lib/goog/net/xmlhttpfactory.js

1// Copyright 2010 The Closure Library Authors. All Rights Reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//      http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS-IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15/**
16 * @fileoverview Interface for a factory for creating XMLHttpRequest objects
17 * and metadata about them.
18 * @author dbk@google.com (David Barrett-Kahn)
19 */
20
21goog.provide('goog.net.XmlHttpFactory');
22
23
24
25/**
26 * Abstract base class for an XmlHttpRequest factory.
27 * @constructor
28 */
29goog.net.XmlHttpFactory = function() {
30};
31
32
33/**
34 * Cache of options - we only actually call internalGetOptions once.
35 * @type {Object}
36 * @private
37 */
38goog.net.XmlHttpFactory.prototype.cachedOptions_ = null;
39
40
41/**
42 * @return {!(XMLHttpRequest|GearsHttpRequest)} A new XMLHttpRequest instance.
43 */
44goog.net.XmlHttpFactory.prototype.createInstance = goog.abstractMethod;
45
46
47/**
48 * @return {Object} Options describing how xhr objects obtained from this
49 *     factory should be used.
50 */
51goog.net.XmlHttpFactory.prototype.getOptions = function() {
52  return this.cachedOptions_ ||
53      (this.cachedOptions_ = this.internalGetOptions());
54};
55
56
57/**
58 * Override this method in subclasses to preserve the caching offered by
59 * getOptions().
60 * @return {Object} Options describing how xhr objects obtained from this
61 *     factory should be used.
62 * @protected
63 */
64goog.net.XmlHttpFactory.prototype.internalGetOptions = goog.abstractMethod;