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/*
* Copyright (c) 2010 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
(function()
{
function bind(org_cometd)
{
/**
* This client-side extension enables the client to acknowledge to the server
* the messages that the client has received.
* For the acknowledgement to work, the server must be configured with the
* correspondent server-side ack extension. If both client and server support
* the ack extension, then the ack functionality will take place automatically.
* By enabling this extension, all messages arriving from the server will arrive
* via the long poll, so the comet communication will be slightly chattier.
* The fact that all messages will return via long poll means also that the
* messages will arrive with total order, which is not guaranteed if messages
* can arrive via both long poll and normal response.
* Messages are not acknowledged one by one, but instead a group of messages is
* acknowledged when long poll returns.
*/
return org_cometd.AckExtension = function()
{
var _cometd;
var _serverSupportsAcks = false;
var _ackId = -1;
function _debug(text, args)
{
_cometd._debug(text, args);
}
this.registered = function(name, cometd)
{
_cometd = cometd;
_debug('AckExtension: executing registration callback');
};
this.unregistered = function()
{
_debug('AckExtension: executing unregistration callback');
_cometd = null;
};
this.incoming = function(message)
{
var channel = message.channel;
if (channel == '/meta/handshake')
{
_serverSupportsAcks = message.ext && message.ext.ack;
_debug('AckExtension: server supports acks', _serverSupportsAcks);
}
else if (_serverSupportsAcks && channel == '/meta/connect' && message.successful)
{
var ext = message.ext;
if (ext && typeof ext.ack === 'number')
{
_ackId = ext.ack;
_debug('AckExtension: server sent ack id', _ackId);
}
}
return message;
};
this.outgoing = function(message)
{
var channel = message.channel;
if (channel == '/meta/handshake')
{
if (!message.ext)
{
message.ext = {};
}
message.ext.ack = _cometd && _cometd.ackEnabled !== false;
_ackId = -1;
}
else if (_serverSupportsAcks && channel == '/meta/connect')
{
if (!message.ext)
{
message.ext = {};
}
message.ext.ack = _ackId;
_debug('AckExtension: client sending ack id', _ackId);
}
return message;
};
};
}
if (typeof define === 'function' && define.amd)
{
define(['org/cometd'], bind);
}
else
{
bind(org.cometd);
}
})();
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