MINA: Performing synchronous write requests / read responses

I'm attempting to perform a synchronous write/read in a demux-based client application with MINA 2.0 RC1, but it seems to get stuck. Here is my code:

public boolean login(final String username, final String password) {
    // block inbound messages
    session.getConfig().setUseReadOperation(true);

    // send the login request
    final LoginRequest loginRequest = new LoginRequest(username, password);
    final WriteFuture writeFuture = session.write(loginReques开发者_开发问答t);
    writeFuture.awaitUninterruptibly();

    if (writeFuture.getException() != null) {
        session.getConfig().setUseReadOperation(false);
        return false;
    }

    // retrieve the login response
    final ReadFuture readFuture = session.read();
    readFuture.awaitUninterruptibly();

    if (readFuture.getException() != null) {
        session.getConfig().setUseReadOperation(false);
        return false;
    }

    // stop blocking inbound messages
    session.getConfig().setUseReadOperation(false);

    // determine if the login info provided was valid
    final LoginResponse loginResponse = (LoginResponse)readFuture.getMessage();
    return loginResponse.getSuccess();
}

I can see on the server side that the LoginRequest object is retrieved, and a LoginResponse message is sent. On the client side, the DemuxingProtocolCodecFactory receives the response, but after throwing in some logging, I can see that the client gets stuck on the call to readFuture.awaitUninterruptibly().

I can't for the life of me figure out why it is stuck here based upon my own code. I properly set the read operation to true on the session config, meaning that messages should be blocked. However, it seems as if the message no longer exists by time I try to read response messages synchronously.

Any clues as to why this won't work for me?

The reason this wasn't working for me was because of an issue elsewhere in my code where I stupidly neglected to implement the message response encoder/decoder. Ugh. Anyway, the code in my question worked as soon as I fixed that.

I prefer this one (Christian Mueller : http://apache-mina.10907.n7.nabble.com/Mina-Client-which-sends-receives-messages-synchronous-td35672.html)

public class UCPClient { 

private Map<Integer, BlockingQueue<UCPMessageResponse>> concurrentMap = new ConcurrentHashMap<Integer, BlockingQueue<UCPMessageResponse>>(); 

// some other code 

public UCPMessageResponse send(UCPMessageRequest request) throws Throwable { 
    BlockingQueue<UCPMessageResponse> queue = new LinkedBlockingQueue<UCPMessageResponse>(1); 
    UCPMessageResponse res = null; 

    try { 
        if (sendSync) { 
            concurrentMap.put(Integer.valueOf(request.getTransactionReference()), queue); 
        } 

        WriteFuture writeFuture = session.write(request); 

        if (sendSync) { 
            boolean isSent = writeFuture.await(transactionTimeout, TimeUnit.MILLISECONDS); 

            if (!isSent) { 
                throw new TimeoutException("Could not sent the request in " + transactionTimeout + " milliseconds."); 

            } 

            if (writeFuture.getException() != null) { 
                throw writeFuture.getException(); 
            } 

            res = queue.poll(transactionTimeout, TimeUnit.MILLISECONDS); 

            if (res == null) { 
                throw new TimeoutException("Could not receive the response in " + transactionTimeout + " milliseconds."); 
            } 
        } 
    } finally { 
        if (sendSync) { 
            concurrentMap.remove(Integer.valueOf(request.getTransactionReference())); 
        } 
    } 

    return res; 
} 

}

and the IoHandler:

public class InnerHandler implements IoHandler { 

// some other code 

public void messageReceived(IoSession session, Object message) throws Exception { 
    if (sendSync) { 
        UCPMessageResponse res = (UCPMessageResponse) message; 
        BlockingQueue<UCPMessageResponse> queue = concurrentMap.get(res.getTransactionReference()); 
        queue.offer(res); 
    } 
} 

}

I had this exact problem. It turns out that it's because I was doing reads/writes in my IoHandler.sessionCreated() implementation. I moved the processing onto the thread that established the connection, instead of just waiting for the close future.

You must not use your login() function in IoHandler Thread :

If you call IoFuture.awaitUninterruptibly() in the override event function of IoHandler,

IoHandler don't work and get stuck.

You can call login() in other Thread and it will be work properly.