Question

What is the efficient way of blocking on the socket for data after opening it.The method i used is to call read on input stream (this is a blocking call that waits till some data written to this socket).

//Socket creation
SocketForCommunication = new Socket();
InetSocketAddress sAddr = new InetSocketAddress("hostName", 8800);
SocketForCommunication.connect(sAddr,10000);
is = new DataInputStream(SocketForCommunication.getInputStream());
os = new DataOutputStream(SocketForCommunication.getOutputStream());

//Waiting on socket using read method for data
while(true)
{
    int data = is.read();
    if(data == HEADER_START)
    {
        processPackage(is);
    }
}

Here problem is read can timeout.Is there a way to register a callback that gets called when data available to read on socket.?

Answer 1

The socket will timeout by default, but you can change this if you really want to. See the Socket.setSoTimeout() call (a timeout of zero means “indefinite”).

N.B. Even if you specify a zero timeout, your O/S may or may not actually let you keep a socket open indefinitely. For example, idle sockets may get closed after a certain amount of time. In environments, e.g. shared web hosting environments, it’s not uncommon for a housekeeping routine to also run (say) once a day and shut down idle sockets.

And of course, stuff happens on networks. Either way, you shouldn’t rely on the socket staying open indefinitely…