Java socket second write attempt fails

I have a function:

...
socket.getOutputStream().write("something".getBytes());
socket.getOutputStream().flush();
...

Works fine. Keep socket open. Trying to call this function again but get the error: java.net.SocketExce开发者_高级运维ption: Broken pipe

despite the fact that

socket.isClosed - false

socket.isOutputShutdown - false

socket.isConnected - true

It is most likely the other end has closed the connection. It is possible the first write failed as well, as write() does not guarenteed delivery. You only get an Exception once it knows the other end is not listening.

isClosed means; have I closed the connection

isOutputShutdown means; have I shutdown the output

isConnected means; has it ever connected

The only way to detect that a connection is truly up is to get a response from the other end telling you it has received your data. e.g. a response to a heartbeat. Without that response (which must be part of your protocol) you cannot be sure the other end has received it.

Broken pipe means that you wrote data to a connection that had already been closed by the other end. This can indicate an application protocol error.