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Lift Framework example source code file (connection.js)

This example Lift Framework source code file (connection.js) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lift Framework tags/keywords

abort_code, abort_code, abort_error, abort_error, comm_code, comm_error, comm_error, content, get, no, post, post, see, xmlhttprequest

The Lift Framework connection.js source code

/*
Copyright (c) 2008, Yahoo! Inc. All rights reserved.
Code licensed under the BSD License:
http://developer.yahoo.net/yui/license.txt
version: 2.6.0
*/
/**
 * The Connection Manager provides a simplified interface to the XMLHttpRequest
 * object.  It handles cross-browser instantiantion of XMLHttpRequest, negotiates the
 * interactive states and server response, returning the results to a pre-defined
 * callback you create.
 *
 * @namespace YAHOO.util
 * @module connection
 * @requires yahoo
 * @requires event
 */

/**
 * The Connection Manager singleton provides methods for creating and managing
 * asynchronous transactions.
 *
 * @class Connect
 */

YAHOO.util.Connect =
{
  /**
   * @description Array of MSFT ActiveX ids for XMLHttpRequest.
   * @property _msxml_progid
   * @private
   * @static
   * @type array
   */
	_msxml_progid:[
		'Microsoft.XMLHTTP',
		'MSXML2.XMLHTTP.3.0',
		'MSXML2.XMLHTTP'
		],

  /**
   * @description Object literal of HTTP header(s)
   * @property _http_header
   * @private
   * @static
   * @type object
   */
	_http_headers:{},

  /**
   * @description Determines if HTTP headers are set.
   * @property _has_http_headers
   * @private
   * @static
   * @type boolean
   */
	_has_http_headers:false,

 /**
  * @description Determines if a default header of
  * Content-Type of 'application/x-www-form-urlencoded'
  * will be added to any client HTTP headers sent for POST
  * transactions.
  * @property _use_default_post_header
  * @private
  * @static
  * @type boolean
  */
    _use_default_post_header:true,

 /**
  * @description The default header used for POST transactions.
  * @property _default_post_header
  * @private
  * @static
  * @type boolean
  */
    _default_post_header:'application/x-www-form-urlencoded; charset=UTF-8',

 /**
  * @description The default header used for transactions involving the
  * use of HTML forms.
  * @property _default_form_header
  * @private
  * @static
  * @type boolean
  */
    _default_form_header:'application/x-www-form-urlencoded',

 /**
  * @description Determines if a default header of
  * 'X-Requested-With: XMLHttpRequest'
  * will be added to each transaction.
  * @property _use_default_xhr_header
  * @private
  * @static
  * @type boolean
  */
    _use_default_xhr_header:true,

 /**
  * @description The default header value for the label
  * "X-Requested-With".  This is sent with each
  * transaction, by default, to identify the
  * request as being made by YUI Connection Manager.
  * @property _default_xhr_header
  * @private
  * @static
  * @type boolean
  */
    _default_xhr_header:'XMLHttpRequest',

 /**
  * @description Determines if custom, default headers
  * are set for each transaction.
  * @property _has_default_header
  * @private
  * @static
  * @type boolean
  */
    _has_default_headers:true,

 /**
  * @description Determines if custom, default headers
  * are set for each transaction.
  * @property _has_default_header
  * @private
  * @static
  * @type boolean
  */
    _default_headers:{},

 /**
  * @description Property modified by setForm() to determine if the data
  * should be submitted as an HTML form.
  * @property _isFormSubmit
  * @private
  * @static
  * @type boolean
  */
    _isFormSubmit:false,

 /**
  * @description Property modified by setForm() to determine if a file(s)
  * upload is expected.
  * @property _isFileUpload
  * @private
  * @static
  * @type boolean
  */
    _isFileUpload:false,

 /**
  * @description Property modified by setForm() to set a reference to the HTML
  * form node if the desired action is file upload.
  * @property _formNode
  * @private
  * @static
  * @type object
  */
    _formNode:null,

 /**
  * @description Property modified by setForm() to set the HTML form data
  * for each transaction.
  * @property _sFormData
  * @private
  * @static
  * @type string
  */
    _sFormData:null,

 /**
  * @description Collection of polling references to the polling mechanism in handleReadyState.
  * @property _poll
  * @private
  * @static
  * @type object
  */
    _poll:{},

 /**
  * @description Queue of timeout values for each transaction callback with a defined timeout value.
  * @property _timeOut
  * @private
  * @static
  * @type object
  */
    _timeOut:{},

  /**
   * @description The polling frequency, in milliseconds, for HandleReadyState.
   * when attempting to determine a transaction's XHR readyState.
   * The default is 50 milliseconds.
   * @property _polling_interval
   * @private
   * @static
   * @type int
   */
     _polling_interval:50,

