topical media & game development
professional-web-03-connection.js / js
/*
Copyright (c) 2006, Yahoo! Inc. All rights reserved.
Code licensed under the BSD License:
http://developer.yahoo.net/yui/license.txt
version: 0.11.1
*/
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.
@ class
YAHOO.util.Connect =
{
Array of MSFT ActiveX ids for XMLHttpRequest.
@private
@type array
_msxml_progid:[
'MSXML2.XMLHTTP.3.0',
'MSXML2.XMLHTTP',
'Microsoft.XMLHTTP'
],
Object literal of HTTP header(s)
@private
@type object
_http_header:{},
Determines if HTTP headers are set.
@private
@type boolean
_has_http_headers:false,
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.
@private
@type boolean
_default_post_header:true,
Property modified by setForm() to determine if the data
should be submitted as an HTML form.
@private
@type boolean
_isFormSubmit:false,
Property modified by setForm() to determine if a file(s)
upload is expected.
@private
@type boolean
_isFileUpload:false,
Property modified by setForm() to set a reference to the HTML
form node if the desired action is file upload.
@private
@type object
_formNode:null,
Property modified by setForm() to set the HTML form data
for each transaction.
@private
@type string
_sFormData:null,
Collection of polling references to the polling mechanism in handleReadyState.
@private
@type string
_poll:[],
Queue of timeout values for each transaction callback with a defined timeout value.
@private
@type string
_timeOut:[],
The polling frequency, in milliseconds, for HandleReadyState.
when attempting to determine a transaction's XHR readyState.
The default is 50 milliseconds.
@private
@type int
_polling_interval:50,
A transaction counter that increments the transaction id for each transaction.
@private
@type int
_transaction_id:0,
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.
@public
parameter: string id The ActiveX id to be added to initialize the XHR object.
returns: void
setProgId:function(id)
{
this._msxml_progid.unshift(id);
},
Member to enable or disable the default POST header.
@public
parameter: boolean b Set and use default header - true or false .
returns: void
setDefaultPostHeader:function(b)
{
this._default_post_header = b;
},
Member to modify the default polling interval.
@public
parameter: {int} i The polling interval in milliseconds.
returns: void
setPollingInterval:function(i)
{
if(typeof i == 'number' && isFinite(i)){
this._polling_interval = i;
}
},
Instantiates a XMLHttpRequest object and returns an object with two properties:
the XMLHttpRequest instance and the transaction id.
@private
parameter: {int} transactionId Property containing the transaction id for this transaction.
returns: connection 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 http and tId properties
obj = { conn:http, tId:transactionId };
break;
}
catch(e){}
}
}
finally
{
return obj;
}
},
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.
@private
returns: object
getConnectionObject:function()
{
var o;
var tId = this._transaction_id;
try
{
o = this.createXhrObject(tId);
if(o){
this._transaction_id++;
}
}
catch(e){}
finally
{
return o;
}
},
Method for initiating an asynchronous request via the XHR object.
@public
parameter: {string} method HTTP transaction method
parameter: {string} uri Fully qualified path of resource
parameter: callback User-defined callback function or object
parameter: {string} postData POST body
returns: {object} Returns the connection object
asyncRequest:function(method, uri, callback, postData)
{
var o = this.getConnectionObject();
if(!o){
return null;
}
else{
if(this._isFormSubmit){
if(this._isFileUpload){
this.uploadFile(o.tId, callback, uri);
this.releaseObject(o);
return;
}
//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 == 'GET'){
uri += "?" + this._sFormData;
}
else if(method == 'POST'){
postData = this._sFormData;
}
this._sFormData = '';
}
o.conn.open(method, uri, true);
if(this._isFormSubmit || (postData && this._default_post_header)){
this.initHeader('Content-Type','application/x-www-form-urlencoded');
if(this._isFormSubmit){
this._isFormSubmit = false;
}
}
//Verify whether the transaction has any user-defined HTTP headers
//and set them.
if(this._has_http_headers){
this.setHeader(o);
}
this.handleReadyState(o, callback);
postData?o.conn.send(postData):o.conn.send(null);
return o;
}
},
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.
