644
--- a/calendar/test/unit/test_datetime.js
+++ b/calendar/test/unit/test_datetime.js
@@ -35,22 +35,23 @@
  * ***** END LICENSE BLOCK ***** */
 
 function run_test() {
-    const Cc = Components.classes;
-    const Ci = Components.interfaces;
+    function getMozTimezone(tzid) {
+        return getTimezoneService().getTimezone(tzid);
+    }
 
     var cd = Cc["@mozilla.org/calendar/datetime;1"].
              createInstance(Ci.calIDateTime);
     cd.resetTo(2005, 10, 13,
                10, 0, 0,
-               "/mozilla.org/20050126_1/America/Bogota");
+               getMozTimezone("/mozilla.org/20050126_1/America/Bogota"));
 
     do_check_eq(cd.hour, 10);
     do_check_eq(cd.icalString, "20051113T100000");
 
-    var cd_floating = cd.getInTimezone("floating");
+    var cd_floating = cd.getInTimezone(floating());
     do_check_eq(cd_floating.hour, 10);
 
-    var cd_utc = cd.getInTimezone("UTC");
+    var cd_utc = cd.getInTimezone(UTC());
     do_check_eq(cd_utc.hour, 15);
     do_check_eq(cd_utc.icalString, "20051113T150000Z");
 
@@ -70,7 +71,7 @@ function run_test() {
     // Daylight savings test
     cd.resetTo(2006, 2, 26,
                1, 0, 0,
-               "/mozilla.org/20050126_1/Europe/Amsterdam");
+               getMozTimezone("/mozilla.org/20050126_1/Europe/Amsterdam"));
 
     do_check_eq(cd.weekday, 0);
     do_check_eq(cd.timezoneOffset, 1*3600);
@@ -81,24 +82,24 @@ function run_test() {
     // Bug 398724 – Problems with floating all-day items
     var event = Cc["@mozilla.org/calendar/event;1"].createInstance(Ci.calIEvent);
     event.icalString = "BEGIN:VEVENT\nUID:45674d53-229f-48c6-9f3b-f2b601e7ae4d\nSUMMARY:New Event\nDTSTART;VALUE=DATE:20071003\nDTEND;VALUE=DATE:20071004\nEND:VEVENT";
-    do_check_eq(event.startDate.timezone, "floating");
-    do_check_eq(event.endDate.timezone, "floating");
+    do_check_eq(event.startDate.timezone.isFloating, true);
+    do_check_eq(event.endDate.timezone.isFloating, true);
 
     // Bug 392853 - Same times, different timezones, but subtractDate says times are PT0S apart
     const zeroLength = Cc["@mozilla.org/calendar/duration;1"].createInstance(Ci.calIDuration);
     const a = Cc["@mozilla.org/calendar/datetime;1"].createInstance(Ci.calIDateTime);
     a.jsDate = new Date();
-    a.timezone = "/mozilla.org/20070129_1/Europe/Berlin";
+    a.timezone = getMozTimezone("/mozilla.org/20070129_1/Europe/Berlin");
 
     var b = a.clone();
-    b.timezone = "/mozilla.org/20070129_1/America/New_York";
+    b.timezone = getMozTimezone("/mozilla.org/20070129_1/America/New_York");
 
     var duration = a.subtractDate(b);
     do_check_neq(duration.compare(zeroLength), 0);
     do_check_neq(a.compare(b), 0);
 
     // Should lead to zero length duration
-    b = a.getInTimezone("/mozilla.org/20070129_1/America/New_York");
+    b = a.getInTimezone(getMozTimezone("/mozilla.org/20070129_1/America/New_York"));
     duration = a.subtractDate(b);
     do_check_eq(duration.compare(zeroLength), 0);
     do_check_eq(a.compare(b), 0);