  /**
   * @description A transaction counter that increments the transaction id for each transaction.
   * @property _transaction_id
   * @private
   * @static
   * @type int
   */
     _transaction_id:0,

  /**
   * @description Tracks the name-value pair of the "clicked" submit button if multiple submit
   * buttons are present in an HTML form; and, if YAHOO.util.Event is available.
   * @property _submitElementValue
   * @private
   * @static
   * @type string
   */
	 _submitElementValue:null,

  /**
   * @description Determines whether YAHOO.util.Event is available and returns true or false.
   * If true, an event listener is bound at the document level to trap click events that
   * resolve to a target type of "Submit".  This listener will enable setForm() to determine
   * the clicked "Submit" value in a multi-Submit button, HTML form.
   * @property _hasSubmitListener
   * @private
   * @static
   */
	 _hasSubmitListener:(function()
	 {
		if(YAHOO.util.Event){
			YAHOO.util.Event.addListener(
				document,
				'click',
				function(e){
					var obj = YAHOO.util.Event.getTarget(e);
					if(obj.nodeName.toLowerCase() == 'input' && (obj.type && obj.type.toLowerCase() == 'submit')){
						YAHOO.util.Connect._submitElementValue = encodeURIComponent(obj.name) + "=" + encodeURIComponent(obj.value);
					}
				});
			return true;
	    }
	    return false;
	 })(),

  /**
   * @description Custom event that fires at the start of a transaction
   * @property startEvent
   * @private
   * @static
   * @type CustomEvent
   */
	startEvent: new YAHOO.util.CustomEvent('start'),

  /**
   * @description Custom event that fires when a transaction response has completed.
   * @property completeEvent
   * @private
   * @static
   * @type CustomEvent
   */
	completeEvent: new YAHOO.util.CustomEvent('complete'),

  /**
   * @description Custom event that fires when handleTransactionResponse() determines a
   * response in the HTTP 2xx range.
   * @property successEvent
   * @private
   * @static
   * @type CustomEvent
   */
	successEvent: new YAHOO.util.CustomEvent('success'),

  /**
   * @description Custom event that fires when handleTransactionResponse() determines a
   * response in the HTTP 4xx/5xx range.
   * @property failureEvent
   * @private
   * @static
   * @type CustomEvent
   */
	failureEvent: new YAHOO.util.CustomEvent('failure'),

  /**
   * @description Custom event that fires when handleTransactionResponse() determines a
   * response in the HTTP 4xx/5xx range.
   * @property failureEvent
   * @private
   * @static
   * @type CustomEvent
   */
	uploadEvent: new YAHOO.util.CustomEvent('upload'),

  /**
   * @description Custom event that fires when a transaction is successfully aborted.
   * @property abortEvent
   * @private
   * @static
   * @type CustomEvent
   */
	abortEvent: new YAHOO.util.CustomEvent('abort'),

  /**
   * @description A reference table that maps callback custom events members to its specific
   * event name.
   * @property _customEvents
   * @private
   * @static
   * @type object
   */
	_customEvents:
	{
		onStart:['startEvent', 'start'],
		onComplete:['completeEvent', 'complete'],
		onSuccess:['successEvent', 'success'],
		onFailure:['failureEvent', 'failure'],
		onUpload:['uploadEvent', 'upload'],
		onAbort:['abortEvent', 'abort']
	},

  /**
   * @description Member to add an ActiveX id to the existing xml_progid array.
   * In the event(unlikely) a new ActiveX id is introduced, it can be added
   * without internal code modifications.
   * @method setProgId
   * @public
   * @static
   * @param {string} id The ActiveX id to be added to initialize the XHR object.
   * @return void
   */
	setProgId:function(id)
	{
		this._msxml_progid.unshift(id);
	},

  /**
   * @description Member to override the default POST header.
   * @method setDefaultPostHeader
   * @public
   * @static
   * @param {boolean} b Set and use default header - true or false .
   * @return void
   */
	setDefaultPostHeader:function(b)
	{
		if(typeof b == 'string'){
			this._default_post_header = b;
		}
		else if(typeof b == 'boolean'){
			this._use_default_post_header = b;
		}
	},

  /**
   * @description Member to override the default transaction header..
   * @method setDefaultXhrHeader
   * @public
   * @static
   * @param {boolean} b Set and use default header - true or false .
   * @return void
   */
	setDefaultXhrHeader:function(b)
	{
		if(typeof b == 'string'){
			this._default_xhr_header = b;
		}
		else{
			this._use_default_xhr_header = b;
		}
	},

