/**
* HTTP communications module.
* @module io
*/
/**
* The io class is a utility that brokers HTTP requests through a simplified
* interface. Specifically, it allows JavaScript to make HTTP requests to
* a resource without a page reload. The underlying transport for making
* same-domain requests is the XMLHttpRequest object. YUI.io can also use
* Flash, if specified as a transport, for cross-domain requests.
*
* @class io
*/
/**
* Base IO functionality. Provides basic XHR transport support
* @module io
* @submodule io-base
*/
/**
* @event io:start
* @description This event is fired by YUI.io when a transaction is initiated..
* @type Event Custom
*/
var E_START = 'io:start',
/**
* @event io:complete
* @description This event is fired by YUI.io when a transaction is complete and
* all response data are available.
* @type Event Custom
*/
E_COMPLETE = 'io:complete',
/**
* @event io:success
* @description This event is fired by YUI.io when a transaction is complete and
* the HTTP status resolves to HTTP2xx.
* @type Event Custom
*/
E_SUCCESS = 'io:success',
/**
* @event io:failure
* @description This event is fired by YUI.io when a transaction is complete and
* the HTTP status resolves to HTTP4xx, 5xx and above.
* @type Event Custom
*/
E_FAILURE = 'io:failure',
/**
* @event io:abort
* @description This event is fired by YUI.io when a transaction is aborted
* explicitly or by a defined config.timeout.
* @type Event Custom
*/
E_ABORT = 'io:abort',
//--------------------------------------
// Properties
//--------------------------------------
/**
* @description A transaction counter that increments for each transaction.
*
* @property transactionId
* @private
* @static
* @type int
*/
transactionId = 0,
/**
* @description Object of default HTTP headers to be initialized and sent
* for all transactions.
*
* @property _headers
* @private
* @static
* @type object
*/
_headers = {
'X-Requested-With' : 'XMLHttpRequest'
},
/**
* @description Object that stores timeout values for any transaction with
* a defined "timeout" configuration property.
*
* @property _timeOut
* @private
* @static
* @type object
*/
_timeout = {};
//--------------------------------------
// Methods
//--------------------------------------
// Window reference
w = Y.config.win;
/**
* @description Method for requesting a transaction. _io() is implemented as
* yui.io(). Each transaction may include a configuration object. Its
* properties are:
*
* method: HTTP method verb (e.g., GET or POST). If this property is not
* not defined, the default value will be GET.
*
* data: This is the name-value string that will be sent as the transaction
* data. If the request is HTTP GET, the data become part of
* querystring. If HTTP POST, the data are sent in the message body.
*
* xdr: Defines the transport to be used for cross-domain requests. By
* setting this property, the transaction will use the specified
* transport instead of XMLHttpRequest. Currently, the only alternate
* transport supported is Flash (e.g., { xdr: 'flash' }).
*
* form: This is a defined object used to process HTML form as data. The
* properties are:
* {
* id: object, //HTML form object or id of HTML form
* useDisabled: boolean, //Allow disabled HTML form field values
* to be sent as part of the data.
* }
*
* on: This is a defined object used to create and handle specific
* events during a transaction lifecycle. These events will fire in
* addition to the global io events. The events are:
* start - This event is fired when a request is sent to a resource.
* complete - This event fires when the transaction is complete.
* success - This event fires when the response status resolves to
* HTTP 2xx.
* failure - This event fires when the response status resolves to
* HTTP 4xx, 5xx, and beyond.
* abort - This even is fired when a transaction abort is fire by
* timeout, or when it is manually aborted.
*
* The properties are:
* {
* start: function(id, args){},
* complete: function(id, responseobject, args){},
* success: function(id, responseobject, args){},
* failure: function(id, responseobject, args){},
* abort: function(id, args){}
* }
* Each property can reference a function or be written as an
* inline function.
*
* context: Object reference for an event handler when it is implemented
* as a method of a base object. Defining "context" will preserve
* the proper reference of "this" used in the event handler.
* headers: This is a defined object of client headers, as many as.
* desired for the transaction. These headers are sentThe object
* pattern is:
* {
* header: value
* }
*
* timeout: This value, defined as milliseconds, is a time threshold for the
* transaction. When this threshold is reached, and the transaction's
* Complete event has not yet fired, the transaction will be aborted.
* arguments: Object, array, string, or number passed to all registered
* event handlers. This value is available as the second
* argument in the "start" and "abort" event handlers; and, it is
* the third argument in the "complete", "success", and "failure"
* event handlers.
