Structured message reading problem in Netty.

[Trustin Lee]

Hi Manish,

I hope you are not discouraged by previous comment.

I'd like to recommend you to use ReplayingDecoder in this case.

  public class MyDecoder extends ReplayingDecode<VoidEnum> {
    @Override
    protected Object decode(..., buf, ...) {
      int messageLength = buf.readInt();
      int headerLength = buf.readInt();
      return buf.readBytes(messageLength + headerLength);
    }
  }

Than the handler placed after 'MyDecoder' will get a ChannelBuffer
with expected length.  For example, if a message whose messageLength
is 10 and headerLength is 6, you will get a ChannelBuffer whose
readable bytes are 4 + 4 + 6 + 10.

Let me know if you have more questions. :)

HTH,

— Trustin Lee, http://gleamynode.net/

On Fri, Apr 24, 2009 at 2:16 PM, manishr22 <manishr22 at gmail.com> wrote:
>
> Hi Trustin,
>
> Sorry to bug you guys much.
>
> I did read the explanation about FrameDecoder and did the earlier
> implementation using the same. In my earlier post i gave those source code
> too. Since that was also having problem in buffer's capacity() and
> resetReaderIndex().
>
> I am sorry to give an impression like i wanted to get my code fixed by
> someone else, but i never had this intention, i only wanted to get the
> advice and opinion from Netty expert, since i was learning this.
>
> Regards
> Manish
>
> Trustin Lee-2 wrote:
>>
>> Hi Manish,
>>
>> Looking from your code, you don't have a FrameDecoder or
>> ReplayingDecoder in a pipeline, which means you have a good chance to
>> receive only partial data, which leads to IndexOutOfBoundsException.
>> Did you have a chance to read the first chapter of the user guide?
>> There's good amount of explanation about this issue there.
>>
>> You and other community members have exchanged quite a lot of
>> questions and answers so far.  My impression so far is that you just
>> want people to fix your code.  We could solve your problem just by
>> writing the fixed code for you, but it would be much better for you to
>> follow all the step demonstrated in the user guide.  Then you will
>> know what is wrong with your current code very easily.
>>
>> Also, you might find the factorial example more useful than the
>> discard example for your case.
>>
>> — Trustin Lee, http://gleamynode.net/
>>
>> On Thu, Apr 23, 2009 at 8:45 PM, manishr22 <manishr22 at gmail.com> wrote:
>>>
>>> Hi,
>>>
>>> I am new to netty and tried writing netty-server as per my requirement
>>> seeing various examples. But i am not getting the result correctly.
>>>
>>>
>>> I am trying to write a netty server that can read the that will read the
>>> message-structre from normal synchronous multi-threaded client ( say 10
>>> client is sending 1000 messages each ) to the server.
>>>
>>>
>>> By message structure i mean my client is sending the message in the
>>> format :
>>>
>>>
>>> [MESSAGE 1-CLIENT 1]    message-length(first 4 byte) header length(next 4
>>> byte) data (including
>>>
>>> header and body as specified bytes of message length and header length)
>>>
>>>
>>> [MESSAGE 2-CLIENT 1]    message-length(first 4 byte) header length(next 4
>>> byte) data (including
>>>
>>> header and body as specified bytes of message length and header length)
>>>
>>>
>>> ........
>>>
>>> ........
>>>
>>> [MESSAGE 1-CLIENT 2]    message-length(first 4 byte) header length(next 4
>>> byte) data (including
>>>
>>> header and body as specified bytes of message length and header length)
>>>
>>>
>>> [MESSAGE 2-CLIENT 2]    message-length(first 4 byte) header length(next 4
>>> byte) data (including
>>>
>>> header and body as specified bytes of message length and header length)
>>>
>>> ....
>>> .....
>>>
>>> [For N number of client and N
>>> http://n2.nabble.com/file/n2682454/netty.zip
>>> netty.zip  number of messages]
>>>
>>> and now my netty server should read all the different messages from
>>> client/s
>>> and do the proper message parsing and do some business operation.
>>>
>>>
>>> How i can implement the reading of message-structure using netty.
>>>
>>>
>>> I saw several example and implemented something in it. but its not giving
>>> the appropriate result rather i am getting exception all the time.
>>>
>>> The basic source code which i tried for this is also attached for
>>> reference.
>>>
>>> Any suggestion and help with some sample code will be really appreciated.
>>>
>>>
>>> Regards
>>>
>>> Manish
>>>
>>>
>>>
>>> --
>>> View this message in context:
>>> http://n2.nabble.com/Structured-message-reading-problem-in-Netty.-tp2682454p2682454.html
>>> Sent from the Netty User Group mailing list archive at Nabble.com.
>>>
>>> _______________________________________________
>>> netty-users mailing list
>>> netty-users at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/netty-users
>>>
>>
>> _______________________________________________
>> netty-users mailing list
>> netty-users at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/netty-users
>>
>>
>
> --
> View this message in context: http://n2.nabble.com/Structured-message-reading-problem-in-Netty.-tp2682454p2689756.html
> Sent from the Netty User Group mailing list archive at Nabble.com.
>
>
> _______________________________________________
> netty-users mailing list
> netty-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/netty-users
>