  /**
   * @description Member to modify the default polling interval.
   * @method setPollingInterval
   * @public
   * @static
   * @param {int} i The polling interval in milliseconds.
   * @return void
   */
	setPollingInterval:function(i)
	{
		if(typeof i == 'number' && isFinite(i)){
			this._polling_interval = i;
		}
	},

  /**
   * @description Instantiates a XMLHttpRequest object and returns an object with two properties:
   * the XMLHttpRequest instance and the transaction id.
   * @method createXhrObject
   * @private
   * @static
   * @param {int} transactionId Property containing the transaction id for this transaction.
   * @return object
   */
	createXhrObject:function(transactionId)
	{
		var obj,http;
		try
		{
			// Instantiates XMLHttpRequest in non-IE browsers and assigns to http.
			http = new XMLHttpRequest();
			//  Object literal with http and tId properties
			obj = { conn:http, tId:transactionId };
		}
		catch(e)
		{
			for(var i=0; i<this._msxml_progid.length; ++i){
				try
				{
					// Instantiates XMLHttpRequest for IE and assign to http
					http = new ActiveXObject(this._msxml_progid[i]);
					//  Object literal with conn and tId properties
					obj = { conn:http, tId:transactionId };
					break;
				}
				catch(e2){}
			}
		}
		finally
		{
			return obj;
		}
	},

  /**
   * @description This method is called by asyncRequest to create a
   * valid connection object for the transaction.  It also passes a
   * transaction id and increments the transaction id counter.
   * @method getConnectionObject
   * @private
   * @static
   * @return {object}
   */
	getConnectionObject:function(isFileUpload)
	{
		var o;
		var tId = this._transaction_id;

		try
		{
			if(!isFileUpload){
				o = this.createXhrObject(tId);
			}
			else{
				o = {};
				o.tId = tId;
				o.isUpload = true;
			}

			if(o){
				this._transaction_id++;
			}
		}
		catch(e){}
		finally
		{
			return o;
		}
	},

  /**
   * @description Method for initiating an asynchronous request via the XHR object.
   * @method asyncRequest
   * @public
   * @static
   * @param {string} method HTTP transaction method
   * @param {string} uri Fully qualified path of resource
   * @param {callback} callback User-defined callback function or object
   * @param {string} postData POST body
   * @return {object} Returns the connection object
   */
	asyncRequest:function(method, uri, callback, postData)
	{
		var o = (this._isFileUpload)?this.getConnectionObject(true):this.getConnectionObject();
		var args = (callback && callback.argument)?callback.argument:null;

		if(!o){
			return null;
		}
		else{

			// Intialize any transaction-specific custom events, if provided.
			if(callback && callback.customevents){
				this.initCustomEvents(o, callback);
			}

			if(this._isFormSubmit){
				if(this._isFileUpload){
					this.uploadFile(o, callback, uri, postData);
					return o;
				}

				// If the specified HTTP method is GET, setForm() will return an
				// encoded string that is concatenated to the uri to
				// create a querystring.
				if(method.toUpperCase() == 'GET'){
					if(this._sFormData.length !== 0){
						// If the URI already contains a querystring, append an ampersand
						// and then concatenate _sFormData to the URI.
						uri += ((uri.indexOf('?') == -1)?'?':'&') + this._sFormData;
					}
				}
				else if(method.toUpperCase() == 'POST'){
					// If POST data exist in addition to the HTML form data,
					// it will be concatenated to the form data.
					postData = postData?this._sFormData + "&" + postData:this._sFormData;
				}
			}

			if(method.toUpperCase() == 'GET' && (callback && callback.cache === false)){
				// If callback.cache is defined and set to false, a
				// timestamp value will be added to the querystring.
				uri += ((uri.indexOf('?') == -1)?'?':'&') + "rnd=" + new Date().valueOf().toString();
			}

			o.conn.open(method, uri, true);

			// Each transaction will automatically include a custom header of
			// "X-Requested-With: XMLHttpRequest" to identify the request as
			// having originated from Connection Manager.
			if(this._use_default_xhr_header){
				if(!this._default_headers['X-Requested-With']){
					this.initHeader('X-Requested-With', this._default_xhr_header, true);
				}
			}

			//If the transaction method is POST and the POST header value is set to true
			//or a custom value, initalize the Content-Type header to this value.
			if((method.toUpperCase() === 'POST' && this._use_default_post_header) && this._isFormSubmit === false){
				this.initHeader('Content-Type', this._default_post_header);
			}

			//Initialize all default and custom HTTP headers,
			if(this._has_default_headers || this._has_http_headers){
				this.setHeader(o);
			}

			this.handleReadyState(o, callback);
			o.conn.send(postData || '');


			// Reset the HTML form data and state properties as
			// soon as the data are submitted.
			if(this._isFormSubmit === true){
				this.resetFormState();
			}

