//Global XMLHTTP Request object
var XmlHttp;
var contextValue = "";
//Creating and setting the instance of appropriate XMLHTTP Request object to a “XmlHttp” variable  
function CreateXmlHttp()
{
	//Creating object of XMLHTTP in IE
	try
	{
		XmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
	}
	catch(e)
	{
		try
		{
			XmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
		} 
		catch(oc)
		{
			XmlHttp = null;
		}
	}
	//Creating object of XMLHTTP in Mozilla and Safari 
	if(!XmlHttp && typeof XMLHttpRequest != "undefined") 
	{
		XmlHttp = new XMLHttpRequest();
	}
}


function RunAjax(requestPage, URLString, method, contextTxt) 
{
	contextValue = contextTxt;
	var requestUrl = "http://" + location.host + "/" + requestPage + "?" + URLString;
	
	CreateXmlHttp();
	// If browser supports XMLHTTPRequest object
	if(XmlHttp)
	{
		//Setting the event handler for the response
		XmlHttp.onreadystatechange = HandleResponse;
		
		//Initializes the request object, 
		//Request URL and sets the request as asynchronous.
		XmlHttp.open(method, requestUrl,  true);
		
		//Sends the request to server
		XmlHttp.send(null);		
	}
}


//Called when response comes back from server
function HandleResponse()
{
	// To make sure receiving response data from server is completed
	if(XmlHttp.readyState == 4)
	{
		// To make sure valid response is received from the server, 200 means response received is OK
		if(XmlHttp.status == 200)
		{			
			Handle(XmlHttp.responseText, contextValue);
		}
		else
		{
			alert("There was a problem retrieving data from the server." );
		}
		
	}
}