This is actually my first post on here and I have been trying to figure this out for some time but I am finally calling in the flag and going to try to get some help on this topic.
So I have a Client and a Server that was modeled after the echo client/server and the secure chat client/server. I am not interested in the SSL part of the chat and using the echo just to ensure that I am getting responses to and from the client/server. I will add all the pertinent code at the bottom of this post. The problem I am getting at the moment is that I can send a message from the server to the client upon the client connecting but I am not able to send a message from the client to the Server upon the server sending the client the initial message. The message being sent from the server is:
Welcome to the server!
The message from the client is
test
I should know that I got the message from the client cause it should echo back
[You] test
I do know that the Server sees the Client and it gives me status updates but I cannot send a message to the server for some reason. Now for a question on top of this... By some chance I am currently using a StringDecoder and StringEncoder as the Decoder and Encoder... If you are making a game (which is what I am doing) and you will have things like logins, player movements, world updates, etc... is sending Strings the best way to do this? I know I see a lot with byte streams and in my programming class I went through we touched on manipulating byte streams but I am still not 100% comfortable with them yet. If byte streams are the better/best way to do this then can someone please explain in some detail how it works to manipulate a byte stream to be able to handle different items.
As stated before this is the start of everything in the client:
public class Client {
public Client() {
// Initialize the window
GameWindow.init();
// Initialize the server connection
ClientHandler.init();
}
public static void main(String[] args) throws Exception {
// Set a default server address if one isn't specified in the arguments
if (args.length < 2 || args.length > 3) {
System.err.println("Usage: " + Client.class.getSimpleName() + " <host> <port> [<first message size>]");
System.err.println("Using default values.");
} else {
// Parse arguments
Settings.host = args[0];
Settings.port = Integer.parseInt(args[1]);
}
// start client
new Client();
}
ClientHandler:
package simple.client.net;
import java.net.InetSocketAddress;
import java.util.concurrent.Executors;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.jboss.netty.bootstrap.ClientBootstrap;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;
import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
import org.jboss.netty.channel.WriteCompletionEvent;
import org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory;
import simple.client.Settings;
public class ClientHandler extends SimpleChannelUpstreamHandler {
private static final Logger logger = Logger.getLogger(ClientHandler.class.getName());
public static Channel channel;
public ClientHandler() {
}
public static void init() {
// Configure the client.
ClientBootstrap bootstrap = new ClientBootstrap(new NioClientSocketChannelFactory(Executors.newCachedThreadPool(), Executors.newCachedThreadPool()));
// Set up the pipeline factory.
bootstrap.setPipelineFactory(new ClientPipelineFactory());
// Start the connection attempt.
ChannelFuture future = bootstrap.connect(new InetSocketAddress(Settings.host, Settings.port));
// Wait until the connection is closed or the connection attempt fails.
channel = future.awaitUninterruptibly().getChannel();
// This is where the test write is <<------
ChannelFuture test = channel.write("test");
if (!future.isSuccess()) {
future.getCause().printStackTrace();
bootstrap.releaseExternalResources();
return;
}
}
@Override
public void channelBound(ChannelHandlerContext ctx, ChannelStateEvent e) {
System.out.println("Bound: " + e.getChannel().isBound());
}
@Override
public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) {
System.out.println("Connected: " + e.getChannel().isConnected());
System.out.println("Connected: " + e.getChannel().getRemoteAddress());
}
@Override
public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) {
System.out.println("Closed: " + e.getChannel());
}
@Override
public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) {
System.out.println("Disconnected: " + e.getChannel());
}
@Override
public void channelOpen(ChannelHandlerContext ctx, ChannelStateEvent e) {
System.out.println("Open: " + e.getChannel().isOpen());
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {
System.out.println("Error: " + e.getCause());
}
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
System.out.println("Message: " + e.getMessage());
}
}
And finally the ClientPipeline:
package simple.client.net;
import static org.jboss.netty.channel.Channels.*;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.handler.codec.frame.DelimiterBasedFrameDecoder;
