Ping utility

gistfile1.java

// Server loop
...
    accepted = serverSocket.accept();
    accepted.socket().setTcpNoDelay(true);
    accepted.configureBlocking(false);
    serverSocket.close();
    while (!Thread.interrupted()) {
        buffy.clear();
        do {
            if (accepted.read(buffy) == -1)
                return;
        } while (buffy.position() == 0);
        buffy.flip();
        accepted.write(buffy);
    }

// Client loop
...
    bb.position(0);
    bb.limit(messageSize);
    do {
        sc.write(bb);
    } while (bb.hasRemaining());
    
    // receive
    bb.clear();
    int bytesRead = 0;
    do {
        bytesRead += sc.read(bb);
    } while (bytesRead < messageSize);