			// Fire global custom event -- startEvent
			this.startEvent.fire(o, args);

			if(o.startEvent){
				// Fire transaction custom event -- startEvent
				o.startEvent.fire(o, args);
			}

			return o;
		}
	},

  /**
   * @description This method creates and subscribes custom events,
   * specific to each transaction
   * @method initCustomEvents
   * @private
   * @static
   * @param {object} o The connection object
   * @param {callback} callback The user-defined callback object
   * @return {void}
   */
	initCustomEvents:function(o, callback)
	{
		var prop;
		// Enumerate through callback.customevents members and bind/subscribe
		// events that match in the _customEvents table.
		for(prop in callback.customevents){
			if(this._customEvents[prop][0]){
				// Create the custom event
				o[this._customEvents[prop][0]] = new YAHOO.util.CustomEvent(this._customEvents[prop][1], (callback.scope)?callback.scope:null);

				// Subscribe the custom event
				o[this._customEvents[prop][0]].subscribe(callback.customevents[prop]);
			}
		}
	},

  /**
   * @description This method serves as a timer that polls the XHR object's readyState
   * property during a transaction, instead of binding a callback to the
   * onreadystatechange event.  Upon readyState 4, handleTransactionResponse
   * will process the response, and the timer will be cleared.
   * @method handleReadyState
   * @private
   * @static
   * @param {object} o The connection object
   * @param {callback} callback The user-defined callback object
   * @return {void}
   */

    handleReadyState:function(o, callback)

    {
		var oConn = this;
		var args = (callback && callback.argument)?callback.argument:null;

		if(callback && callback.timeout){
			this._timeOut[o.tId] = window.setTimeout(function(){ oConn.abort(o, callback, true); }, callback.timeout);
		}

		this._poll[o.tId] = window.setInterval(
			function(){
				if(o.conn && o.conn.readyState === 4){

					// Clear the polling interval for the transaction
					// and remove the reference from _poll.
					window.clearInterval(oConn._poll[o.tId]);
					delete oConn._poll[o.tId];

					if(callback && callback.timeout){
						window.clearTimeout(oConn._timeOut[o.tId]);
						delete oConn._timeOut[o.tId];
					}

					// Fire global custom event -- completeEvent
					oConn.completeEvent.fire(o, args);

					if(o.completeEvent){
						// Fire transaction custom event -- completeEvent
						o.completeEvent.fire(o, args);
					}

					oConn.handleTransactionResponse(o, callback);
				}
			}
		,this._polling_interval);
    },

  /**
   * @description This method attempts to interpret the server response and
   * determine whether the transaction was successful, or if an error or
   * exception was encountered.
   * @method handleTransactionResponse
   * @private
   * @static
   * @param {object} o The connection object
   * @param {object} callback The user-defined callback object
   * @param {boolean} isAbort Determines if the transaction was terminated via abort().
   * @return {void}
   */
    handleTransactionResponse:function(o, callback, isAbort)
    {
		var httpStatus, responseObject;
		var args = (callback && callback.argument)?callback.argument:null;

		try
		{
			if(o.conn.status !== undefined && o.conn.status !== 0){
				httpStatus = o.conn.status;
			}
			else{
				httpStatus = 13030;
			}
		}
		catch(e){

			 // 13030 is a custom code to indicate the condition -- in Mozilla/FF --
			 // when the XHR object's status and statusText properties are
			 // unavailable, and a query attempt throws an exception.
			httpStatus = 13030;
		}

		if(httpStatus >= 200 && httpStatus < 300 || httpStatus === 1223){
			responseObject = this.createResponseObject(o, args);
			if(callback && callback.success){
				if(!callback.scope){
					callback.success(responseObject);
				}
				else{
					// If a scope property is defined, the callback will be fired from
					// the context of the object.
					callback.success.apply(callback.scope, [responseObject]);
				}
			}

			// Fire global custom event -- successEvent
			this.successEvent.fire(responseObject);

			if(o.successEvent){
				// Fire transaction custom event -- successEvent
				o.successEvent.fire(responseObject);
			}
		}
		else{
			switch(httpStatus){
				// The following cases are wininet.dll error codes that may be encountered.
				case 12002: // Server timeout
				case 12029: // 12029 to 12031 correspond to dropped connections.
				case 12030:
				case 12031:
				case 12152: // Connection closed by server.
				case 13030: // See above comments for variable status.
					responseObject = this.createExceptionObject(o.tId, args, (isAbort?isAbort:false));
					if(callback && callback.failure){
						if(!callback.scope){
							callback.failure(responseObject);
						}
						else{
							callback.failure.apply(callback.scope, [responseObject]);
						}
					}

					break;
				default:
					responseObject = this.createResponseObject(o, args);
					if(callback && callback.failure){
						if(!callback.scope){
							callback.failure(responseObject);
						}
						else{
							callback.failure.apply(callback.scope, [responseObject]);
						}
					}
			}

