I am new to Netty and trying to writing a server client project using it. I am able to send the request from client to the server successfully and am able to process it too using my listeners. But the issue am having is when I try to write the response back to the channel for the client processing on the server side using channel.write(), I am unable to get it back at client.
This is my first time on stackoverflow, please forgive if I make some mistake while asking the question or for indentation issues while posting the code.
This is my server :
public class SocketIOServer {
private Logger log = Logger.getLogger(getClass());
private ServerBootstrap bootstrap;
private Channel serverChannel;
private int port;
private boolean running;
public SocketIOServer(int port) {
this.port = port;
this.running = false;
}
public boolean isRunning() {
return this.running;
}
public void start() {
bootstrap = new ServerBootstrap(new NioServerSocketChannelFactory(
Executors.newCachedThreadPool(),
Executors.newCachedThreadPool()));
try {
EncryptionManager encryptionManager = EncryptionManager.getInstance();
} catch (Exception ex) {
java.util.logging.Logger.getLogger(SocketIOServer.class.getName()).log(Level.SEVERE, null, ex);
}
// Set up the event pipeline factory.
bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
@Override
public ChannelPipeline getPipeline() throws Exception {
ChannelPipeline pipeline = pipeline();
pipeline.addLast("decode", new FrameDecoder(){
@Override
protected Object decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buf) throws Exception {
// Make sure if the length field was received.
if (buf.readableBytes() < 4) {
// The length field was not received yet - return null.
// This method will be invoked again when more packets are
// received and appended to the buffer.
return null;
}
// The length field is in the buffer.
// Mark the current buffer position before reading the length field
// because the whole frame might not be in the buffer yet.
// We will reset the buffer position to the marked position if
// there's not enough bytes in the buffer.
buf.markReaderIndex();
// Read the length field.
int length = buf.readInt();
// Make sure if there's enough bytes in the buffer.
if (buf.readableBytes() < length) {
// The whole bytes were not received yet - return null.
// This method will be invoked again when more packets are
// received and appended to the buffer.
// Reset to the marked position to read the length field again
// next time.
buf.resetReaderIndex();
return null;
}
// There's enough bytes in the buffer. Read it.
ChannelBuffer frame = buf.readBytes(length);
// Successfully decoded a frame. Return the decoded frame.
return frame;
}
});
pipeline.addLast("handler", new GameServerHandler());
return pipeline;
}
});
bootstrap.setOption("backlog", 1024);
// Bind and start to accept incoming connections.
this.serverChannel = bootstrap.bind(new InetSocketAddress(port));
this.running = true;
log.info("Server Started at port [" + port + "]");
System.out.println("Server Started at port [" + port + "]");
}
public static void main(String[] args) {
SocketIOServer server = new SocketIOServer(8888);
server.start();
}
Server Handler class :
public class GameServerHandler extends SimpleChannelUpstreamHandler {
@Override
public void handleUpstream(
ChannelHandlerContext ctx, ChannelEvent e) throws Exception {
if (e instanceof ChannelStateEvent) {
logger.info(e.toString());
}
super.handleUpstream(ctx, e);
}
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception{
System.out.println("Following data recieved at the server");
ConnectionManager connectionManager = ConnectionManager.getInstance();
List<Object> paramsList = new ArrayList<Object>();
NetworkClient client = connectionManager.getNetworkClient(e.getChannel().getId());
ChannelBuffer ebuf = (ChannelBuffer)e.getMessage();
if( client == null ) {
client = new NetworkClient(e.getChannel());
connectionManager.addNetworkClient(e.getChannel().getId(), client);
}
byte [] encryptedData = ebuf.array();
