function create_subscriber(topic_name) 
{
    body = "<?xml version=\"1.0\"?><subscription>"+
	"<domainId>" + domain_id + "</domainId>" + 
	"<topicName>"+ topic_name + "</topicName>" + 
	"<typeName>" + type_name + "</typeName>" + 
	"<typeSchema>" + type_schema + "</typeSchema>" +
	"<qosProfile>" + qos_profile + "</qosProfile>" + 
	"<contentFilterExpression>" + "</contentFilterExpression>" +
	"<encodingStyle>1</encodingStyle>" + 
	"</subscription>";	

    subscriber_id[topic_name] = -1;

    var url = "/wsdds/" + dds_sessionid + "/subscription";
    var xmlhttp = newAjax();

    xmlhttp.onreadystatechange = function() {
	if (xmlhttp.readyState == 4) {
	    var xmlResponse = xmlhttp.responseXML;

	    if(xmlResponse.getElementsByTagName("returnCode")[0].childNodes[0].nodeValue !="0"){
		alert(xmlResponse.getElementsByTagName("returnString")[0].childNodes[0].nodeValue+". Please, login again.");
	    }
	    else{
		subscriber_id[topic_name] = xmlResponse.getElementsByTagName("subscriptionId")[0].childNodes[0].nodeValue;
		read(topic_name);
	    }
	}
    };

    xmlhttp.open('PUT', url, true);
    xmlhttp.setRequestHeader("Content-type", "text/xml");
    xmlhttp.send(body);
    
};

function read(topic_name)
{
    if(subscriber_id[topic_name] == -1) {
	return;
    }

    url = "/wsdds/" + dds_sessionid +
	"/subscription/" +
	subscriber_id[topic_name] + "/15/";


    var xmlhttp = newAjax();
    xmlhttp.onreadystatechange = function() {
	if (xmlhttp.readyState == 4) {
	    var xmlResponse = xmlhttp.responseXML;
	    var samples = xmlResponse.getElementsByTagName("sample");
	    
	    for(i=0; i<samples.length; i++) {
		if(samples[i].getElementsByTagName("validData")[0].childNodes[0].nodeValue) {
		    //Do something
		}
	    }

	    timeouts[topic_name] = setTimeout("read(\""+ topic_name +"\")",500);
	}
    }


    xmlhttp.open('GET', url, true);
    xmlhttp.setRequestHeader("Content-type", "text/xml");
    xmlhttp.send("");

}

function delete_subscriber(topic_name)
{
    url = "/wsdds/" +
	dds_sessionid  +
        "/subscription/" +
	subscriber_id[topic_name];
    
    
    var xmlhttp = newAjax();
    xmlhttp.onreadystatechange = function() {
	if (xmlhttp.readyState == 4) {
	    var xmlResponse = xmlhttp.responseXML;

	    
	    if (xmlResponse.getElementsByTagName("returnCode")[0].childNodes[0].nodeValue != "0"){
		return;
	    }
            else {
                subscriber_id[topic_name] = -1;
                clearTimeout(timeouts[topic_name]);
                delete timeouts[topic_name];
                return;

            }
        }
    };
    
    xmlhttp.open('DELETE', url, true);
    xmlhttp.setRequestHeader("Content-type", "text/xml");
    xmlhttp.send("");
    
}