var HttpRequest = { 
	xmlhttp : null,
	setHttpRequest : function() {
		if (this.xmlhttp != null) {
			return;
		}
		
		if (window.XMLHttpRequest)
		{
			/* code for IE7+, Firefox, Chrome, Opera, Safari */
			this.xmlhttp=new XMLHttpRequest();
		}
		else if (window.ActiveXObject)
		{
			/* code for IE6, IE5 */
			this.xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
		}
		else
		{
			this.xmlhttp=null;
		}	
	}
}