import org.jboss.netty.handler.codec.frame.Delimiters;
import org.jboss.netty.handler.codec.string.StringDecoder;
import org.jboss.netty.handler.codec.string.StringEncoder;
public class ClientPipelineFactory implements ChannelPipelineFactory {
public ChannelPipeline getPipeline() throws Exception {
ChannelPipeline pipeline = pipeline();
pipeline.addLast("framer", new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
pipeline.addLast("decoder", new StringDecoder());
pipeline.addLast("encoder", new StringEncoder());
pipeline.addLast("handler", new ClientHandler());
return pipeline;
}
}
Server Side:
package simple.server;
public class Server {
public static void main(String[] args) throws Exception {
ServerChannelHandler.init();
}
}
ServerChannelHandler:
package simple.server;
import java.net.InetSocketAddress;
import java.util.concurrent.Executors;
import java.util.logging.Logger;
import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;
import org.jboss.netty.channel.group.ChannelGroup;
import org.jboss.netty.channel.group.DefaultChannelGroup;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
public class ServerChannelHandler extends SimpleChannelHandler {
private static final Logger logger = Logger.getLogger(ServerChannelHandler.class.getName());
private static ChannelGroup channels;
private static ServerBootstrap bootstrap;
public ServerChannelHandler() {
}
/**
* Initialize the Server Channel Handler
*/
public static void init() {
// create a channels group to add incoming channels to
channels = new DefaultChannelGroup();
// create the server bootstrap (fancy word for pre-made server setup)
bootstrap = new ServerBootstrap(new NioServerSocketChannelFactory(
Executors.newCachedThreadPool(), Executors.newCachedThreadPool()));
// set the server pipeline factory
bootstrap.setPipelineFactory(new ServerPipelineFactory());
// server settings
bootstrap.setOption("keepAlive", true);
// bind the server to the port
bootstrap.bind(new InetSocketAddress(Settings.PORT_ID));
}
@Override
public void channelBound(ChannelHandlerContext ctx, ChannelStateEvent e) {
System.out.println("Bound: " + e.getChannel());
}
@Override
public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) {
System.out.println("Connected: " + e.getChannel());
channels.add(e.getChannel());
e.getChannel().write("Welcome to the test server!\n\r");
}
@Override
public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) {
System.out.println("Closed: " + e.getChannel());
}
@Override
public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) {
System.out.println("Disconnected: " + e.getChannel());
}
@Override
public void channelOpen(ChannelHandlerContext ctx, ChannelStateEvent e) {
System.out.println("Open: " + e.getChannel());
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {
System.out.println("Error: " + e.getCause());
}
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
System.out.println("Message: " + e.getMessage());
for (Channel c : channels) {
if (e.getMessage().equals("shutdown")) {
shutdown();
}
if (c != e.getChannel()) {
c.write("[" + e.getChannel().getRemoteAddress() + "] " + e.getMessage() + "\n\r");
} else {
c.write("[You] " + e.getMessage() + "\n\r");
}
}
}
/**
* Shuts down the server safely
*/
public static final void shutdown() {
channels.close();
bootstrap.releaseExternalResources();
System.exit(0);
}
}
ServerPipelineFactory:
package simple.server;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.handler.codec.frame.DelimiterBasedFrameDecoder;
import org.jboss.netty.handler.codec.frame.Delimiters;
import org.jboss.netty.handler.codec.string.StringDecoder;
import org.jboss.netty.handler.codec.string.StringEncoder;
import simple.server.decoder.Decoder;
import simple.server.encoder.Encoder;
public class ServerPipelineFactory implements ChannelPipelineFactory {
@Override
public ChannelPipeline getPipeline() throws Exception {
ChannelPipeline pipeline = Channels.pipeline();
pipeline.addLast("framer", new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
pipeline.addLast("decoder", new StringDecoder());
pipeline.addLast("encoder", new StringEncoder());
pipeline.addLast("handler", new ServerChannelHandler());
return pipeline;
}
}
Once again everyone I appreciate any help you can give me on understanding this.
You forgot to append \r\n
to "test"
. It should be: channel.write("test\r\n")
.`
As you see from the pipeline, the decoding part is composed of two handlers. The first one splits and merges the received data into a single line of string and strips the line ending from it. The second one converts the single line of string into java.lang.String
.
On the encoding side, there's only one handler, which converts a java.lang.String
into ByteBuf
, and that's all it does. Perhaps it is better introduce a handler called LineEncoder
, LineDecoder
, and LineCodec
that does the usually expected job: https://github.com/netty/netty/issues/1811