System.out.println("encrypted data size : "+ encryptedData.length);
System.out.println("encrypted data : "+ encryptedData);
byte [] decrpytedData = null;
try {
decrpytedData = EncryptionManager.getInstance().decrypt(encryptedData, EncryptionManager.getInstance().getPrivateKey());
}catch (Throwable ee){
ee.printStackTrace();
}
ChannelBuffer buf = ChannelBuffers.buffer(decrpytedData.length);
buf.writeBytes(decrpytedData);
while(buf.readable()) {
long gameTableId = buf.readLong();
GameTable gameTable = gameTableController.getTablePeer(gameTableId);
if(gameTable == null) {
GameTable newGameTable = new GameTable();
newGameTable.setTableId(gameTableId);
newGameTable.registerListeners();
gameTableController.storeTablePeer(gameTableId, newGameTable);
}
int eventHash = buf.readInt();
String eventName = getEventNameFromEventHash(eventHash);
int paramCount = buf.readInt();
if(paramCount > 0) {
for(int count=0;count<paramCount;count++) {
populateParamList(buf, paramsList);
}
if(!NetworkMessenger.broadcastToAllFromNetwork(eventName, client, paramsList.toArray(new Object[paramsList.size()]))) {
logger.debug( "Unhandled Data:" + eventName);
System.out.println("Unhandled Data:" + eventName);
}
logger.debug( "Data processed successfully for " + eventName + " game table id : " + gameTableId);
System.out.println("Data processed successfully for " + eventName + " game table id : " + gameTableId);
}
break;
}
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {
e.getCause().printStackTrace();
logger.log(
Level.WARN,
"Unexpected exception from downstream.",
e.getCause());
Channel ch = e.getChannel();
ch.close();
}
@Override
public void channelConnected(
ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
ChannelFuture cf = e.getFuture();
cf.addListener(new Greeter());
}
@Override
public void channelDisconnected(
ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
// Unregister the channel from the global channel list
// so the channel does not receive messages anymore.
channels.remove(e.getChannel());
}
private static final class Greeter implements ChannelFutureListener {
public void operationComplete(ChannelFuture future) throws Exception {
if (future.isSuccess()) {
// Once session is secured, send a greeting.
String welcomeMsg = "Welcome";
ChannelBuffer cb = ChannelBuffers.dynamicBuffer();
cb.writeBytes(welcomeMsg.getBytes());
future.getChannel().write(cb);
// Register the channel to the global channel list
// so the channel received the messages from others.
channels.add(future.getChannel());
} else {
future.getChannel().close();
}
}
}
}
This is my client class :
public class Clientbot {
public static void main(String[] args) throws IOException {
String host = "localhost";
int port = 8888;
final ChannelBuffer buf = ChannelBuffers.dynamicBuffer();
// Configure the client.
ChannelFactory factory =
new NioClientSocketChannelFactory(
Executors.newCachedThreadPool(),
Executors.newCachedThreadPool());
ClientBootstrap bootstrap = new ClientBootstrap(factory);
bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
public ChannelPipeline getPipeline() {
ChannelPipeline pipeline = Channels.pipeline();
pipeline.addLast("decode", new FrameDecoder(){
@Override
protected Object decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buf) throws Exception {
// Make sure if the length field was received.
if (buf.readableBytes() < 4) {
return null;
}
buf.markReaderIndex();
// Read the length field.
int length = buf.readInt();
// Make sure if there's enough bytes in the buffer.
if (buf.readableBytes() < length) {
buf.resetReaderIndex();
return null;
}
// There's enough bytes in the buffer. Read it.
ChannelBuffer frame = buf.readBytes(length);
// Successfully decoded a frame. Return the decoded frame.
return frame;
}
});
pipeline.addLast("handler", new ClientHandler());
return pipeline;
}
});
bootstrap.setOption("tcpNoDelay", true);
bootstrap.setOption("keepAlive", true);
ChannelFuture future = bootstrap.connect(new InetSocketAddress(host, port));
// Wait until the connection attempt succeeds or fails.
