ObjectOutputStream causes SocketException

[Prasanth Ravi]

I have a client-server application. Right now, I'm trying to test sending messages from the client to the server and then read them from the server.
I'm using ObjectInputStream and ObjectOutputStream to transfer message objects between the client and server.

However, when I try to write an object from the client, it results in a SocketException.

Server code:

 
      while (true) {
            try {

                log.trace("Waiting for connection.");
                Socket clientSocket = socket.accept();
                log.trace("Socket connected");
                /* create thread */
                new Thread(new RequestRunner(clientSocket, serverID)).start();


            } catch (SocketTimeoutException e) {
                log.trace("Socket timed out.");
                socket.close();
                break;
            } catch (IOException e) {
                log.error("Cannot accept connection...");
                break;
            }
        }

Server Thread:

    public class RequestRunner implements Runnable {

    ....

    public RequestRunner(Socket socket, UUID serverID) {
        client = socket;
        this.serverID = serverID;
    }

    /**
     * Start the thread for the request
     */
    public void run() {


        log.trace("Thread started for socket");

        try {
            out = new ObjectOutputStream(client.getOutputStream());
            in = new ObjectInputStream(client.getInputStream());
        } catch (IOException e) {
            log.error("Cannot intialize streams...");
            return;
        }

        while(client.isConnected()) {
        /* initialize streams */
            try {


            /* read message */

                Object obj = in.readObject(); // does not block
                MessageFrame msg = (MessageFrame) obj;
                processRequest(msg);
   
            } catch (IOException e) {

                ; // triggers everytime
                //log.error("IO error occured while trying to get input/output stream from socket");


            } catch (ClassNotFoundException e) {
                log.error("Cannot read MessageFrame");
            }
        }
    }
}

Client code:

 public void init(int port) throws IOException {

        log.trace("intializing to port " + port);
        clientID = UUID.randomUUID();
        socket = new Socket("0.0.0.0",port);
        out = new ObjectOutputStream(socket.getOutputStream());
        in = new ObjectInputStream(socket.getInputStream());
        
    }

    public void sendEcho() throws Exception {

        while(socket.isConnected()) {

            try {
                log.trace("Sending echo..");
                msg = new EchoMessage(clientID);
                curMsgID = msg.getMsgID();
                out.writeObject(msg);   // throws SocketException, socket closed
                out.flush();
                break;
            } catch (SocketException e) {
                log.error ("Cannot send echo.. socket closed.");
                break;
            } catch (IOException e) {
                continue;
            }
        }
    }

The statement out.writeObject(msg) causes a ServerSocket exception with Socket closed as the reason. And the server does not register receiving an object from in.readObject().

netstat shows the connection as established, the error occurs when I try to write the object.

What am I doing wrong ?

[Joe Ess]

I don't see anything obvious. What does the full stack trace look like?

[Henry Wong]

Prasanth Ravi wrote:
Client code:

socket = new Socket("0.0.0.0",port);

Can we assume that you are *not* actually using address "0.0.0.0", and that it is just that way for the post (to obfuscate your location)?

Henry

[Prasanth Ravi]

I am using the localhost.
I figured out the problem, it was not in the source code. It was a problem with my test code.
I forgot to mark this resolved, my bad.