			// Fire global custom event -- failureEvent
			this.failureEvent.fire(responseObject);

			if(o.failureEvent){
				// Fire transaction custom event -- failureEvent
				o.failureEvent.fire(responseObject);
			}

		}

		this.releaseObject(o);
		responseObject = null;
    },

  /**
   * @description This method evaluates the server response, creates and returns the results via
   * its properties.  Success and failure cases will differ in the response
   * object's property values.
   * @method createResponseObject
   * @private
   * @static
   * @param {object} o The connection object
   * @param {callbackArg} callbackArg The user-defined argument or arguments to be passed to the callback
   * @return {object}
   */
    createResponseObject:function(o, callbackArg)
    {
		var obj = {};
		var headerObj = {};

		try
		{
			var headerStr = o.conn.getAllResponseHeaders();
			var header = headerStr.split('\n');
			for(var i=0; i<header.length; i++){
				var delimitPos = header[i].indexOf(':');
				if(delimitPos != -1){
					headerObj[header[i].substring(0,delimitPos)] = header[i].substring(delimitPos+2);
				}
			}
		}
		catch(e){}

		obj.tId = o.tId;
		// Normalize IE's response to HTTP 204 when Win error 1223.
		obj.status = (o.conn.status == 1223)?204:o.conn.status;
		// Normalize IE's statusText to "No Content" instead of "Unknown".
		obj.statusText = (o.conn.status == 1223)?"No Content":o.conn.statusText;
		obj.getResponseHeader = headerObj;
		obj.getAllResponseHeaders = headerStr;
		obj.responseText = o.conn.responseText;
		obj.responseXML = o.conn.responseXML;

		if(callbackArg){
			obj.argument = callbackArg;
		}

		return obj;
    },

  /**
   * @description If a transaction cannot be completed due to dropped or closed connections,
   * there may be not be enough information to build a full response object.
   * The failure callback will be fired and this specific condition can be identified
   * by a status property value of 0.
   *
   * If an abort was successful, the status property will report a value of -1.
   *
   * @method createExceptionObject
   * @private
   * @static
   * @param {int} tId The Transaction Id
   * @param {callbackArg} callbackArg The user-defined argument or arguments to be passed to the callback
   * @param {boolean} isAbort Determines if the exception case is caused by a transaction abort
   * @return {object}
   */
    createExceptionObject:function(tId, callbackArg, isAbort)
    {
		var COMM_CODE = 0;
		var COMM_ERROR = 'communication failure';
		var ABORT_CODE = -1;
		var ABORT_ERROR = 'transaction aborted';

		var obj = {};

		obj.tId = tId;
		if(isAbort){
			obj.status = ABORT_CODE;
			obj.statusText = ABORT_ERROR;
		}
		else{
			obj.status = COMM_CODE;
			obj.statusText = COMM_ERROR;
		}

		if(callbackArg){
			obj.argument = callbackArg;
		}

		return obj;
    },

  /**
   * @description Method that initializes the custom HTTP headers for the each transaction.
   * @method initHeader
   * @public
   * @static
   * @param {string} label The HTTP header label
   * @param {string} value The HTTP header value
   * @param {string} isDefault Determines if the specific header is a default header
   * automatically sent with each transaction.
   * @return {void}
   */
	initHeader:function(label, value, isDefault)
	{
		var headerObj = (isDefault)?this._default_headers:this._http_headers;
		headerObj[label] = value;

		if(isDefault){
			this._has_default_headers = true;
		}
		else{
			this._has_http_headers = true;
		}
	},


  /**
   * @description Accessor that sets the HTTP headers for each transaction.
   * @method setHeader
   * @private
   * @static
   * @param {object} o The connection object for the transaction.
   * @return {void}
   */
	setHeader:function(o)
	{
		var prop;
		if(this._has_default_headers){
			for(prop in this._default_headers){
				if(YAHOO.lang.hasOwnProperty(this._default_headers, prop)){
					o.conn.setRequestHeader(prop, this._default_headers[prop]);
				}
			}
		}

		if(this._has_http_headers){
			for(prop in this._http_headers){
				if(YAHOO.lang.hasOwnProperty(this._http_headers, prop)){
					o.conn.setRequestHeader(prop, this._http_headers[prop]);
				}
			}
			delete this._http_headers;

			this._http_headers = {};
			this._has_http_headers = false;
		}
	},

  /**
   * @description Resets the default HTTP headers object
   * @method resetDefaultHeaders
   * @public
   * @static
   * @return {void}
   */
	resetDefaultHeaders:function(){
		delete this._default_headers;
		this._default_headers = {};
		this._has_default_headers = false;
	},

