Applet connecting to server

I don't know very much about networking or applets. Basically, I need a way for the server to send information to the browser outside of a response to an HTTPrequest; I don't want to have to continually poll the server using AJAX.

My question is: can an applet always open a socket to the host on which they were loaded? With s = new Socket( this.getCodeBase().getHost() ) , that is?

Nothing else I have to do? No security problems or firewalls or anything to worry about?

Any help is very much appreciated.

In general, an Applet talk to server from which it came with remarkably few issues.