function TXmlHttp()
{
	this.xmlHttp;
	
	// check for browser and use the proper XmlHttpRequest object
	if(window.XMLHttpRequest)
		this.xmlHttp = new XMLHttpRequest();
    else if(window.ActiveXObject)
    {
		try
		{
			this.xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
      	}
      	catch(e)
      	{
      		try
      		{
      			this.xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
      		}
      		catch(ex)
      		{
      			alert("no xmlhttp object available");
      			return null;
      		}
		}
    }
	
	return this.xmlHttp;
}