  /**
   * @description This method assembles the form label and value pairs and
   * constructs an encoded string.
   * asyncRequest() will automatically initialize the transaction with a
   * a HTTP header Content-Type of application/x-www-form-urlencoded.
   * @method setForm
   * @public
   * @static
   * @param {string || object} form id or name attribute, or form object.
   * @param {boolean} optional enable file upload.
   * @param {boolean} optional enable file upload over SSL in IE only.
   * @return {string} string of the HTML form field name and value pairs..
   */
	setForm:function(formId, isUpload, secureUri)
	{
        var oForm, oElement, oName, oValue, oDisabled,
            hasSubmit = false,
            data = [], item = 0,
            i,len,j,jlen,opt;

		this.resetFormState();

		if(typeof formId == 'string'){
			// Determine if the argument is a form id or a form name.
			// Note form name usage is deprecated by supported
			// here for legacy reasons.
			oForm = (document.getElementById(formId) || document.forms[formId]);
		}
		else if(typeof formId == 'object'){
			// Treat argument as an HTML form object.
			oForm = formId;
		}
		else{
			return;
		}

		// If the isUpload argument is true, setForm will call createFrame to initialize
		// an iframe as the form target.
		//
		// The argument secureURI is also required by IE in SSL environments
		// where the secureURI string is a fully qualified HTTP path, used to set the source
		// of the iframe, to a stub resource in the same domain.
		if(isUpload){

			// Create iframe in preparation for file upload.
			this.createFrame(secureUri?secureUri:null);

			// Set form reference and file upload properties to true.
			this._isFormSubmit = true;
			this._isFileUpload = true;
			this._formNode = oForm;

			return;

		}

		// Iterate over the form elements collection to construct the
		// label-value pairs.
		for (i=0,len=oForm.elements.length; i<len; ++i){
			oElement  = oForm.elements[i];
			oDisabled = oElement.disabled;
            oName     = oElement.name;

			// Do not submit fields that are disabled or
			// do not have a name attribute value.
			if(!oDisabled && oName)
			{
                oName  = encodeURIComponent(oName)+'=';
                oValue = encodeURIComponent(oElement.value);

				switch(oElement.type)
				{
                    // Safari, Opera, FF all default opt.value from .text if
                    // value attribute not specified in markup
					case 'select-one':
                        if (oElement.selectedIndex > -1) {
                            opt = oElement.options[oElement.selectedIndex];
                            data[item++] = oName + encodeURIComponent(
                                (opt.attributes.value && opt.attributes.value.specified) ? opt.value : opt.text);
                        }
                        break;
					case 'select-multiple':
                        if (oElement.selectedIndex > -1) {
                            for(j=oElement.selectedIndex, jlen=oElement.options.length; j<jlen; ++j){
                                opt = oElement.options[j];
                                if (opt.selected) {
                                    data[item++] = oName + encodeURIComponent(
                                        (opt.attributes.value && opt.attributes.value.specified) ? opt.value : opt.text);
                                }
                            }
                        }
						break;
					case 'radio':
					case 'checkbox':
						if(oElement.checked){
                            data[item++] = oName + oValue;
						}
						break;
					case 'file':
						// stub case as XMLHttpRequest will only send the file path as a string.
					case undefined:
						// stub case for fieldset element which returns undefined.
					case 'reset':
						// stub case for input type reset button.
					case 'button':
						// stub case for input type button elements.
						break;
					case 'submit':
						if(hasSubmit === false){
							if(this._hasSubmitListener && this._submitElementValue){
                                data[item++] = this._submitElementValue;
							}
							else{
                                data[item++] = oName + oValue;
							}

							hasSubmit = true;
						}
						break;
					default:
                        data[item++] = oName + oValue;
				}
			}
		}

		this._isFormSubmit = true;
		this._sFormData = data.join('&');


		this.initHeader('Content-Type', this._default_form_header);

		return this._sFormData;
	},

  /**
   * @description Resets HTML form properties when an HTML form or HTML form
   * with file upload transaction is sent.
   * @method resetFormState
   * @private
   * @static
   * @return {void}
   */
	resetFormState:function(){
		this._isFormSubmit = false;
		this._isFileUpload = false;
		this._formNode = null;
		this._sFormData = "";
	},

  /**
   * @description Creates an iframe to be used for form file uploads.  It is remove from the
   * document upon completion of the upload transaction.
   * @method createFrame
   * @private
   * @static
   * @param {string} optional qualified path of iframe resource for SSL in IE.
   * @return {void}
   */
	createFrame:function(secureUri){