*
* @method _io
* @private
* @static
* @param {string} uri - qualified path to transaction resource.
* @param {object} c - configuration object for the transaction.
* @return object
*/
function _io(uri, c) {
var c = c || {},
o = _create((arguments.length === 3) ? arguments[2] : null, c),
m = (c.method) ? c.method.toUpperCase() : 'GET',
d = (c.data) ? c.data : null,
f;
/* Determine configuration properties */
// If config.form is defined, perform data operations.
if (c.form) {
if (c.form.upload) {
u = Y.io._upload(o, uri, c);
return u;
}
// Serialize the HTML form into a string of name-value pairs.
f = Y.io._serialize(c.form);
// If config.data is defined, concatenate the data to the form string.
if (d) {
f += "&" + d;
Y.log('Configuration object.data added to serialized HTML form data. The string is: ' + f, 'info', 'io');
}
if (m === 'POST') {
d = f;
_setHeader('Content-Type', 'application/x-www-form-urlencoded');
}
else if (m === 'GET') {
uri = _concat(uri, f);
Y.log('Configuration object.data added to serialized HTML form data. The querystring is: ' + uri, 'info', 'io');
}
}
else if (d && m === 'GET') {
uri = _concat(uri, c.data);
Y.log('Configuration object data added to URI. The querystring is: ' + uri, 'info', 'io');
}
else if (d && m === 'POST') {
_setHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');
}
if (c.xdr) {
Y.io._xdr(uri, o, c);
return o;
}
// If config.timeout is defined, and the request is standard XHR,
// initialize timeout polling.
if (c.timeout) {
_startTimeout(o, c);
}
/* End Configuration Properties */
o.c.onreadystatechange = function() { _readyState(o, c); };
try {
_open(o.c, m, uri);
}
catch (e) {
}
_setHeaders(o.c, (c.headers || {}));
o.abort = function () {
_ioAbort(o, c);
}
o.isInProgress = function() {
return o.c.readyState !== 4 && o.c.readyState !== 0;
}
// Do not pass null, in the absence of data, as this
// will result in a POST request with no Content-Length
// defined.
_async(o, (d || ''), c);
return o;
};
/**
* @description Method for creating and subscribing transaction events.
*
* @method _tPubSub
* @private
* @static
* @param {string} e - event to be published
* @param {object} c - configuration object for the transaction.
*
* @return void
*/
function _tPubSub(e, c){
var event = new Y.Event.Target().publish('transaction:' + e);
event.subscribe(c.on[e], (c.context || this), c.arguments);
return event;
};
/**
* @description Fires event "io:start" and creates, fires a
* transaction-specific start event, if config.on.start is
* defined.
*
* @method _ioStart
* @private
* @static
* @param {number} id - transaction id
* @param {object} c - configuration object for the transaction.
*
* @return void
*/
function _ioStart(id, c) {
// Set default value of argument c, property "on" to Object if
// the property is null or undefined.
c.on = c.on || {};
var m = Y.io._fn || {},
fn = (m && m[id]) ? m[id] : null,
event;
if (fn) {
c.on.start = fn.start;
delete fn;
}
Y.fire(E_START, id);
if (c.on.start) {
event = _tPubSub('start', c);
event.fire(id);
}
Y.log('Transaction ' + id + ' started.', 'info', 'io');
};
/**
* @description Fires event "io:complete" and creates, fires a
* transaction-specific "complete" event, if config.on.complete is
* defined.
*
* @method _ioComplete
* @private
* @static
* @param {object} o - transaction object.
* @param {object} c - configuration object for the transaction.
*
* @return void
*/
function _ioComplete(o, c) {
// Set default value of argument c, property "on" to Object if
// the property is null or undefined.
c.on = c.on || {};
var event;
Y.fire(E_COMPLETE, o.id, o.c);
if (c.on.complete) {
event = _tPubSub('complete', c);
event.fire(o.id, o.c);
}
Y.log('Transaction ' + o.id + ' completed.', 'info', 'io');
}
/**
* @description Fires event "io:success" and creates, fires a
* transaction-specific "success" event, if config.on.success is
* defined.
*
* @method _ioSuccess
* @private
* @static
* @param {object} o - transaction object.
* @param {object} c - configuration object for the transaction.
