CODEWITHSUNDEEP
javasocketsexception
Guillaume
Guillaume

Reputation: 5555

how to know a Java Socket is dead

I use a Java Socket object in my client application. I need to know when the line to the server is broken, or if any event caused the socket to be dead.

I see two methods:

Does any of these methods guarantee I'll know when the socket is dead and won't work again, even if a temporary problem on the line is solved? Can we except a (Socket)Exception thrown during an operation on a socket to imply the socket is dead?

Is there a better method to know this?

Upvotes: 3

Views: 1706

Answers (4)

stacker
stacker

Reputation: 68942

Since there is nothing like a keep-alive between sockets, you will learn that the connection is broken not until ,next time you try to write onto this socket.

Upvotes: 0

penpen
penpen

Reputation: 730

At least:

  1. Receiving an exception does NOT mean the socket is always dead, from Socket.setSoTimeout() javadoc:

    If the timeout expires [on a read for instance, a java.net.SocketTimeoutException is raised, though the Socket is still valid.

  2. The closed flag of the socket seems to be set only when the Socket.close() method is called, so I would not rely on it.

Upvotes: 2

cafebabe
cafebabe

Reputation: 1400

This is usually done by a timeout. This is mandatory if you don't trust the other side (like every time). Without a timeout, an attacker can DoS your application easily by opening connections without sending anything. Once you hit the socket limit of your system, the application might even crash...

Upvotes: 1

Chathuranga Chandrasekara
Chathuranga Chandrasekara

Reputation: 20906

A "Dead Socket" can be considered as an abnormal status. It is just a errornous bahaviour. So I don't think you can handle this situation effectively.

Upvotes: 0

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