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// Copyright 2013 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//      http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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 * @fileoverview Transport support for WebChannel.
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 *
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 * The <code>WebChannelTransport</code> implementation serves as the factory
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 * for <code>WebChannel</code>, which offers an abstraction for
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 * point-to-point socket-like communication similar to what BrowserChannel
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 * or HTML5 WebSocket offers.
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 *
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 */
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goog.provide('goog.net.WebChannelTransport');
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/**
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 * A WebChannelTransport instance represents a shared context of logical
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 * connectivity between a browser client and a remote origin.
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 *
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 * Over a single WebChannelTransport instance, multiple WebChannels may be
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 * created against different URLs, which may all share the same
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 * underlying connectivity (i.e. TCP connection) whenever possible.
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 *
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 * When multi-domains are supported, such as CORS, multiple origins may be
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 * supported over a single WebChannelTransport instance at the same time.
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 *
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 * Sharing between different window contexts such as tabs is not addressed
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 * by WebChannelTransport. Applications may choose HTML5 shared workers
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 * or other techniques to access the same transport instance
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 * across different window contexts.
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 *
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 * @interface
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 */
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goog.net.WebChannelTransport = function() {};
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/**
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 * The client version. This integer value will be passed to the server
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 * when a channel is opened to inform the server the client "capabilities".
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 *
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 * Wire protocol version is a different concept and is internal to the
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 * transport implementation.
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 *
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 * @const
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 * @type {number}
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 */
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goog.net.WebChannelTransport.CLIENT_VERSION = 20;
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/**
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 * Create a new WebChannel instance.
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 *
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 * The new WebChannel is to be opened against the server-side resource
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 * as specified by the given URL. See {@link goog.net.WebChannel} for detailed
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 * semantics.
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 *
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 * @param {string} url The URL path for the new WebChannel instance.
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 * @param {!goog.net.WebChannel.Options=} opt_options Configuration for the
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 *     new WebChannel instance. The configuration object is reusable after
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 *     the new channel instance is created.
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 * @return {!goog.net.WebChannel} the newly created WebChannel instance.
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 */
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goog.net.WebChannelTransport.prototype.createWebChannel = goog.abstractMethod;
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