2014-04-21 16:14:28 -04:00
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/**
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* XMLHttpRequest HTTP protocol implementation
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*
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* Copyright (C) 2014 LoVullo Associates, Inc.
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*
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* This file is part of the Liza Data Collection Framework
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*
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* Liza is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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var Class = require( 'easejs' ).Class,
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HttpImpl = require( './HttpImpl' );
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/**
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* An HTTP implementation using the standardized XMLHttpRequest prototype.
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*/
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module.exports = Class( 'XhrHttpImpl' )
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.implement( HttpImpl )
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.extend(
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{
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/**
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* XMLHttpRequest constructor
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* @type {XMLHttpRequest}
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* @constructor
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*/
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'private _Xhr': null,
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/**
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* Initializes with constructor to the object through which XHRs will be
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* made
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*
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* @param {Object} XMLHttpRequest ctor to object to perform requests
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*/
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__construct: function( XMLHttpRequest )
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{
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this._Xhr = XMLHttpRequest;
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},
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/**
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* Perform HTTP request using the standard XMLHttpRequest
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*
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* @param {Object|string} data request params
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* @param {function(Error, Object)} callback server response callback
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*
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* @return {HttpImpl} self
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*/
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'public requestData': function( url, method, data, callback )
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{
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var req = new this._Xhr();
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try
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{
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this.openRequest( req, url, method );
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this.onLoad( req, function( err, resp )
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{
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callback( err, resp );
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} );
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}
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catch ( e )
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{
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callback( e, null );
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}
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return this;
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},
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/**
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* Prepares a request to the given URL using the given HTTP method
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*
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* This method may be overridden by subtypes to set authentication data,
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* modify headers, hook XHR callbacks, etc.
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*
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* Subtypes may throw exceptions; the caller of this method catches and
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* properly forwards them to the callback.
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*
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* This method must be synchronous.
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*
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* @param {XMLHttpRequest} req request to prepare
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* @param {string} url destination URL
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* @param {string} method HTTP method
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*
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* @return {undefined}
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*/
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'virtual protected openRequest': function( req, url, method )
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{
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// alway async
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req.open( method, url, true );
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},
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/**
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* Hooks ready state change to handle data
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*
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* Subtypes may override this method to alter the ready state change
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2015-05-12 13:53:46 -04:00
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* actions taken (e.g. to display progress, handle errors, etc.) If
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* only the HTTP status needs to be checked, subtypes may override
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* success/failure determination via `#isSuccessful'.
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2014-04-21 16:14:28 -04:00
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*
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* @param {XMLHttpRequest} req request to hook
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* @param {function(string)} callback continuation to invoke with response
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*
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* @return {undefined}
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*
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* @throws {Error} if non-200 response received from server
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*/
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'virtual protected onLoad': function( req, callback )
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{
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2015-05-12 13:53:46 -04:00
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var _self = this;
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2014-04-21 16:14:28 -04:00
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req.onreadystatechange = function()
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{
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// ready state of 4 (DONE) indicates that the request is complete
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if ( req.readyState !== 4 )
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{
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return;
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}
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2015-05-12 13:53:46 -04:00
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else if ( !( _self.isSuccessful( req.status ) ) )
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2014-04-21 16:14:28 -04:00
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{
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callback(
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Error( req.status + " error from server" ),
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{
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status: req.status,
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data: req.responseText
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}
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);
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return;
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}
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// successful
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callback( null, req.responseText );
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};
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2015-05-12 13:53:46 -04:00
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},
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/**
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* Determine whether the given HTTP status indicates a success or
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* failure
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*
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2015-05-12 14:06:02 -04:00
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* The default implementation is to consider any 2xx status code to be
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* successful, as indicated by RFC 2616.
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*
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2015-05-12 13:53:46 -04:00
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* @param {number} status HTTP response status
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*
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* @return {bool} whether HTTP status represents a success
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*/
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'virtual protected isSuccessful': function( status )
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{
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2015-05-12 14:06:02 -04:00
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return ( +status >= 200 ) && ( +status < 300 );
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2014-04-21 16:14:28 -04:00
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}
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} );
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