*
* @return void
*/
function _ioSuccess(o, c) {
// Set default value of argument c, property "on" to Object if
// the property is null or undefined.
c.on = c.on || {};
var m = Y.io._fn || {},
fn = (m && m[o.id]) ? m[o.id] : null,
event;
if (fn) {
c.on.success = fn.success;
delete fn;
//Decode the response from IO.swf
o.c.responseText = decodeURI(o.c.responseText);
}
Y.fire(E_SUCCESS, o.id, o.c);
if (c.on.success) {
event = _tPubSub('success', c);
event.fire(o.id, o.c);
}
_destroy(o, (c.xdr) ? true : false );
Y.log('HTTP Status evaluates to Success. The transaction is: ' + o.id, 'info', 'io');
}
/**
* @description Fires event "io:failure" and creates, fires a
* transaction-specific "failure" event, if config.on.failure is
* defined.
*
* @method _ioFailure
* @private
* @static
* @param {object} o - transaction object.
* @param {object} c - configuration object for the transaction.
*
* @return void
*/
function _ioFailure(o, c) {
// Set default value of argument c, property "on" to Object if
// the property is null or undefined.
c.on = c.on || {};
var m = Y.io._fn || {},
fn = (m && m[o.id]) ? m[o.id] : null,
event;
if (fn) {
c.on.failure = fn.failure;
delete fn;
//Decode the response from IO.swf
o.c.responseText = decodeURI(o.c.responseText);
}
Y.fire(E_FAILURE, o.id, o.c);
if (c.on.failure) {
event = _tPubSub('failure', c);
event.fire(o.id, o.c);
}
_destroy(o, (c.xdr) ? true : false );
Y.log('HTTP Status evaluates to Failure. The transaction is: ' + o.id, 'info', 'io');
}
/**
* @description Fires event "io:abort" and creates, fires a
* transaction-specific "abort" event, if config.on.abort is
* defined.
*
* @method _ioAbort
* @private
* @static
* @param {object} o - Transaction object generated by _create().
* @param {object} c - Configuration object passed to YUI.io().
*
* @return void
*/
function _ioAbort(o, c) {
// Set default value of argument c, property "on" to Object if
// the property is null or undefined.
c.on = c.on || {};
var m = Y.io._fn || {},
fn = (m && m[o.id]) ? m[o.id] : null,
event;
if(o && o.c && !c.xdr) {
// Terminate the transaction
o.c.abort();
if (c) {
// Clear the timeout poll for this specific transaction.
if (c.timeout) {
_clearTimeout(o.id);
}
}
}
if (fn) {
c.on.abort = fn.abort;
delete fn;
}
Y.fire(E_ABORT, o.id);
if (c.on.abort) {
event = _tPubSub('abort', c);
event.fire(id);
}
_destroy(o, (c.xdr) ? true : false );
Y.log('Transaction timeout or explicit abort. The transaction is: ' + o.id, 'info', 'io');
}
/**
* @description Method that increments _transactionId for each transaction.
*
* @method _id
* @private
* @static
* @return int
*/
function _id() {
var id = transactionId;
transactionId++;
Y.log('Transaction id generated. The id is: ' + id, 'info', 'io');
return id;
};
/**
* @description Method that creates a unique transaction object for each
* request..
*
* @method _create
* @private
* @static
* @param {number} s - URI or root data.
* @param {number} c - configuration object
* @return object
*/
function _create(i, c) {
var o = {};
o.id = Y.Lang.isNumber(i) ? i : _id();
if (c.xdr) {
o.c = Y.io._transportMap[c.xdr.use];
}
else if (c.form && c.form.upload) {
o.c = {};
}
else {
o.c = _xhr();
}
return o;
};
/**
* @description Method that creates the XMLHttpRequest transport
*
* @method _xhr
* @private
* @static
* @return object
*/
function _xhr() {
return (w.XMLHttpRequest) ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHTTP');
};
/**
* @description Method that concatenates string data for HTTP GET transactions.
*
* @method _concat
* @private
* @static
* @param {string} s - URI or root data.
* @param {string} d - data to be concatenated onto URI.
* @return int
*/
function _concat(s, d) {
s += ((s.indexOf('?') == -1) ? '?' : '&') + d;
return s;
};
/**
* @description Method that stores default client headers for all transactions.
* If a label is passed with no value argument, the header will be deleted.
*
* @method _setHeader
* @private
* @static
* @param {string} l - HTTP header
* @param {string} v - HTTP header value
* @return int
*/
function _setHeader(l, v) {
if (v) {
_headers[l] = v;
}
else {
delete _headers[l];
}
};
/**
* @description Method that sets all HTTP headers to be sent in a transaction.
*
* @method _setHeaders
* @private
* @static
* @param {object} o - XHR instance for the specific transaction.
