sending packets of data

js#PacketSender.js

var PacketSender = function (url, options) {
	this.data = [];
	this.url = url;
	options = options || {};
	if (!options.maxPacketsToSend)
		options.maxPacketsToSend = 100;
	if (!options.timeout)
		options.timeout = 60000;
	this.o = options;
	this.queuedPackets = {};
}

PacketSender.prototype.addPacket = function (packet) {
	this.data.push (packet);
};

PacketSender.prototype.onReadyStateChange = function(requestId, evt) {
	var req = evt.target;

	if (req.readyState == 4) {
		if (req.status == 200)
			delete this.queuedPackets[requestId];
		// alert(req.responseText);
		else if (req.status) {
			this.onError(requestId, evt);
		}
		//alert("Error loading page\n");
	}
}

PacketSender.prototype.onError = function (requestId, evt) {
	console.log(requestId, evt);
	var failedPackets = this.queuedPackets[requestId];
	delete this.queuedPackets[requestId]
		//this.data.unshift.apply (failedPackets);
		this.data.unshift.apply(this.data, failedPackets);
	}


	PacketSender.prototype.createXHR = function (method, url) {

	if (!url && method) {
		url	 = method;
		method = "GET";
	}

	var xhr = new XMLHttpRequest();
		//xhr.onload = reqListener;

		xhr.open("POST", url, true);
		//xhr.setRequestHeader("Authorization", "Basic " + btoa(username + ":" + password));
		//xhr.send(JSON.stringify (kinectDataForReq));

		return xhr;
	};

	PacketSender.prototype.sendPackets = function (xhr, timeout) {

	var self = this;

	if (this.o.noEmptyRequest && this.data.length == 0) {
		console.log ('no data to send');
		return;
	}

	if (!xhr) {
		if (this.url) {
			xhr = this.createXHR (this.method, this.url);
		} else {
			console.error ('you must provide existing xhr object or url to sendPackets '
				+'or define url via constructor new PacketSender (url, {"maxPacketsToSend": 100})');
		}
	} else if (xhr instanceof XMLHttpRequest) {
	} else if (("string" == typeof xhr) || (xhr instanceof String)) {
		var url = xhr;
		xhr = this.createXHR (arguments);
	}

	var packetsToSend = this.data.splice (0, (
		this.o.maxPacketsToSend > this.data.length
		? this.data.length
		: this.o.maxPacketsToSend
		));

	var requestId = new Date().getTime();
		// TODO: check for overwrite
		this.queuedPackets[requestId] = packetsToSend;

		if (this.o.dataWrapper && typeof this.o.dataWrapper === "function") {
		packetsToSend = this.o.dataWrapper (packetsToSend);
		}

		if (this.o.xhrWrapper && typeof this.o.xhrWrapper === "function") {
		this.o.xhrWrapper (xhr);
		}

		xhr.timeout = this.timeout || timeout;

		xhr.addEventListener ("error", this.onError.bind (this, requestId), false);
		xhr.ontimeout = this.onError.bind (this, requestId);
		xhr.onreadystatechange = this.onReadyStateChange.bind (this, requestId);
		xhr.send(JSON.stringify (packetsToSend));

	};

usage-example.js

 var options = {
  maxPacketsToSend: 10,
  xhrWrapper: function(oReq) {
   //var username = "kinect";
   //var password = "sdlkg3";
   var username = "hack";
   var password = "thegibson";

   oReq.setRequestHeader("Authorization", "Basic " + btoa(username + ":" + password));
  }
 };

 var packetSender = new PacketSender('http://apla.me:5000', options);

 for (i = 0; i < 100; i++) {
  packetSender.addPacket({id: i});
 }

 timer = setInterval(function() {
  packetSender.sendPackets();
  if (!packetSender.data.length)
   clearInterval(timer);
 }, 2000);