Protocol implementation, Netty socket server, J2ME client

[Nicholas Clare]

Hi Trustin,

You can post my example on the wiki, with pleasure.

I'm not all that experienced with networking code or NIO, but I do
find it very interesting. The work you've done with Netty seems
excellent, and I'd love to get involved more.

Nick

On Sat, Apr 11, 2009 at 5:20 PM, Trustin Lee <tlee at redhat.com> wrote:
> Hi Nick,
>
> Thank you so much for your contribution to this community first of all, Nick. :)
>
> Would you mind if I ask you to post your example to the wiki?  There
> are already a couple interesting example, and I believe yours will
> also be a great addition to the list:
>
>  * http://www.jboss.org/community/docs/DOC-13205
>
> With appreciation,
>
> — Trustin Lee, http://gleamynode.net/
>
> On Fri, Apr 10, 2009 at 9:40 PM, Nicholas Clare <nickclare at gmail.com> wrote:
>> Hi,
>>
>>  It doesn't seem like there's a simple example, although it is
>> mentioned in the ProtobufDecoder javadocs. I've written a very simple
>> example, which I've attached, but I not all that knowledgable of Netty
>> (well, not yet). So I hope my example can help, but maybe some more
>> experienced readers will be able to give some more advice.
>>
>> >From what I can see, to use the LengthFieldBasedFrameDecoder, you have
>> to layer another decoder on top of it. The
>> LengthFieldBasedFrameDecoder just makes sure that the decoder you
>> write doesn't have to keep checking if enough data has arrived yet.
>> Also, because the LengthFieldBasedFrameDecoder ensures that you get
>> just enough data at once, your custom decoder can be based on
>> OneToOneDecoder.
>>
>> I've put all the classes in one file to make it easier to send.
>>
>> I hope this helps you along,
>> Nick
>>
>> On Fri, Apr 10, 2009 at 1:22 PM, Karasko <karas at uralweb.ru> wrote:
>>>
>>> Thanks , Nicholas. I'll consider your ideas.
>>> Is there some example of LengthFieldBasedFrameDecoder using ? Didn't find it in DOCs.
>>>
>>>
>>> Hi
>>>
>>> A while ago I wrote server-side code to communicate with a J2ME
>>> client. Looking back now, the way I did it was wrong, so here's what
>>> I'd recommend for you: I'd use a simple binary protocol, that has a
>>> message length field. So a frame could be something like this:
>>>
>>> len (4 bytes) | message type (1 byte, or more, depending on what you
>>> need) | your content
>>>
>>> You can then use the LengthFieldBasedFrameDecoder class in Netty to do
>>> your decoding on the server side. On the client side, it shouldn't be
>>> too difficult to read in the length, and then read the rest of the
>>> message. You can also make this extensible by having the server or
>>> client ignore messages with a type it doesn't understand. So, for
>>> example, text messages could be message type 1, pngs message type 2,
>>> and so on.
>>>
>>> As for security, I'm sorry, I'm not too knowledgeable about that, so
>>> hopefully someone else can help you. I don't know what J2ME supports
>>> in that area, but it might be possible to do some basic encryption.
>>>
>>> I'm not really an expert, but I hope what I've suggested can maybe help you,
>>> Nick
>>>
>>> On Wed, Apr 8, 2009 at 2:09 PM, Karasko <karas at uralweb.ru> wrote:
>>>>
>>>> Hi, everyone.
>>>> I am writing a sokcet server, using Netty, which would be serve a requests from
>>>> J2ME devices (MIDP 2.0, CLDC). I am new person for networking, and concurrent programming,
>>>> so any advice or critics is accepted.
>>>>
>>>> Typical request is to retrieve some data from SQL server, based on text query.
>>>>
>>>> Response could be a text of various lenght, or sometimes binary data (i.e. PNG image).
>>>>
>>>> Can you advise some prototype of simple protocol for this, which i can
>>>> easily implement on client side J2ME device with standart packages:
>>>>
>>>> java.io.*;
>>>> javax.microedition.io;
>>>>
>>>> I need protocol to be
>>>> 1) extensible (adding new functionality doesn't require to rewrite code everywhere)
>>>> 2) compact (less traffic is better)
>>>> 3) secure (i don't know how to implement it yet, some advices will be nice)
>>>>
>>>>
>>>> I also want to know how to send an PNG image (or whatever binary data) over socket connection from server..
>>>> I think "new line" frame delimiter should be changed for smth else ?
>>>>
>>>> --
>>>> View this message in context: http://n2.nabble.com/Protocol-implementation%2C-Netty-socket-server%2C-J2ME-client-tp2604867p2604867.html
>>>> Sent from the Netty User Group mailing list archive at Nabble.com.
>>>>
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>>> --
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