/**
* DUI.Stream: A JavaScript MXHR client
*
* Copyright (c) 2009, Digg, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of the Digg, Inc. nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* @module DUI.Stream
* @author Micah Snyder <micah@digg.com>
* @author Jordan Alperin <alpjor@digg.com>
* @description A JavaScript MXHR client
* @version 0.0.3
* @link http://github.com/digg/dui
*
*/
(function($) {
DUI.create('Stream', {
pong: null,
lastLength: 0,
streams: [],
listeners: {},
init: function() {
},
load: function(url) {
//These versions of XHR are known to work with MXHR
try { this.req = new ActiveXObject('MSXML2.XMLHTTP.6.0'); } catch(nope) {
try { this.req = new ActiveXObject('MSXML3.XMLHTTP'); } catch(nuhuh) {
try { this.req = new XMLHttpRequest(); } catch(noway) {
throw new Error('Could not find supported version of XMLHttpRequest.');
}
}
}
//These versions don't support readyState == 3 header requests
//try { this.req = new ActiveXObject('Microsoft.XMLHTTP'); } catch(err) {}
//try { this.req = new ActiveXObject('MSXML2.XMLHTTP.3.0'); } catch(err) {}
this.req.open('GET', url, true);
var _this = this;
this.req.onreadystatechange = function() {
_this.readyStateNanny.apply(_this);
}
this.req.send(null);
},
readyStateNanny: function() {
if(this.req.readyState == 3 && this.pong == null) {
var contentTypeHeader = this.req.getResponseHeader("Content-Type");
if(contentTypeHeader.indexOf("multipart/mixed") == -1) {
this.req.onreadystatechange = function() {
throw new Error('Send it as multipart/mixed, genius.');
this.req.onreadystatechange = function() {};
}.bind(this);
} else {
this.boundary = '--' + contentTypeHeader.split('"')[1];
//Start pinging
this.pong = window.setInterval(this.ping.bind(this), 15);
}
}
if(this.req.readyState == 4) {
//var contentTypeHeader = this.req.getResponseHeader("Content-Type");
//Stop the insanity!
clearInterval(this.pong);
//One last ping to clean up
this.ping();
if(typeof this.listeners.complete != 'undefined') {
var _this = this;
$.each(this.listeners.complete, function() {
this.apply(_this);
});
}
}
},
ping: function() {
var length = this.req.responseText.length;
var packet = this.req.responseText.substring(this.lastLength, length);
this.processPacket(packet);
this.lastLength = length;
},
processPacket: function(packet) {
if(packet.length < 1) return;
//I don't know if we can count on this, but it's fast as hell
var startFlag = packet.indexOf(this.boundary);
var endFlag = -1;
//Is there a startFlag?
if(startFlag > -1) {
if(typeof this.currentStream != 'undefined') {
//If there's an open stream, that's an endFlag, not a startFlag
endFlag = startFlag;
startFlag = -1;
} else {
//No open stream? Ok, valid startFlag. Let's try find an endFlag then.
endFlag = packet.indexOf(this.boundary, startFlag + this.boundary.length);
}
}
//No stream is open
if(typeof this.currentStream == 'undefined') {
//Open a stream
this.currentStream = '';
//Is there a start flag?
if(startFlag > -1) {
//Yes
//Is there an end flag?
if(endFlag > -1) {
//Yes
//Use the end flag to grab the entire payload in one swoop
var payload = packet.substring(startFlag, endFlag);
this.currentStream += payload;
//Remove the payload from this chunk
packet = packet.replace(payload, '');
this.closeCurrentStream();
//Start over on the remainder of this packet
this.processPacket(packet);
} else {
//No
//Grab from the start of the start flag to the end of the chunk
this.currentStream += packet.substr(startFlag);
//Leave this.currentStream set and wait for another packet
}
} else {
//WTF? No open stream and no start flag means someone fucked up the output
//...OR maybe they're sending garbage in front of their first payload. Weird.
//I guess just ignore it for now?
}
//Else we have an open stream
} else {
//Is there an end flag?
if(endFlag > -1) {
//Yes
//Use the end flag to grab the rest of the payload
var chunk = packet.substring(0, endFlag);
this.currentStream += chunk;
//Remove the rest of the payload from this chunk
packet = packet.replace(chunk, '');
this.closeCurrentStream();
//Start over on the remainder of this packet
this.processPacket(packet);
} else {
//No
//Put this whole packet into this.currentStream
this.currentStream += packet;
//Wait for another packet...
}
}
},
closeCurrentStream: function() {
//Write stream. Not sure if we need this
//this.streams.push(this.currentStream);
//Get mimetype
//First, ditch the boundary
this.currentStream = this.currentStream.replace(this.boundary + "\n", '');
/* The mimetype is the first line after the boundary.
Note that RFC 2046 says that there's either a mimetype here or a blank line to default to text/plain,
so if the payload starts on the line after the boundary, we'll intentionally ditch that line
because it doesn't conform to the spec. QQ more noob, L2play, etc. */
var mimeAndPayload = this.currentStream.split("\n");
var mime = mimeAndPayload.shift().split('Content-Type:', 2)[1].split(";", 1)[0].replace(' ', '');
//Better to have this null than undefined
mime = mime ? mime : null;
//Get payload
var payload = mimeAndPayload.join("\n");
//Try to fire the listeners for this mimetype
var _this = this;
if(typeof this.listeners[mime] != 'undefined') {
$.each(this.listeners[mime], function() {
this.apply(_this, [payload]);
});
}
//Set this.currentStream = null
delete this.currentStream;
},
listen: function(mime, callback) {
if(typeof this.listeners[mime] == 'undefined') {
this.listeners[mime] = [];
}
if(typeof callback != 'undefined' && callback.constructor == Function) {
this.listeners[mime].push(callback);
}
}
});
})(jQuery);
//Yep, I still use this. So what? You wanna fight about it?
Function.prototype.bind = function() {
var __method = this, object = arguments[0], args = [];
for(i = 1; i < arguments.length; i++)
args.push(arguments[i]);
return function() {
return __method.apply(object, args);
}
}
/* GLOSSARY
packet: the amount of data sent in one ping interval
payload: an entire piece of content, contained between multipart boundaries
stream: the data sent between opening and closing an XHR. depending on how you implement MHXR, that could be a while.
*/