Channel channel = future.awaitUninterruptibly().getChannel();
if (!future.isSuccess()) {
future.getCause().printStackTrace();
bootstrap.releaseExternalResources();
return;
}
ChannelFuture lastWriteFuture = null;
try {
lastWriteFuture = writeSecureSampleData(channel, buf);
} catch (Exception ex) {
ex.printStackTrace();
}
// Wait until all messages are flushed before closing the channel.
if (lastWriteFuture != null) {
lastWriteFuture.awaitUninterruptibly();
}
// Close the connection. Make sure the close operation ends because
// all I/O operations are asynchronous in Netty.
channel.close().awaitUninterruptibly();
// Shut down all thread pools to exit.
bootstrap.releaseExternalResources();
}
private static ChannelFuture writeSecureSampleData(Channel channel, ChannelBuffer buffer) throws Exception {
long gameId = 1234;
ChannelBuffer buf = ChannelBuffers.buffer(256);
buf.writeLong(gameId);
writeParamsForLogin(buf);
byte [] data = buf.array();
byte [] encryptedData = EncryptionManager.getInstance().encrypt(data, EncryptionManager.getInstance().getPublicKey());
int size = encryptedData.length;
buffer.writeInt(size);
buffer.writeBytes(encryptedData);
ChannelFuture writeFuture = channel.write(buffer);
return writeFuture;
}
private static void writeParamsForLogin(ChannelBuffer buf) {
int eventHash = getEventHash("Login");
buf.writeInt(eventHash);
int paramCount = 3 ; // in case of PlayerToken 2 parameters to be send : player id + player token
buf.writeInt(paramCount);
// version , E , N
String version = "1.0";
buf.writeInt(dataType_String);
buf.writeInt(version.length());
buf.writeBytes(version.getBytes());
String E = "61";
buf.writeInt(dataType_ByteArray);
buf.writeInt(E.length());
buf.writeBytes(E.getBytes());
String N = "53";
buf.writeInt(dataType_ByteArray);
buf.writeInt(N.length());
buf.writeBytes(N.getBytes());
}
}
and the client handler class :
public class ClientHandler extends SimpleChannelUpstreamHandler {
@Override
public void messageReceived(
ChannelHandlerContext ctx, MessageEvent e) {
System.err.println(e.getMessage());
System.out.println("Message Recieved");
ChannelBuffer buf = (ChannelBuffer)e.getMessage();
while (buf.readable()) {
System.out.println((char) buf.readByte());
System.out.flush();
}
}
@Override
public void exceptionCaught(
ChannelHandlerContext ctx, ExceptionEvent e) {
logger.log(
Level.WARNING,
"Unexpected exception from downstream.",
e.getCause());
e.getCause().printStackTrace();
e.getChannel().close();
}
}
On receiving the request data on the server, I am processing it and writing back the response using the following method :
private static boolean sendMessage(NetworkClient targetObject, String eventName, Object[] params) {
logger.debug("Sending message for the event : " + eventName);
if(targetObject == null) {
sendMessageToAll(eventName, params);
} else {
if (targetObject.getClientChannel() == null) {
logger.error("Target not defined.");
return false;
}
Channel clientChannel = targetObject.getClientChannel();
ChannelBuffer buf = ChannelBuffers.dynamicBuffer();
long hash = getHashString(eventName);
buf.writeInt(512);
buf.writeLong(hash);
if(params != null) {
buf.writeInt(params.length);
for(Object param : params) {
int type = getTypeOfObject(param);
buf.writeInt(type);
writeParamToBuffer(buf, type, param);
}
}
ChannelFuture cf = null;
try {
cf = clientChannel.write(buf);
if(cf.isSuccess()){
System.out.println("Written to client successfully");
}
} catch (Exception e) {
logger.error("Error in broadcasting for event : " + eventName, e);
} finally {
}
}
return false;
}
This code is still a work in progress, so you might find lot of "not required" stuff in there. I just wanted to show the logic that I am trying to use and want to know why it is not working.
I have taken help from examples at http://docs.jboss.org/netty/3.2/xref/org/jboss/netty/example/ for writing this.
Thanks in advance for any help.
