pjs/netwerk/base/public/nsICachingChannel.idl

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/* -*- 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
*
* 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 mozilla.org code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 2001
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Darin Fisher <darin@netscape.com> (original author)
*
* 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 nsIFile;
/**
* A channel may optionally implement this interface to allow clients
* to affect its behavior with respect to how it uses the cache service.
*
* This interface provides:
* 1) Support for "stream as file" semantics (for JAR and plugins).
* 2) Support for "pinning" cached data in the cache (for printing and save-as).
* 3) Support for uniquely identifying cached data in cases when the URL
* is insufficient (e.g., HTTP form submission).
*/
[scriptable, uuid(855bcc4d-0987-45b6-b138-3bf0bf407703)]
interface nsICachingChannel : nsISupports
{
/**
* Set/get the cache token... uniquely identifies the data in the cache.
* Holding a reference to this token prevents the cached data from being
* removed.
*
* A cache token retrieved from a particular instance of nsICachingChannel
* could be set on another instance of nsICachingChannel provided the
* underlying implementations are compatible. The implementation of
* nsICachingChannel would be expected to only read from the cache entry
* identified by the cache token and not try to validate it.
*
* The cache token can be QI'd to a nsICacheEntryInfo if more detail
* about the cache entry is needed (e.g., expiration time).
*/
attribute nsISupports cacheToken;
/**
* Set/get the cache key... uniquely identifies the data in the cache
* for this channel. Holding a reference to this key does NOT prevent
* the cached data from being removed.
*
* A cache key retrieved from a particular instance of nsICachingChannel
* could be set on another instance of nsICachingChannel provided the
* underlying implementations are compatible and provided the new
* channel instance was created with the same URI. The implementation of
* nsICachingChannel would be expected to use the cache entry identified
* by the cache token. Depending on the value of nsIRequest::loadFlags,
* the cache entry may be validated, overwritten, or simply read.
*
* The cache key may be NULL indicating that the URI of the channel is
* sufficient to locate the same cache entry. Setting a NULL cache key
* is likewise valid.
*/
attribute nsISupports cacheKey;
/**
* Specifies whether or not the data should be cached to a file. This
* may fail if the disk cache is not present. The value of this attribute
* is usually only settable during the processing of a channel's
* OnStartRequest. The default value of this attribute depends on the
* particular implementation of nsICachingChannel.
*/
attribute boolean cacheAsFile;
/**
* Specifies whether or not the data should be placed in the offline cache,
* in addition to normal memory/disk caching. This may fail if the offline
* cache is not present. The value of this attribute should be set before
* opening the channel.
*/
attribute boolean cacheForOfflineUse;
/**
* Get the "file" where the cached data can be found. This is valid for
* as long as a reference to the cache token is held. This may return
* an error if cacheAsFile is false.
*/
readonly attribute nsIFile cacheFile;
/**
* TRUE if this channel's data is being loaded from the cache. This value
* is undefined before the channel fires its OnStartRequest notification
* and after the channel fires its OnStopRequest notification.
*/
boolean isFromCache();
/**************************************************************************
* Caching channel specific load flags:
*/
/**
* This load flag causes the local cache to be skipped when fetching a
* request. Unlike LOAD_BYPASS_CACHE, it does not force an end-to-end load
* (i.e., it does not affect proxy caches).
*/
const unsigned long LOAD_BYPASS_LOCAL_CACHE = 1 << 28;
/**
* This load flag causes the local cache to be skipped if the request
* would otherwise block waiting to access the cache.
*/
const unsigned long LOAD_BYPASS_LOCAL_CACHE_IF_BUSY = 1 << 29;
/**
* This load flag inhibits fetching from the net if the data in the cache
* has been evicted. An error of NS_ERROR_DOCUMENT_NOT_CACHED will be sent
* to the listener's onStopRequest in this case.
*/
const unsigned long LOAD_ONLY_FROM_CACHE = 1 << 30;
/**
* This load flag controls what happens when a document would be loaded
* from the cache to satisfy a call to AsyncOpen. If this attribute is
* set to TRUE, then the document will not be loaded from the cache. A
* stream listener can check nsICachingChannel::isFromCache to determine
* if the AsyncOpen will actually result in data being streamed.
*
* If this flag has been set, and the request can be satisfied via the
* cache, then the OnDataAvailable events will be skipped. The listener
* will only see OnStartRequest followed by OnStopRequest.
*/
const unsigned long LOAD_ONLY_IF_MODIFIED = 1 << 31;
};