var isIE = false;

function read_url(script, query, func) {
	var req = false;
	// llama XMLHttpRequest objecto 
	if (window.XMLHttpRequest) {
		req = new XMLHttpRequest();
		if (req.overrideMimeType) {
			req.overrideMimeType('text/xml');          
		}
		// Si no funciona intenta utilizar el objeto IE/Windows ActiveX 
		} else {
			if (window.ActiveXObject) {
				isIE = true;
				req = new ActiveXObject("Microsoft.XMLHTTP");    
			}
		}
	
	if(req){
		req.onreadystatechange = function() {
			var response;
			// only if req shows "loaded"
			if (req.readyState == 4) {
				if (req.status == 200) {
					func(req.responseText);			
				} else {
					alert("Hubo un Error tratando de leer los datos:\n" +	req.statusText);
				}
			}
		}
		req.open('POST', script + '.pl', false);
		req.setRequestHeader('Content-type', 'application/x-www-form-urlencoded;');
		req.send(query);
	}	
}