		// IE does not allow the setting of id and name attributes as object
		// properties via createElement().  A different iframe creation
		// pattern is required for IE.
		var frameId = 'yuiIO' + this._transaction_id;
		var io;
		if(YAHOO.env.ua.ie){
			io = document.createElement('<iframe id="' + frameId + '" name="' + frameId + '" />');

			// IE will throw a security exception in an SSL environment if the
			// iframe source is undefined.
			if(typeof secureUri == 'boolean'){
				io.src = 'javascript:false';
			}
		}
		else{
			io = document.createElement('iframe');
			io.id = frameId;
			io.name = frameId;
		}

		io.style.position = 'absolute';
		io.style.top = '-1000px';
		io.style.left = '-1000px';

		document.body.appendChild(io);
	},

  /**
   * @description Parses the POST data and creates hidden form elements
   * for each key-value, and appends them to the HTML form object.
   * @method appendPostData
   * @private
   * @static
   * @param {string} postData The HTTP POST data
   * @return {array} formElements Collection of hidden fields.
   */
	appendPostData:function(postData)
	{
		var formElements = [],
			postMessage = postData.split('&'),
			i, delimitPos;
		for(i=0; i < postMessage.length; i++){
			delimitPos = postMessage[i].indexOf('=');
			if(delimitPos != -1){
				formElements[i] = document.createElement('input');
				formElements[i].type = 'hidden';
				formElements[i].name = decodeURIComponent(postMessage[i].substring(0,delimitPos));
				formElements[i].value = decodeURIComponent(postMessage[i].substring(delimitPos+1));
				this._formNode.appendChild(formElements[i]);
			}
		}

		return formElements;
	},

  /**
   * @description Uploads HTML form, inclusive of files/attachments, using the
   * iframe created in createFrame to facilitate the transaction.
   * @method uploadFile
   * @private
   * @static
   * @param {int} id The transaction id.
   * @param {object} callback User-defined callback object.
   * @param {string} uri Fully qualified path of resource.
   * @param {string} postData POST data to be submitted in addition to HTML form.
   * @return {void}
   */
	uploadFile:function(o, callback, uri, postData){

		// Each iframe has an id prefix of "yuiIO" followed
		// by the unique transaction id.
		var frameId = 'yuiIO' + o.tId,
		    uploadEncoding = 'multipart/form-data',
		    io = document.getElementById(frameId),
		    oConn = this,
			args = (callback && callback.argument)?callback.argument:null,
            oElements,i,prop,obj;

		// Track original HTML form attribute values.
		var rawFormAttributes =
		{
			action:this._formNode.getAttribute('action'),
			method:this._formNode.getAttribute('method'),
			target:this._formNode.getAttribute('target')
		};

		// Initialize the HTML form properties in case they are
		// not defined in the HTML form.
		this._formNode.setAttribute('action', uri);
		this._formNode.setAttribute('method', 'POST');
		this._formNode.setAttribute('target', frameId);

		if(YAHOO.env.ua.ie){
			// IE does not respect property enctype for HTML forms.
			// Instead it uses the property - "encoding".
			this._formNode.setAttribute('encoding', uploadEncoding);
		}
		else{
			this._formNode.setAttribute('enctype', uploadEncoding);
		}

		if(postData){
			oElements = this.appendPostData(postData);
		}

		// Start file upload.
		this._formNode.submit();

		// Fire global custom event -- startEvent
		this.startEvent.fire(o, args);

		if(o.startEvent){
			// Fire transaction custom event -- startEvent
			o.startEvent.fire(o, args);
		}

		// Start polling if a callback is present and the timeout
		// property has been defined.
		if(callback && callback.timeout){
			this._timeOut[o.tId] = window.setTimeout(function(){ oConn.abort(o, callback, true); }, callback.timeout);
		}

		// Remove HTML elements created by appendPostData
		if(oElements && oElements.length > 0){
			for(i=0; i < oElements.length; i++){
				this._formNode.removeChild(oElements[i]);
			}
		}

		// Restore HTML form attributes to their original
		// values prior to file upload.
		for(prop in rawFormAttributes){
			if(YAHOO.lang.hasOwnProperty(rawFormAttributes, prop)){
				if(rawFormAttributes[prop]){
					this._formNode.setAttribute(prop, rawFormAttributes[prop]);
				}
				else{
					this._formNode.removeAttribute(prop);
				}
			}
		}

		// Reset HTML form state properties.
		this.resetFormState();

