How do you determine when a client has closed its socket, so that aserver can cease to wait for messages from that client?
When a socket endpoint closes its socket, a read on the InputStreamat the other end will return -1, indicating end of file. If theprocess crashes, the same will happen because the operating systemwill close the socket when the process dies.
However, if the hostthat the process is running on crashes, there is no way to detectthe endpoint termination. With native system programming, it ispossible to set the SO_KEEPALIVE socket option to test the integrityof a connection on a more frequent basis than the default 2 hours.Java does not allow you to do this, and instead relies on the systemdefault.