* @param {object} h - HTTP headers for the specific transaction, as defined
* in the configuration object passed to YUI.io().
* @return void
*/
function _setHeaders(o, h) {
var p;
for (p in _headers) {
if (_headers.hasOwnProperty(p)) {
if (h[p]) {
// Configuration headers will supersede IO preset headers,
// if headers match.
Y.log('Matching configuration HTTP header: ' + p + ' found with value of ' + _headers[p], 'info', 'io');
break;
}
else {
h[p] = _headers[p];
Y.log('HTTP header ' + p + ' found with value of ' + _headers[p], 'info', 'io');
}
}
}
for (p in h) {
if (h.hasOwnProperty(p)) {
o.setRequestHeader(p, h[p]);
Y.log('HTTP Header ' + p + ' set with value of ' + h[p], 'info', 'io');
}
}
};
function _open(o, m, uri) {
o.open(m, uri, true);
};
/**
* @description Method that sends the transaction request.
*
* @method _async
* @private
* @static
* @param {object} o - Transaction object generated by _create().
* @param {string} d - Transaction data.
* @param {object} c - Configuration object passed to YUI.io().
* @return void
*/
function _async(o, d, c) {
o.c.send(d);
_ioStart(o.id, c);
};
/**
* @description Starts timeout count if the configuration object
* has a defined timeout property.
*
* @method _startTimeout
* @private
* @static
* @param {object} o - Transaction object generated by _create().
* @param {object} c - Configuration object passed to YUI.io().
* @return void
*/
function _startTimeout(o, c) {
_timeout[o.id] = w.setTimeout(function() { _ioAbort(o, c); }, c.timeout);
};
/**
* @description Clears the timeout interval started by _startTimeout().
*
* @method _clearTimeout
* @private
* @static
* @param {number} id - Transaction id.
* @return void
*/
function _clearTimeout(id) {
w.clearTimeout(_timeout[id]);
delete _timeout[id];
};
/**
* @description Event handler bound to onreadystatechange.
*
* @method _readyState
* @private
* @static
* @param {object} o - Transaction object generated by _create().
* @param {object} c - Configuration object passed to YUI.io().
* @return void
*/
function _readyState(o, c) {
if (o.c.readyState === 4) {
if (c.timeout) {
_clearTimeout(o.id);
}
_ioComplete(o, c);
_handleResponse(o, c);
}
};
/**
* @description Method that determines if a transaction response qualifies
* as success or failure, based on the response HTTP status code, and
* fires the appropriate success or failure events.
*
* @method _handleResponse
* @private
* @static
* @param {object} o - Transaction object generated by _create().
* @param {object} c - Configuration object passed to io().
* @return void
*/
function _handleResponse(o, c) {
var status;
try{
if (o.c.status && o.c.status !== 0) {
status = o.c.status;
}
else {
status = 0;
}
}
catch(e) {
status = 0;
Y.log('HTTP status unreadable. The transaction is: ' + o.id, 'warn', 'io');
}
/*
* IE reports HTTP 204 as HTTP 1223.
* However, the response data are still available.
*
* setTimeout() is used to prevent transactions from becoming
* synchronous, in IE, when the response data are read from cache
* (e.g., HTTP 304).
*/
if (status >= 200 && status < 300 || status === 1223) {
w.setTimeout( function() { _ioSuccess(o, c); }, 0);
}
else {
w.setTimeout( function() {_ioFailure(o, c); }, 0);
}
};
function _destroy(o, isTransport) {
// IE6 will throw a "Type Mismatch" error if the event handler is set to "null".
if(w.XMLHttpRequest && !isTransport) {
if (o.c) {
o.c.onreadystatechange = null;
}
}
o.c = null;
o = null;
};
_io.start = _ioStart;
_io.complete = _ioComplete;
_io.success = _ioSuccess;
_io.failure = _ioFailure;
_io.abort = _ioAbort;
_io._id = _id;
_io._timeout = _timeout;
//--------------------------------------
// Begin public interface definition
//--------------------------------------
/**
* @description Method that stores default client headers for all transactions.
* If a label is passed with no value argument, the header will be deleted.
* This is the interface for _setHeader().
*
* @method header
* @public
* @static
* @param {string} l - HTTP header
* @param {string} v - HTTP header value
* @return int
*/
_io.header = _setHeader;
/**
* @description Method for requesting a transaction. This
* is the interface for _io().
*
* @method io
* @public
* @static
* @param {string} uri - qualified path to transaction resource.
* @param {object} c - configuration object for the transaction.
* @return object
*/
Y.io = _io;