jQuery check server updates in a setInterval function - what else can be used?

I want to create the code which will check if e.g some new muser messages appeared and show its count. I know it's simple - just make an ajax calls in the setInterval function:

$(document).ready(function () {

    setInterval(function () {
        //create an ajax call
    }, 30000);

});

but it's not the point - I can't find any information of the other approaches. Is it the only way to achieve this by set the setInterval function to check the updates ?

Edit

Ok, I've found http://socket.io/ maybe it's what I'm looking for