michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
michael@0: /* vim:set ts=4 sw=4 sts=4 cin: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "nsISupports.idl"
michael@0: 
michael@0: interface nsIChannel;
michael@0: interface nsIAsyncVerifyRedirectCallback;
michael@0: 
michael@0: /**
michael@0:  * Implement this interface to receive control over various channel events.
michael@0:  * Channels will try to get this interface from a channel's
michael@0:  * notificationCallbacks or, if not available there, from the loadGroup's
michael@0:  * notificationCallbacks.
michael@0:  *
michael@0:  * These methods are called before onStartRequest.
michael@0:  */
michael@0: [scriptable, uuid(a430d870-df77-4502-9570-d46a8de33154)]
michael@0: interface nsIChannelEventSink : nsISupports
michael@0: {
michael@0:     /**
michael@0:      * This is a temporary redirect. New requests for this resource should
michael@0:      * continue to use the URI of the old channel.
michael@0:      *
michael@0:      * The new URI may be identical to the old one.
michael@0:      */
michael@0:     const unsigned long REDIRECT_TEMPORARY = 1 << 0;
michael@0: 
michael@0:     /**
michael@0:      * This is a permanent redirect. New requests for this resource should use
michael@0:      * the URI of the new channel (This might be an HTTP 301 reponse).
michael@0:      * If this flag is not set, this is a temporary redirect.
michael@0:      *
michael@0:      * The new URI may be identical to the old one.
michael@0:      */
michael@0:     const unsigned long REDIRECT_PERMANENT = 1 << 1;
michael@0: 
michael@0:     /**
michael@0:      * This is an internal redirect, i.e. it was not initiated by the remote
michael@0:      * server, but is specific to the channel implementation.
michael@0:      *
michael@0:      * The new URI may be identical to the old one.
michael@0:      */
michael@0:     const unsigned long REDIRECT_INTERNAL = 1 << 2;
michael@0: 
michael@0:     /**
michael@0:      * Called when a redirect occurs. This may happen due to an HTTP 3xx status
michael@0:      * code. The purpose of this method is to notify the sink that a redirect
michael@0:      * is about to happen, but also to give the sink the right to veto the
michael@0:      * redirect by throwing or passing a failure-code in the callback.
michael@0:      *
michael@0:      * Note that vetoing the redirect simply means that |newChannel| will not
michael@0:      * be opened. It is important to understand that |oldChannel| will continue
michael@0:      * loading as if it received a HTTP 200, which includes notifying observers
michael@0:      * and possibly display or process content attached to the HTTP response.
michael@0:      * If the sink wants to prevent this loading it must explicitly deal with
michael@0:      * it, e.g. by calling |oldChannel->Cancel()|
michael@0:      *
michael@0:      * There is a certain freedom in implementing this method:
michael@0:      *
michael@0:      * If the return-value indicates success, a callback on |callback| is
michael@0:      * required. This callback can be done from within asyncOnChannelRedirect
michael@0:      * (effectively making the call synchronous) or at some point later
michael@0:      * (making the call asynchronous). Repeat: A callback must be done
michael@0:      * if this method returns successfully.
michael@0:      *
michael@0:      * If the return value indicates error (method throws an exception)
michael@0:      * the redirect is vetoed and no callback must be done. Repeat: No
michael@0:      * callback must be done if this method throws!
michael@0:      *
michael@0:      * @see nsIAsyncVerifyRedirectCallback::onRedirectVerifyCallback()
michael@0:      *
michael@0:      * @param oldChannel
michael@0:      *        The channel that's being redirected.
michael@0:      * @param newChannel
michael@0:      *        The new channel. This channel is not opened yet.
michael@0:      * @param flags
michael@0:      *        Flags indicating the type of redirect. A bitmask consisting
michael@0:      *        of flags from above.
michael@0:      *        One of REDIRECT_TEMPORARY and REDIRECT_PERMANENT will always be
michael@0:      *        set.
michael@0:      * @param callback
michael@0:      *        Object to inform about the async result of this method
michael@0:      *
michael@0:      * @throw <any> Throwing an exception will cause the redirect to be
michael@0:      *        cancelled
michael@0:      */
michael@0:     void asyncOnChannelRedirect(in nsIChannel oldChannel, 
michael@0:                                 in nsIChannel newChannel,
michael@0:                                 in unsigned long flags,
michael@0:                                 in nsIAsyncVerifyRedirectCallback callback);
michael@0: };