pjs/netwerk/cache/public/nsICachedNetData.idl

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* The contents of this file are subject to the Netscape 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/NPL/
*
* 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 Netscape are
* Copyright (C) 1998 Netscape Communications Corporation. All
* Rights Reserved.
*
* Contributor(s):
*/
#include "nsrootidl.idl"
#include "nsISupports.idl"
interface nsIURI;
interface nsIObserver;
interface nsIChannel;
interface nsINetDataCache;
interface nsINetDataCacheRecord;
interface nsILoadGroup;
interface nsIStreamListener;
/**
* The nsICachedNetData interface represents a single entry in a database that
* caches data retrieved from the network. This interface is implemented by the
* cache manager on top of the low-level nsINetDataCacheRecord and
* nsINetDataCache interfaces that are implemented by the database.
*
* Each cache record may contain both content and metadata. The content may
* be, for example, GIF image data or HTML, and it is accessed through
* nsIChannel's streaming API. The opaque metadata, which may contain HTTP
* headers among other things, is stored as a byte array. Each entry in the
* cache is indexed by two different keys: a record id number and a key created
* by combining the URI with a "secondary key", e.g. HTTP post data.
*
* @See nsINetDataCacheRecord
* @See nsINetDataCache
* @See nsINetDataDiskCache
* @See nsINetDataCacheManager
*/
[scriptable, uuid(6aeb2a40-6d43-11d3-90c8-000064657374)]
interface nsICachedNetData : nsISupports
{
/**
* String form of the URI provided as an argument to the call to
* nsINetDataCacheManager::GetCachedNetData() that created this record.
*/
readonly attribute string uriSpec;
/**
* Getter for the opaque secondary database key provided as an argument to
* the call to nsINetDataCacheManager::GetCachedNetData() that created this
* record.
*/
void getSecondaryKey(out unsigned long length,
[retval, size_is(length)] out string secondaryKey);
/**
* This flag may be set by a protocol handler to indicate that it supports
* partial fetching of data. In that case, the cache manager is permitted
* to truncate the entry's content to accommodate incoming data for other
* cache entries rather than deleting it wholesale.
*/
attribute boolean allowPartial;
/**
* This flag indicates that the write stream supplying content data for the
* cache did not complete normally and, therefore, the content may be
* truncated.
*/
readonly attribute boolean partialFlag;
/**
* This flag can be set and cleared by a protocol handler as a form of
* self-notification, so as to avoid race conditions in which a protocol
* handler issues two identical network requests to fill the same cache
* entry. The cache manager itself largely ignores this flag.
*/
attribute boolean updateInProgress;
/**
* inUse is set if any existing channels are associated with this cache
* entry or if the updateInProgess flag is set. This can be used to
* prevent writing to a cache entry by a protocol handler if it's being
* read or written elsewhere.
*/
readonly attribute boolean inUse;
/**
* Date/time that the document was last stored on the origin server, as
* supplied by the protocol handler. This value is used as input to the
* cache replacement policy, i.e. it is not used for validation. If the
* protocol can't supply a last-modified time, this attribute should remain
* unset. When unset, the value of this attribute is zero.
*
* FIXME: Should use nsIDateTime interface, once it's created
* instead of PRTime, for improved scriptability ?
*/
attribute PRTime lastModifiedTime;
/**
* Supplied by the protocol handler, the expirationTime attribute specifies
* the time until which the document is guaranteed fresh, i.e. the document
* does not have to be validated with the server and, therefore, any data
* in cache is definitely usable. The value of this attribute serves as a
* hint to the cache replacement policy. Only one of either staleTime or
* expirationTime may be set for a single cache record. When unset, the
* value of this attribute is zero.
*/
attribute PRTime expirationTime;
/**
* Date/time supplied by the protocol handler, at which point the content
* is *likely* to be stale, i.e. the data in the cache may be out-of-date
* with respect to the data on the server. This heuristic date does not
* necessarily correspond to the HTTP Expires header, as it does not
* determine when cached network data must be validated with the origin
* server, but only serves as a hint to the cache replacement policy. Only
* one of either staleTime or expirationTime may be set for a single cache
* record. When unset, the value of this attribute is zero.
*/
attribute PRTime staleTime;
/**
* Date/time of last access of the data in this cache record, as determined
* by the cache manager.
*/
readonly attribute PRTime lastAccessTime;
readonly attribute PRTime lastUpdateTime;
/**
* Number of times this record has been accessed since it was first stored.
*/
readonly attribute PRUint16 numberAccesses;
/**
* Accessor methods for opaque meta-data which can be read and updated
* independently of the content data.
*
* The aTag argument can be used to accommodate multiple clients of the
* cache API, each of which wants to store its own private meta-data into
* the cache. For example, there could be a "headers" tag that the HTTP
* protocol handler uses to store http response headers and a "image size"
* tag used to store the image dimensions of a GIF file. The aData
* argument refers to an opaque blob of arbitrary bytes.
*
* IMPORTANT: If aData does not contain byte-oriented data, i.e. it's not a
* string, the contents of aData must be byte-swapped by the,
* caller, so as to make the cache files endian-independent.
*/
void getAnnotation(in string aTag,
out PRUint32 aLength, [size_is(aLength), retval] out string aData);
void setAnnotation(in string aTag,
in PRUint32 aLength, [size_is(aLength)] in string aData);
/**
* As a getter, return the number of content bytes stored in the cache,
* i.e. via the nsIChannel streaming APIs. This may be less than the
* complete content length if a partial cache fill occurred. The cached
* content can be truncated by setting the value of this attribute. The
* value of the attribute represents a logical, not a physical, length. If
* compression has been used, the content may consume less storage than
* indicated by this attribute.
*
* When this attribute is set to zero the associated cache disk file, if
* any, should be deleted.
*/
attribute PRUint32 storedContentLength;
/**
* Length of stored content, which may be less than storage consumed if
* compression is used
*/
readonly attribute PRUint32 logicalLength;
/**
* Opaque security info associated with the cache entry; it can't be serialized
* to disk, so it'll only make sense with memory cache
*/
attribute nsISupports securityInfo;
/**
* Notify any observers associated with this cache entry of the deletion
* request. If all observers drop their reference to the cache entry,
* proceed to delete the underlying cache database record and associated
* content storage.
*/
void delete();
/**
* Flush any changes in this entry's data to the cache database. This
* method will automatically be called when the last reference to the cache
* is dropped, but it can also be called explicitly for a synchronous
* effect.
*/
void commit();
/**
* Parent container cache for this entry.
*/
readonly attribute nsINetDataCache cache;
/**
* Create a channel for reading or writing a stream of content into the
* entry. It is expected that many of the nsIChannel methods return
* NS_NOT_IMPLEMENTED, including:
*
* + GetURI()
* + GetContentType()
* + GetContentLength()
*
* Though nsIChannel provides for both async and synchronous I/O APIs, both
* may not be implemented. Only AsyncRead() and OpenOutputStream() is
* required.
*/
nsIChannel newChannel(in nsILoadGroup aLoadGroup);
/**
* This method can be used by a caching protocol handler to store data in
* the cache by forking an asynchronous read stream so that it is
* simultaneously sent to a requester and written into the cache. This
* method implicitly sets the updateInProgress flag, if it has not already
* been set.
*/
nsIStreamListener interceptAsyncRead(in nsIStreamListener aOriginalListener,
in PRUint32 aStartOffset);
};