Socket Timeout?

So I have a Server-Client application I am creating and heres my problem.

When the server disconnects, crashes, or a i shut it down (what I'm getting at, is its unexpected), the clients on the other end have no idea that the server has disappeared until sometime later.

I believe the clients find out at some point of a TimeOut but they do eventually find out. I want a creative way to check maybe every 15 seconds whether the server is still there. I've looked up and down the Socket api for methods I could use. For example, there is a method

socket.isConnected()

But even after I close my server this method returns true for some while.

Any ideas?

If you look at the java api doc for the isConnected method() it says it

Quote:

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returns true if the socket successfully connected to a server

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I'm going to assume that once the socket has connected to the server it will continue to return true.

One way would to simply send a packet and see if the server responds every 15 seconds. if it doesn't respond then something is wrong.