/* AjaxPost(url, responseHandler) -----------------------------------------------------------------------------------------
Open a connection to the specified URL, which is intended to provide an XML message.  The specified data is sent
to the server as parameters.  This is the same as calling AjaxOpen("POST", url, toSend, responseHandler).

@param	string		url					The URL to connect to.
@param	string		toSend				The data to send to the server; must be URL encoded.
@param	function	responseHandler		The Javascript function handling server response.
------------------------------------------------------------------------------------------------------------------------ */
function AjaxPost(url, toSend, responseHandler) {
    AjaxOpen("POST", url, toSend, responseHandler);
}

/* AjaxGet(url, responseHandler) ------------------------------------------------------------------------------------------
Open a connection to the specified URL, which is intended to provide an XML message.  No other data is sent to the
server.  This is the same as calling AjaxOpen("GET", url, null, responseHandler).

@param	string		url					The URL to connect to.
@param	function	responseHandler		The Javascript function handling server response.
------------------------------------------------------------------------------------------------------------------------ */
function AjaxGet(url, responseHandler) {
    AjaxOpen("GET", url, null, responseHandler);
}

/* AjaxOpen(method, url, toSend, responseHandler) -------------------------------------------------------------------------
Open a connection to the specified URL, which is intended to respond with an XML message.

@param	string		method				The connection method; either "GET" or "POST".
@param	string		url					The URL to connect to.
@param	string		toSend				The data to send to the server; must be URL encoded.
@param	function	responseHandler		The Javascript function handling server response.
------------------------------------------------------------------------------------------------------------------------ */
function AjaxOpen(method, url, toSend, responseHandler) {
	if (window.XMLHttpRequest) {

		// browser has native support for XMLHttpRequest object
		req = new XMLHttpRequest();
	
	} else if (window.ActiveXObject) {
		
		// try XMLHTTP ActiveX (Internet Explorer) version
		req = new ActiveXObject("Microsoft.XMLHTTP");
	
	}
	
	if(req) {
		req.onreadystatechange = responseHandler;
		req.open(method, url, true);
		req.setRequestHeader("content-type","application/x-www-form-urlencoded");
		req.send(toSend);
	} else {
		alert('Your browser does not seem to support XMLHttpRequest.');
	}
}