		// Create the upload callback handler that fires when the iframe
		// receives the load event.  Subsequently, the event handler is detached
		// and the iframe removed from the document.
		var uploadCallback = function()
		{
			if(callback && callback.timeout){
				window.clearTimeout(oConn._timeOut[o.tId]);
				delete oConn._timeOut[o.tId];
			}

			// Fire global custom event -- completeEvent
			oConn.completeEvent.fire(o, args);

			if(o.completeEvent){
				// Fire transaction custom event -- completeEvent
				o.completeEvent.fire(o, args);
			}

			obj = {
			    tId : o.tId,
			    argument : callback.argument
            };

			try
			{
				// responseText and responseXML will be populated with the same data from the iframe.
				// Since the HTTP headers cannot be read from the iframe
				obj.responseText = io.contentWindow.document.body?io.contentWindow.document.body.innerHTML:io.contentWindow.document.documentElement.textContent;
				obj.responseXML = io.contentWindow.document.XMLDocument?io.contentWindow.document.XMLDocument:io.contentWindow.document;
			}
			catch(e){}

			if(callback && callback.upload){
				if(!callback.scope){
					callback.upload(obj);
				}
				else{
					callback.upload.apply(callback.scope, [obj]);
				}
			}

			// Fire global custom event -- uploadEvent
			oConn.uploadEvent.fire(obj);

			if(o.uploadEvent){
				// Fire transaction custom event -- uploadEvent
				o.uploadEvent.fire(obj);
			}

			YAHOO.util.Event.removeListener(io, "load", uploadCallback);

			setTimeout(
				function(){
					document.body.removeChild(io);
					oConn.releaseObject(o);
				}, 100);
		};

		// Bind the onload handler to the iframe to detect the file upload response.
		YAHOO.util.Event.addListener(io, "load", uploadCallback);
	},

  /**
   * @description Method to terminate a transaction, if it has not reached readyState 4.
   * @method abort
   * @public
   * @static
   * @param {object} o The connection object returned by asyncRequest.
   * @param {object} callback  User-defined callback object.
   * @param {string} isTimeout boolean to indicate if abort resulted from a callback timeout.
   * @return {boolean}
   */
	abort:function(o, callback, isTimeout)
	{
		var abortStatus;
		var args = (callback && callback.argument)?callback.argument:null;


		if(o && o.conn){
			if(this.isCallInProgress(o)){
				// Issue abort request
				o.conn.abort();

				window.clearInterval(this._poll[o.tId]);
				delete this._poll[o.tId];

				if(isTimeout){
					window.clearTimeout(this._timeOut[o.tId]);
					delete this._timeOut[o.tId];
				}

				abortStatus = true;
			}
		}
		else if(o && o.isUpload === true){
			var frameId = 'yuiIO' + o.tId;
			var io = document.getElementById(frameId);

			if(io){
				// Remove all listeners on the iframe prior to
				// its destruction.
				YAHOO.util.Event.removeListener(io, "load");
				// Destroy the iframe facilitating the transaction.
				document.body.removeChild(io);

				if(isTimeout){
					window.clearTimeout(this._timeOut[o.tId]);
					delete this._timeOut[o.tId];
				}

				abortStatus = true;
			}
		}
		else{
			abortStatus = false;
		}

		if(abortStatus === true){
			// Fire global custom event -- abortEvent
			this.abortEvent.fire(o, args);

			if(o.abortEvent){
				// Fire transaction custom event -- abortEvent
				o.abortEvent.fire(o, args);
			}

			this.handleTransactionResponse(o, callback, true);
		}

		return abortStatus;
	},

  /**
   * @description Determines if the transaction is still being processed.
   * @method isCallInProgress
   * @public
   * @static
   * @param {object} o The connection object returned by asyncRequest
   * @return {boolean}
   */
	isCallInProgress:function(o)
	{
		// if the XHR object assigned to the transaction has not been dereferenced,
		// then check its readyState status.  Otherwise, return false.
		if(o && o.conn){
			return o.conn.readyState !== 4 && o.conn.readyState !== 0;
		}
		else if(o && o.isUpload === true){
			var frameId = 'yuiIO' + o.tId;
			return document.getElementById(frameId)?true:false;
		}
		else{
			return false;
		}
	},

  /**
   * @description Dereference the XHR instance and the connection object after the transaction is completed.
   * @method releaseObject
   * @private
   * @static
   * @param {object} o The connection object
   * @return {void}
   */
	releaseObject:function(o)
	{
		if(o && o.conn){
			//dereference the XHR instance.
			o.conn = null;


			//dereference the connection object.
			o = null;
		}
	}
};
YAHOO.register("connection", YAHOO.util.Connect, {version: "2.6.0", build: "1321"});

Other Lift Framework examples (source code examples)

Here is a short list of links related to this Lift Framework connection.js source code file:



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