Java APIs

Hello java friends!

I have implemented an auction application over a TCP communication. The client's using a basis Socket and the server is multi threaded with a ServerSocket returning a Socket which is processed in a separate thread. The connection between server and client is closed automatic after each request, so another request from the client would need to be connected over a new connection. It's implemented like this for the sake of performance.

But however, I now want to implement the Observer pattern(which I'm also comfortable with). This would let the client be notified by the server if someone else overbids him in a auction. And I wonder how this could be completed?

I had a thought and it went like this. If the client would also have a ServerSocket then the server would be able to connect to it when ever he would like to notifying the client. What I like by this implementation is that the notification is done without any delay! This is obviously one way to implement it, but I wonder if someone else in here had a better idea,or if someone knew the standard implementation for a situation like this.

Thanks in regards!