Question

I have a question about ClientBootStrap.
Here is the scenario;

1. Client_X wants to join Server_A.
2. But the Server_A somehow wants the Client_x to join in Server_B.
3. So Server_A sends Server_B’s info to Client_X for RECONNECTION
4. As soon as the Client_X gets the RECONNECTION message, he tries disconnecting from Server_A and tries to connecting to Server_B.
   But it fails. Because as soon as Client disconnects from Server_A, he cannot use the disconnected channel anymore.

This looks simple. But here is my implementation

    @Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e)throws Exception  {
    if(e.getMessage() instanceof SomePacket){
    ....
    }else if(e.getMessage() instanceof Reconnect){ //Server_A has sent a RECONNECT Message.(Redirection)
        Reconnect theReconnectPacket = (Reconnect)e.getMessage();
        String hostname = theReconnectPacket.getHostname();
        int port = theReconnectPacket.getPort();

        this.reconnectHost  = hostname;
    this.reconnectPort  = port;
    this.currentState   = 1;

    ctx.getChannel().disconnect();    //DISCONNECT FROM SERVER_A

     }
}

@Override
public void channelDisconnected(ChannelHandlerContext ctx,ChannelStateEvent e) throws Exception {

     if(this.currentState == 1){

        Channel disconnectedChannel = ctx.getChannel();

    if (!disconnectedChannel.isConnected()){

    SocketAddress destinationAddress = new InetSocketAddress(this.reconnectHost, this.reconnectPort);
           //TRYING TO RECONNECT SERVER_B
    disconnectedChannel.connect(destinationAddress);    //**Error Line:java.nio.channels.ClosedChannelException**

    }

      }


    super.channelDisconnected(ctx, e);
}

As you can see in the Error Line, I got this exception:java.nio.channels.ClosedChannelException. Couldn’t we use the same channel after it is disconnected?. Once it is disconnected, is it done?. How could we recreate a connection in the SimpleChannelHandler ?

Thanks for further comments 🙂

<<<<< NEW APPROACH >>>>>>

Ok. So in the SimpleChannledHandler , I use ClientBootStrap to connect a differentPort.

 @Override
public void channelDisconnected(ChannelHandlerContext ctx,ChannelStateEvent e) throws Exception {

       Channel disconnectedChannel = ctx.getChannel();
    final ClientDataObject oldObject = ClientDataState.clientObject.get(disconnectedChannel);

    if(oldObject.getClientState() == 1){

        if (!disconnectedChannel.isConnected()){

SocketAddress destinationAddress = new InetSocketAddress(this.reconnectHost, this.reconnectPort);

ChannelFuture connectFuture = bootstrap.connect(destinationAddress);

connectFuture.addListener(new ChannelFutureListener() {
    @Override
    public void operationComplete(ChannelFuture channelFuture) throws Exception {

        Channel newChannel = channelFuture.getChannel();
    ClientDataObject newObject =  ClientDataState.clientObject.get(newChannel);
                      newObject.setClientID(oldObject.getClientID());


                     newObject.setClientState(oldObject.getClientState());
                    newObject.setRoomId(oldObject.getRoomId());
                    newObject.setClientState(1);

                    ClientDataState.clientObject.set(newChannel, newObject);

                    Channels.write(newChannel, new Login(newObject.getClientID()));
               }});             

        }else{
                     //Channled connected
            }

    }

    super.channelDisconnected(ctx, e);

}

But I need to know some information of Client_X. As soon as the Client_x is disconnected the pipeline create another SimpleChannelHandler. So all my information is gone. I try to use ChannelLocal to keep state of the client. But it is also useless since it is related with channel object. When I connect to newChannel I cannot use old SimpleChannelHandlers’s data again. (like clientID,roomID etc.)

My point is how to store information without being effected by channel(session), I want to access the data from any channel handler.

The way to handle this question should we implement ChannelPipelineFactory like this?

   public class GameClientPipelineFactory implements ChannelPipelineFactory{

      private static final ClientStaticHandler SHARED = new ClientStaticHandler();  

           private Someobject o;
public GameClientPipelineFactory(Someobject refTOSomeObject) {
    super();
    this.o = refToSomeObject;
}

@Override
public ChannelPipeline getPipeline() throws Exception {
    // TODO Auto-generated method stub
    ChannelPipeline pipeline = Channels.pipeline();

    //pipeline.addLast("delimiter", new DelimiterBasedFrameDecoder(256, Delimiters.lineDelimiter()));
    pipeline.addLast("decoder", new GameClientDecoder());
    pipeline.addLast("encoder", new GameClientEncoder());
    pipeline.addLast("shared", SHARED); //I added this line

    pipeline.addLast("logicHandler", new GameClientLogicHandler(this.o));

    return pipeline;

}

But then how am I gonna use this ‘shared’ handler? Each time when I need a global object, should I ask to pipeline to get this handler and get any object from ‘shared’ handler? Isn’t this a long way?

Answer 1

Instead of trying to reopen a closed channel, try creating a new channel.

You may want to implement a callback to initiate a the creation of a new channel.