@private
parameter: {object} o The connection object
parameter: callback User-defined callback object
returns: void
handleReadyState:function(o, callback)
{
var timeOut = callback.timeout;
var oConn = this;
try
{
if(timeOut !== undefined){
this._timeOut[o.tId] = window.setTimeout(function(){ oConn.abort(o, callback, true) }, timeOut);
}
this._poll[o.tId] = window.setInterval(
function(){
if(o.conn && o.conn.readyState == 4){
window.clearInterval(oConn._poll[o.tId]);
oConn._poll.splice(o.tId);
if(timeOut){
oConn._timeOut.splice(o.tId);
}
oConn.handleTransactionResponse(o, callback);
}
}
,this._polling_interval);
}
catch(e)
{
window.clearInterval(oConn._poll[o.tId]);
oConn._poll.splice(o.tId);
if(timeOut){
oConn._timeOut.splice(o.tId);
}
oConn.handleTransactionResponse(o, callback);
}
},
This method attempts to interpret the server response and
determine whether the transaction was successful, or if an error or
exception was encountered.
@private
parameter: {object} o The connection object
parameter: {object} callback - User-defined callback object
parameter: {boolean} determines if the transaction was aborted.
returns: void
handleTransactionResponse:function(o, callback, isAbort)
{
// If no valid callback is provided, then do not process any callback handling.
if(!callback){
this.releaseObject(o);
return;
}
var httpStatus, responseObject;
try
{
if(o.conn.status !== undefined && o.conn.status != 0){
httpStatus = o.conn.status;
}
else{
httpStatus = 13030;
}
}
catch(e){
// 13030 is the custom code to indicate the condition -- in Mozilla/FF --
// when the o object's status and statusText properties are
// unavailable, and a query attempt throws an exception.
httpStatus = 13030;
}
if(httpStatus >= 200 && httpStatus < 300){
responseObject = this.createResponseObject(o, callback.argument);
if(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]);
}
}
}
else{
switch(httpStatus){
// The following case labels are wininet.dll error codes that may be encountered.
// Server timeout
case 12002:
// 12029 to 12031 correspond to dropped connections.
case 12029:
case 12030:
case 12031:
// Connection closed by server.
case 12152:
// See above comments for variable status.
case 13030:
responseObject = this.createExceptionObject(o.tId, callback.argument, isAbort);
if(callback.failure){
if(!callback.scope){
callback.failure(responseObject);
}
else{
callback.failure.apply(callback.scope, [responseObject]);
}
}
break;
default:
responseObject = this.createResponseObject(o, callback.argument);
if(callback.failure){
if(!callback.scope){
callback.failure(responseObject);
}
else{
callback.failure.apply(callback.scope, [responseObject]);
}
}
}
}
this.releaseObject(o);
},
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.
@private
parameter: {object} o The connection object
parameter: {} callbackArg User-defined argument or arguments to be passed to the callback
returns: 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;
obj.status = o.conn.status;
obj.statusText = o.conn.statusText;
obj.getResponseHeader = headerObj;
obj.getAllResponseHeaders = headerStr;
obj.responseText = o.conn.responseText;
obj.responseXML = o.conn.responseXML;
if(typeof callbackArg !== undefined){
obj.argument = callbackArg;
}
return obj;
},
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.
@private
parameter: {int} tId Transaction Id
parameter: callbackArg The user-defined arguments
parameter: isAbort Determines if the exception is an abort.
returns: 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;
},
Public method that stores the custom HTTP headers for each transaction.
@public
parameter: {string} label The HTTP header label
parameter: {string} value The HTTP header value
returns: void
initHeader:function(label,value)
{
if(this._http_header[label] === undefined){
this._http_header[label] = value;
}
else{
this._http_header[label] = value + "," + this._http_header[label];
}
this._has_http_headers = true;
},
Accessor that sets the HTTP headers for each transaction.
@private
parameter: {object} o The connection object for the transaction.
returns: void
setHeader:function(o)
{
for(var prop in this._http_header){
if(this._http_header.propertyIsEnumerable){
o.conn.setRequestHeader(prop, this._http_header[prop]);
}
}
delete this._http_header;
this._http_header = {};
this._has_http_headers = false;
},
This method assembles the form label and value pairs and
constructs an encoded string.
asyncRequest() will automatically initialize the
transaction with a HTTP header Content-Type of
application/x-www-form-urlencoded.
