function HttpClient() {}

HttpClient.prototype = {
	// type GET, POST passed to open
	requestType:'GET',
	// when set to true, async calls are made
	isAsync:false,
	// where an XMLHttpRequest instance is stored
	xmlhttp:false,
	//what is called when a successful async call is made
	callback:false,
	// what is called when send is called on HTMLHttpRequest
	onSend:function() {
		document.getElementById('HttpClientStatus').style.display = 'block';
	},
	
	//what is called when readystate 4 is reached
	onLoad:function() {
		document.getElementById('HttpClientStatus').style.display = 'none';
	},
	onError:function(error) {
		alert(error);
	},
	
	init:function() {
		try {
			//mozilla / Safari
			this.xmlhttp = new XMLHttpRequest();
		} catch (e) {
			// IE
			var XMLHTTP_IDS = new Array('MSXML2.XMLHTTP.5.0',
								   'MSXML2.XMLHTTP.4.0',
								   'MSXML2.XMLHTTP.3.0',
								   'MSXML2.XMLHTTP',
								   'Microsoft.XMLHTTP'
								   );
			var success = false;
			for (var i=0; i < XMLHTTP_IDS.length && !success; i++) {
				try {
					this.xmlhttp = new ActiveXObject(XMLHTTP_IDS[i]);
					success = true;
				} catch (e) {}
			}
			if (!success) {
				this.onError('Unable to create XMLHttpRequest');
			}
		}
	},
	
	makeRequest: function(url, payload) {
		if (!this.xmlhttp) {
			this.init();
		}
		this.xmlhttp.open(this.requestType, url, this.isAsync);
		
		var self = this;
		this.xmlhttp.onreadystatechange = function() {
			self._readyStateChangeCallback();
		}
		
		this.xmlhttp.send(payload);
		
		if (!this.isAsync) {
			return this.xmlhttp.responseText;
		}
	},
	
	_readyStateChangeCallback:function() {
		switch(this.xmlhttp.readyState) {
			case 2:
				this.onSend();
			break;
			
			case 4:
				this.onLoad();
				if (this.xmlhttp.status == 200) {
					this.callback(this.xmlhttp.responseText);
				} else {
					this.onError('HTTP Error making Request: ' + 
							   '[' + this.xmlhttp.status + ']' +
							   this.xmlhttp.statusText);
				}
			break;
		}
	}
}