var httpRequest;

function getHttpRequest () {
	try {
		// Firefox, Opera 8.0+, Safari
		httpRequest = new XMLHttpRequest();
	} catch (e) {
		// Internet Explorer
		try {
			httpRequest = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			try {
				httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {
				
				alert("Your browser does not support AJAX!");
				return false;
			}
		}
	}
	return httpRequest;
}

function httpGetRequest (httpRequest, url, callback) {
	httpRequest.onreadystatechange = callback;
	httpRequest.open("GET", url, true);
	httpRequest.send(null);
}

function httpPostRequest (httpRequest, url, parameters, callback) {
	httpRequest.onreadystatechange = callback;
	httpRequest.open('POST', url, true);
	httpRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	httpRequest.setRequestHeader("Content-length", parameters.length);
	httpRequest.setRequestHeader("Connection", "close");
	httpRequest.send(parameters);
}