gecko/netwerk/base/public/nsIChannel.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
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*
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* 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
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* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
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#include "nsIRequest.idl"
interface nsIURI;
interface nsIInterfaceRequestor;
interface nsIInputStream;
interface nsIStreamListener;
/**
* The nsIChannel interface allows clients to construct "GET" requests for
* specific protocols, and manage them in a uniform way. Once a channel is
* created (via nsIIOService::newChannel), parameters for that request may
* be set by using the channel attributes, or by QI'ing to a subclass of
* nsIChannel for protocol-specific parameters. Then, the URI can be fetched
* by calling nsIChannel::open or nsIChannel::asyncOpen.
*
* After a request has been completed, the channel is still valid for accessing
* protocol-specific results. For example, QI'ing to nsIHttpChannel allows
* response headers to be retrieved for the corresponding http transaction.
*
* @status FROZEN
*/
[scriptable, uuid(c63a055a-a676-4e71-bf3c-6cfa11082018)]
interface nsIChannel : nsIRequest
{
/**
* The original URI used to construct the channel. This is used in
* the case of a redirect or URI "resolution" (e.g. resolving a
* resource: URI to a file: URI) so that the original pre-redirect
* URI can still be obtained. This is never null. Attempts to
* set it to null must throw.
*
* NOTE: this is distinctly different from the http Referer (referring URI),
* which is typically the page that contained the original URI (accessible
* from nsIHttpChannel).
*/
attribute nsIURI originalURI;
/**
* The URI corresponding to the channel. Its value is immutable.
*/
readonly attribute nsIURI URI;
/**
* The owner, corresponding to the entity that is responsible for this
* channel. Used by the security manager to grant or deny privileges to
* mobile code loaded from this channel.
*
* NOTE: this is a strong reference to the owner, so if the owner is also
* holding a strong reference to the channel, care must be taken to
* explicitly drop its reference to the channel.
*/
attribute nsISupports owner;
/**
* The notification callbacks for the channel. This is set by clients, who
* wish to provide a means to receive progress, status and protocol-specific
* notifications. If this value is NULL, the channel implementation may use
* the notification callbacks from its load group. The channel may also
* query the notification callbacks from its load group if its notification
* callbacks do not supply the requested interface.
*
* Interfaces commonly requested include: nsIProgressEventSink, nsIPrompt,
* and nsIAuthPrompt/nsIAuthPrompt2.
*
* When the channel is done, it must not continue holding references to
* this object.
*
* NOTE: A channel implementation should take care when "caching" an
* interface pointer queried from its notification callbacks. If the
* notification callbacks are changed, then a cached interface pointer may
* become invalid and may therefore need to be re-queried.
*/
attribute nsIInterfaceRequestor notificationCallbacks;
/**
* Transport-level security information (if any) corresponding to the channel.
*/
readonly attribute nsISupports securityInfo;
/**
* The MIME type of the channel's content if available.
*
* NOTE: the content type can often be wrongly specified (e.g., wrong file
* extension, wrong MIME type, wrong document type stored on a server, etc.),
* and the caller most likely wants to verify with the actual data.
*
* Setting contentType before the channel has been opened provides a hint
* to the channel as to what the MIME type is. The channel may ignore this
* hint in deciding on the actual MIME type that it will report.
*
* Setting contentType after onStartRequest has been fired or after open()
* is called will override the type determined by the channel.
*
* Setting contentType between the time that asyncOpen() is called and the
* time when onStartRequest is fired has undefined behavior at this time.
*
* The value of the contentType attribute is a lowercase string. A value
* assigned to this attribute will be parsed and normalized as follows:
* 1- any parameters (delimited with a ';') will be stripped.
* 2- if a charset parameter is given, then its value will replace the
* the contentCharset attribute of the channel.
* 3- the stripped contentType will be lowercased.
* Any implementation of nsIChannel must follow these rules.
*/
attribute ACString contentType;
/**
* The character set of the channel's content if available and if applicable.
* This attribute only applies to textual data.