@public
parameter: {string || object} form id or name attribute, or form object.
parameter: {string} optional boolean to indicate SSL environment.
parameter: {string} optional qualified path of iframe resource for SSL in IE.
returns: void
setForm:function(formId, isUpload, secureUri)
{
this._sFormData = '';
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.
var oForm = (document.getElementById(formId) || document.forms[formId]);
}
else if(typeof formId == 'object'){
var 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){
(typeof secureUri == 'string')?this.createFrame(secureUri):this.createFrame();
this._isFormSubmit = true;
this._isFileUpload = true;
this._formNode = oForm;
return;
}
var oElement, oName, oValue, oDisabled;
var hasSubmit = false;
// Iterate over the form elements collection to construct the
// label-value pairs.
for (var i=0; i<oForm.elements.length; i++){
oDisabled = oForm.elements[i].disabled;
// If the name attribute is not populated, the form field's
// value will not be submitted.
oElement = oForm.elements[i];
oName = oForm.elements[i].name;
oValue = oForm.elements[i].value;
// Do not submit fields that are disabled or
// do not have a name attribute value.
if(!oDisabled && oName)
{
switch (oElement.type)
{
case 'select-one':
case 'select-multiple':
for(var j=0; j<oElement.options.length; j++){
if(oElement.options[j].selected){
this._sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oElement.options[j].value || oElement.options[j].text) + '&';
}
}
break;
case 'radio':
case 'checkbox':
if(oElement.checked){
this._sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(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){
this._sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oValue) + '&';
hasSubmit = true;
}
break;
default:
this._sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oValue) + '&';
break;
}
}
}
this._isFormSubmit = true;
this._sFormData = this._sFormData.substr(0, this._sFormData.length - 1);
},
Creates an iframe to be used for form file uploads. It is remove from the
document upon completion of the upload transaction.
@private
parameter: {string} optional qualified path of iframe resource for SSL in IE.
returns: void
createFrame:function(secureUri){
// IE does not allow the setting of id and name attributes as DOM
// properties. A different iframe creation pattern is required for IE.
if(window.ActiveXObject){
var io = document.createElement('<IFRAME name="ioFrame" id="ioFrame">');
if(secureUri){
// IE will throw a security exception in an SSL environment if the
// iframe source isn't set to a valid resource.
io.src = secureUri;
}
}
else{
var io = document.createElement('IFRAME');
io.id = 'ioFrame';
io.name = 'ioFrame';
}
io.style.position = 'absolute';
io.style.top = '-1000px';
io.style.left = '-1000px';
document.body.appendChild(io);
},
Uploads HTML form, including files/attachments, targeting the
iframe created in createFrame.
@private
parameter: {int} id The transaction id.
parameter: {object} callback - User-defined callback object.
parameter: {string} uri Fully qualified path of resource.
returns: void
uploadFile:function(id, callback, uri){
// Initialize the HTML form properties in case they are
// not defined in the HTML form.
this._formNode.action = uri;
this._formNode.enctype = 'multipart/form-data';
this._formNode.method = 'POST';
this._formNode.target = 'ioFrame';
this._formNode.submit();
// Reset form status properties.
this._formNode = null;
this._isFileUpload = false;
this._isFormSubmit = false;
// 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()
{
var oResponse =
{
tId: id,
responseText: document.getElementById("ioFrame").contentWindow.document.body.innerHTML,
argument: callback.argument
}
if(callback.upload){
if(!callback.scope){
callback.upload(oResponse);
}
else{
callback.upload.apply(callback.scope, [oResponse]);
}
}
YAHOO.util.Event.removeListener("ioFrame", "load", uploadCallback);
window.ioFrame.location.replace('#');
setTimeout("document.body.removeChild(document.getElementById('ioFrame'))",100);
};
// Bind the onload handler to the iframe to detect the file upload response.
YAHOO.util.Event.addListener("ioFrame", "load", uploadCallback);
},
Public method to terminate a transaction, if it has not reached readyState 4.
@public
parameter: {object} o The connection object returned by asyncRequest.
parameter: {object} callback User-defined callback object.
parameter: {string} isTimeout boolean to indicate if abort was a timeout.
returns: void
abort:function(o, callback, isTimeout)
{
if(this.isCallInProgress(o)){
window.clearInterval(this._poll[o.tId]);
this._poll.splice(o.tId);
if(isTimeout){
this._timeOut.splice(o.tId);
}
o.conn.abort();
this.handleTransactionResponse(o, callback, true);
return true;
}
else{
return false;
}
},
Public method to check if the transaction is still being processed.
@public
parameter: {object} o The connection object returned by asyncRequest
returns: 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.conn){
return o.conn.readyState != 4 && o.conn.readyState != 0;
}
else{
//The XHR object has been destroyed.
return false;
}
},
Dereference the XHR instance and the connection object after the transaction is completed.
@private
parameter: {object} o The connection object
returns: void
releaseObject:function(o)
{
//dereference the XHR instance.
o.conn = null;
//dereference the connection object.
o = null;
}
};
(C) Æliens
20/2/2008
You may not copy or print any of this material without explicit permission of the author or the publisher.
In case of other copyright issues, contact the author.
