Echo example explaination

[이희승 (Trustin Lee)]

I've just split the EchoHandler into EchoClientHandler and
EchoServerHandler.  It should be easier to understand now. :)

  EchoClientHandler - http://tinyurl.com/kr5l8a
  EchoServerHandler - http://tinyurl.com/mxh2d5

What do you think?

Trustin

On Tue, 1 Sep 2009 14:05:05 +0900 (KST)
이희승 (Trustin Lee) <trustin at gmail.com> wrote:
> Indeed, this example is too tricky for a beginner to understand.  I
> need to separate server-side handler and client-side handler.
> 
> Trustin
> 
> On Tue, 1 Sep 2009 13:26:57 +0900 (KST)
> "J. Mi" <jmi258 at gmail.com> wrote:
> > Hi Christian,
> > 
> > Thanks! I got it. They echo each other just like "wild ping-pong". I
> > like that.
> > 
> > Cheers,
> > Jason
> > 
> > On Mon, Aug 31, 2009 at 8:24 AM, Christian Migowski
> > <chrismfwrd at gmail.com>wrote:
> > 
> > > Hi Jason,
> > >
> > > i'll try to comment the example, hope it helps:
> > >
> > > 1. in EchoClient.java line 63 an instance of EchoHandler.java
> > > firstMessage is initialized with numbers because the 2nd
> > > constructor is used
> > > 2. in EchoServer.java an instance of EchoHandler.java firstMessage
> > > is initialized as empty (i.e. no data) because the 1st constructor
> > > is used
> > > 3. in EchoClient.java line 67 the client connects to the server,
> > > when this is done, channelConnected() method of EchoHandler is
> > > invoked in both the client and the server, but with different
> > > processing: 3a) EchoHandler.channelConnected of EchoClient will
> > > send firstMessage that is initialized with numbers
> > > 3b)  EchoHandler.channelConnected of EchoServer will not send
> > > anything because firstMessage is empty (there is nothing to send,
> > > even IF write is called)
> > > 4. Echohandler.messageReceived of EchoServer is invoked because it
> > > received the message from the client, in this method the data
> > > received is echoed back to the client
> > > 5. now Echohandler.messageReceived of EchoClient is doing the same
> > > as the one of EchoServer in 4.) and the wild ping-pong begins
> > > until you terminate the program
> > >
> > > hope this helps,
> > > greetings,
> > > christian!
> > >
> > >
> > > On Sat, Aug 29, 2009 at 12:54 AM, J. Mi<jmi258 at gmail.com> wrote:
> > > > Hi Trustin or any other experienced Netty user,
> > > >
> > > > I've downloaded Netty 3.1.2. GA and am currently trying to learn
> > > > it via
> > > your
> > > > example of Echo. But I'm having a hard time understanding the
> > > > example. I started the server first and seeing a bunch of "0.000
> > > > MiB/s" output to
> > > the
> > > > console.
> > > >
> > > > I then started the client with the same port (as hard-coded in
> > > > the
> > > server)
> > > > of 8080. I then see the output to the console as a bunch "0.0nn
> > > > MiB/s"
> > > where
> > > > nn can be any number.
> > > >
> > > > I understand that the outout is from the thread
> > > > ThroughputMonitor.
> > > >
> > > > I'm not sure if I understand the scenario how things work
> > > > between the
> > > client
> > > > and the server.
> > > > The brief description from EchoClient.java is "Sends one message
> > > > when a connection is open and echoes back any received data to
> > > > the server." The brief description from EchoServer.java is
> > > > "Echoes back any received
> > > data
> > > > from a client."
> > > > The EchoHandler.java has the method below:
> > > >
> > > > public void channelConnected (ChannelHandlerContext ctx,
> > > ChannelStateEvent
> > > > e) {
> > > >
> > > > // Send the first message. Server will not send anything here
> > > >
> > > > // because the firstMessage's capacity is 0.
> > > >
> > > > e.getChannel().write(
> > > >
> > > > firstMessage);
> > > >
> > > > }
> > > >
> > > > So between the client and the server, who sends a message and
> > > > who echoes
> > > the
> > > > message?
> > > > When I added System.out
> > > > .println("Message from channelConnected: " +
> > > > firstMessage.toString()); in the method, I can see
> > > >
> > > > Message from channelConnected:
> > > > BigEndianHeapChannelBuffer(ridx=0, widx=0, cap=0)
> > > >
> > > > once when starting EchoClient.
> > > >
> > > > Could you please explain it to me? This example is a fundamental
> > > > one. It should be good starting point for me to understand
> > > > Netty's NIO framework.
> > > >
> > > > If there is a forum some where about this topic and where I
> > > > should post
> > > any
> > > > question like this, please advice as well.
> > > >
> > > > Thanks in advance
> > > > Jason
> > > > _______________________________________________
> > > > netty-dev mailing list
> > > > netty-dev at lists.jboss.org
> > > > https://lists.jboss.org/mailman/listinfo/netty-dev
> > > >
> > > >
> > >
> > > _______________________________________________
> > > netty-dev mailing list
> > > netty-dev at lists.jboss.org
> > > https://lists.jboss.org/mailman/listinfo/netty-dev
> > >
> 
> 
> 



-- 
Trustin Lee, http://gleamynode.net/