*
* The value of the contentCharset attribute is a mixedcase string.
*/
attribute ACString contentCharset;
/**
* The length of the data associated with the channel if available. A value
* of -1 indicates that the content length is unknown.
*
* Callers should prefer getting the "content-length" property
* as 64-bit value by QIing the channel to nsIPropertyBag2,
* if that interface is exposed by the channel.
*/
attribute long contentLength;
/**
* Synchronously open the channel.
*
* @return blocking input stream to the channel's data.
*
* NOTE: nsIChannel implementations are not required to implement this
* method. Moreover, since this method may block the calling thread, it
* should not be called on a thread that processes UI events.
*
* NOTE: Implementations should throw NS_ERROR_IN_PROGRESS if the channel
* is reopened.
*/
nsIInputStream open();
/**
* Asynchronously open this channel. Data is fed to the specified stream
* listener as it becomes available. The stream listener's methods are
* called on the thread that calls asyncOpen and are not called until
* after asyncOpen returns. If asyncOpen returns successfully, the
* channel promises to call at least onStartRequest and onStopRequest.
*
* If the nsIRequest object passed to the stream listener's methods is not
* this channel, an appropriate onChannelRedirect notification needs to be
* sent to the notification callbacks before onStartRequest is called.
* Once onStartRequest is called, all following method calls on aListener
* will get the request that was passed to onStartRequest.
*
* If the channel's and loadgroup's notification callbacks do not provide
* an nsIChannelEventSink when onChannelRedirect would be called, that's
* equivalent to having called onChannelRedirect.
*
* If asyncOpen returns successfully, the channel is responsible for
* keeping itself alive until it has called onStopRequest on aListener or
* called onChannelRedirect.
*
* Implementations are allowed to synchronously add themselves to the
* associated load group (if any).
*
* NOTE: Implementations should throw NS_ERROR_ALREADY_OPENED if the
* channel is reopened.
*
* @param aListener the nsIStreamListener implementation
* @param aContext an opaque parameter forwarded to aListener's methods
* @see nsIChannelEventSink for onChannelRedirect
*/
void asyncOpen(in nsIStreamListener aListener, in nsISupports aContext);
/**************************************************************************
* Channel specific load flags:
*
* Bits 22-31 are reserved for future use by this interface or one of its
* derivatives (e.g., see nsICachingChannel).
*/
/**
* Set (e.g., by the docshell) to indicate whether or not the channel
* corresponds to a document URI.
*/
const unsigned long LOAD_DOCUMENT_URI = 1 << 16;
/**
* If the end consumer for this load has been retargeted after discovering
* its content, this flag will be set:
*/
const unsigned long LOAD_RETARGETED_DOCUMENT_URI = 1 << 17;
/**
* This flag is set to indicate that this channel is replacing another
* channel. This means that:
*
* 1) the stream listener this channel will be notifying was initially
* passed to the asyncOpen method of some other channel
*
* and
*
* 2) this channel's URI is a better identifier of the resource being
* accessed than this channel's originalURI.
*
* This flag can be set, for example, for redirects or for cases when a
* single channel has multiple parts to it (and thus can follow
* onStopRequest with another onStartRequest/onStopRequest pair, each pair
* for a different request).
*/
const unsigned long LOAD_REPLACE = 1 << 18;
/**
* Set (e.g., by the docshell) to indicate whether or not the channel
* corresponds to an initial document URI load (e.g., link click).
*/
const unsigned long LOAD_INITIAL_DOCUMENT_URI = 1 << 19;
/**
* Set (e.g., by the URILoader) to indicate whether or not the end consumer
* for this load has been determined.
*/
const unsigned long LOAD_TARGETED = 1 << 20;
/**
* If this flag is set, the channel should call the content sniffers as
* described in nsNetCID.h about NS_CONTENT_SNIFFER_CATEGORY.
*
* Note: Channels may ignore this flag; however, new channel implementations
* should only do so with good reason.
*/
const unsigned long LOAD_CALL_CONTENT_SNIFFERS = 1 << 21;
};