function sessionKeepAlive() 
{
    var wRequest = new Sys.Net.WebRequest();
    wRequest.set_url("../SessionKeepAlive.aspx");
    wRequest.set_httpVerb("POST");
    wRequest.add_completed(sessionKeepAlive_Callback);
    //wRequest.set_body();
    //wRequest.get_headers()["Content-Length"] = 0;
    wRequest.invoke();
    //3 minute
    setTimeout(function() { sessionKeepAlive(); }, 3 * 60 * 1000);
}
function sessionKeepAliveStartPage() 
{
    var wRequest = new Sys.Net.WebRequest();
    wRequest.set_url("./SessionKeepAlive.aspx");
    wRequest.set_httpVerb("POST");
    wRequest.add_completed(sessionKeepAlive_Callback);
    //wRequest.set_body();
    //wRequest.get_headers()["Content-Length"] = 0;
    wRequest.invoke();
    //3 minute
    setTimeout(function() { sessionKeepAliveStartPage(); }, 3 * 60 * 1000);
}
function sessionKeepAlive_Callback(executor, eventArgs) 
{
    //alert('gribu dzivot');
    // No need to do anything, but if you are sending a value
    // from the server as an additional safety measure, then
    // you can check that here.
}