1 | /* |
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2 | * Timemap.js Copyright 2008 Nick Rabinowitz. |
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3 | * Licensed under the MIT License (see LICENSE.txt) |
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4 | */ |
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5 | |
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6 | /** |
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7 | * @fileOverview |
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8 | * JSON Loaders (JSONP, JSON String) |
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9 | * |
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10 | * @author Nick Rabinowitz (www.nickrabinowitz.com) |
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11 | */ |
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12 | |
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13 | // for JSLint |
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14 | /*global TimeMap */ |
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15 | |
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16 | /** |
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17 | * @class |
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18 | * JSONP loader class - expects a service that takes a callback function name as |
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19 | * the last URL parameter. |
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20 | * |
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21 | * <p>The jsonp loader assumes that the JSON can be loaded from a url to which a |
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22 | * callback function name can be appended, e.g. "http://www.test.com/getsomejson.php?callback=" |
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23 | * The loader then appends a nonce function name which the JSON should include. |
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24 | * This works for services like Google Spreadsheets, etc., and accepts remote URLs.</p> |
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25 | * |
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26 | * @example Usage in TimeMap.init(): |
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27 | |
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28 | datasets: [ |
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29 | { |
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30 | title: "JSONP Dataset", |
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31 | type: "jsonp", |
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32 | options: { |
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33 | url: "http://www.test.com/getsomejson.php?callback=" |
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34 | } |
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35 | } |
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36 | ] |
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37 | * |
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38 | * @constructor |
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39 | * @param {Object} options All options for the loader:<pre> |
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40 | * {Array} url URL of JSON service to load, callback name left off |
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41 | * {Function} preloadFunction Function to call on data before loading |
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42 | * {Function} transformFunction Function to call on individual items before loading |
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43 | * </pre> |
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44 | */ |
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45 | TimeMap.loaders.jsonp = function(options) { |
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46 | // get standard functions and document |
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47 | TimeMap.loaders.mixin(this, options); |
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48 | |
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49 | /** |
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50 | * Function to call on data object before loading |
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51 | * @name TimeMap.loaders.jsonp#preload |
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52 | * @function |
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53 | * @parameter {Object} data Data to preload |
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54 | * @return {Array} data Array of item data |
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55 | */ |
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56 | |
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57 | /** |
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58 | * Function to call on a single item data object before loading |
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59 | * @name TimeMap.loaders.jsonp#transform |
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60 | * @function |
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61 | * @parameter {Object} data Data to transform |
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62 | * @return {Object} data Transformed data for one item |
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63 | */ |
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64 | |
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65 | /** |
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66 | * URL to load, with missing callback parameter |
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67 | * @example "http://www.example.com/myjsonservice?callback=" |
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68 | * @type String |
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69 | */ |
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70 | this.url = options.url; |
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71 | }; |
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72 | |
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73 | /** |
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74 | * JSONP load function. |
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75 | * |
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76 | * @param {TimeMapDataset} dataset Dataset to load data into |
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77 | * @param {Function} callback Function to call once data is loaded |
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78 | */ |
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79 | TimeMap.loaders.jsonp.prototype.load = function(dataset, callback) { |
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80 | var loader = this; |
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81 | // get items |
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82 | TimeMap.loaders.jsonp.read(this.url, function(result) { |
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83 | // load |
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84 | var items = loader.preload(result); |
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85 | dataset.loadItems(items, loader.transform); |
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86 | // callback |
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87 | callback(); |
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88 | }); |
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89 | }; |
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90 | |
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91 | /** |
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92 | * Static - for naming callback functions |
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93 | * @type int |
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94 | */ |
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95 | TimeMap.loaders.jsonp.counter = 0; |
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96 | |
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97 | /** |
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98 | * Static - reads JSON from a URL, assuming that the service is set up to apply |
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99 | * a callback function specified in the URL parameters. |
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100 | * |
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101 | * @param {String} jsonUrl URL to load, missing the callback function name |
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102 | * @param {function} f Callback function to apply to returned data |
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103 | */ |
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104 | TimeMap.loaders.jsonp.read = function(url, f) { |
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105 | // Define a unique function name |
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106 | var callbackName = "_" + TimeMap.loaders.jsonp.counter++; |
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107 | |
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108 | TimeMap.loaders.jsonp[callbackName] = function(result) { |
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109 | // Pass result to user function |
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110 | f(result); |
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111 | // Delete the callback function |
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112 | delete TimeMap.loaders.jsonp[callbackName]; |
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113 | }; |
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114 | |
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115 | // Create a script tag, set its src attribute and add it to the document |
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116 | // This triggers the HTTP request and submits the query |
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117 | var script = document.createElement("script"); |
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118 | script.src = url + "TimeMap.loaders.jsonp." + callbackName; |
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119 | document.body.appendChild(script); |
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120 | }; |
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121 | |
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122 | /** |
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123 | * Static - cancel all current JSONP requests |
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124 | * (note that this doesn't cancel the load, just the callback) |
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125 | */ |
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126 | TimeMap.loaders.jsonp.cancelAll = function() { |
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127 | var namespace = TimeMap.loaders.jsonp; |
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128 | for (var i in namespace){ |
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129 | // XXX: this is too cludgy - callback functions need their own namespace |
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130 | if (i.substr(0,1) == '_'){ |
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131 | namespace[i] = function(){ |
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132 | delete namespace[i]; |
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133 | }; |
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134 | } |
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135 | } |
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136 | }; |
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137 | |
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138 | /** |
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139 | * @class |
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140 | * JSON string loader factory - expects a plain JSON array. |
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141 | * |
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142 | * <p>The json_string loader assumes an array of items in plain JSON, with no |
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143 | * callback function - this will require a local URL.</p> |
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144 | * <p>Note that this loader requires lib/json2.pack.js.</p> |
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145 | * |
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146 | * @augments TimeMap.loaders.remote |
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147 | * |
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148 | * @requires lib/json2.pack.js |
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149 | * |
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150 | * @example Usage in TimeMap.init(): |
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151 | |
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152 | datasets: [ |
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153 | { |
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154 | title: "JSON String Dataset", |
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155 | type: "json_string", |
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156 | options: { |
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157 | url: "mydata.json" // Must be a local URL |
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158 | } |
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159 | } |
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160 | ] |
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161 | * |
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162 | * @param {Object} options All options for the loader:<pre> |
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163 | * {Array} url URL of JSON service to load, callback name left off |
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164 | * {Function} preloadFunction Function to call on data before loading |
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165 | * {Function} transformFunction Function to call on individual items before loading |
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166 | * </pre> |
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167 | * @return {TimeMap.loaders.remote} Remote loader configured for JSON strings |
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168 | */ |
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169 | TimeMap.loaders.json_string = function(options) { |
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170 | var loader = new TimeMap.loaders.remote(options); |
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171 | |
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172 | /** |
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173 | * Parse a JSON string into a JavaScript object, using the json2.js library. |
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174 | * @name TimeMap.loaders.json_string#parse |
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175 | * @param {String} json JSON string to parse |
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176 | * @returns {Object} Parsed JavaScript object |
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177 | */ |
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178 | loader.parse = JSON.parse; |
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179 | |
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180 | return loader; |
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181 | }; |
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182 | |
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183 | // Probably the default json loader should be json_string, not |
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184 | // jsonp. I may change this in the future, so I'd encourage you to use |
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185 | // the specific one you want. |
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186 | TimeMap.loaders.json = TimeMap.loaders.jsonp; |
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