Thank you, Trustin. There actually is a contract between my server and their
remote peers that they shoud shut up while the server switches codecs (they can
start talking again after they receive a specific message giving notice of the
switch), so I wasn't even considering other circumstances. Lack of vision. :P
I will be waiting for a thread-safe "replace" method, to come with MINA 2.0.
Meanwhile, I changed my codec a bit to deal with both types of messages. You
suggested a codec that delegates to two child codecs appropriately. How exactly
could I implement that?
Thanks.
Fernando
Sat, 27 Jan 2007 23:56:05 +0900, "Trustin Lee" <[EMAIL PROTECTED]> escreveu:
>
> Hi Fernando,
>
> On 1/25/07, Fernando C. de Castro <[EMAIL PROTECTED]> wrote:
> >
> >
> > Hello,
> >
> > I am trying to do something that I don't even know is possible. Can I
> > change the codec "on the fly"?
> >
> >
> > Let me try and explain what I'm doing so you guys can follow my thoughts.
> >
> > On my SessionHandler (extends IoHandlerAdapter) I add a Codec to the
> > session as it's created:
> >
> > public void sessionCreated( IoSession session )
> > {
> >
> >
> > session.getFilterChain().clear();
> >
> >
> > session.getFilterChain().addFirst (
> > "idcodec",
> > new ProtocolCodecFilter(new
> > IDprotocolCodecFactory()));
> >
> > }
> >
> >
> > OK, so it loads my IDprotocolCodecFactory which has one messageEncoder and
> > one messageDecoder:
> >
> > public class IDprotocolCodecFactory extends DemuxingProtocolCodecFactory
> > {
> > public IDprotocolCodecFactory () {
> > super.register(IDmessageDecoder.class);
> > super.register(IDmessageEncoder.class);
> > }
> > }
> >
> >
> > This messageDecoder waits for 2 bytes, analyses them then returns
> > MessageDecoderResult.OK , and that fires the messageReceived() on my
> > SessionHanlder. So far, working as expected.
> >
> > Then, I would like to change the Codec (e.g. the "identification stage" is
> > over, now the server expects another kind of messages). So, on the
> > messageReceived(), I try to change the codec:
> >
> >
> > public void messageReceived( IoSession session, Object message )
> > {
> >
> > if (session.getFilterChain().contains("idcodec")){
> >
> > session.getFilterChain().remove("idcodec");
> > session.getFilterChain().addFirst (
> > "messagecodec",
> > new ProtocolCodecFilter(new
> > MyMessageCodecFactory()));
> >
> > }
> >
> > else {
> >
> > // after the "idcodec" was removed from the chain and
> > "messagecodec" was placed instead,
> > // messageReceived() will be triggered by "messagecodec" and will
> > always get to this 'else'.
> >
> > // (or so I expect...)
> > }
> >
> > }
> >
> > The MyMessageCodecFactory class is similar the presented
> > IDprotocolCodecFactory (extends DemuxingProtocolCodecFactory )
> >
> > Is it possible to change the codec like this? Because it's not
> > working. It's like I'm stuck with "idcodec" forever, it never changes to
> > "messagecodec".
>
>
> You can if there's a contract between you and your remote peer that the
> remote peer doesn't send any message while you switch your codec. If not,
> the idcodec can receive unwanted data, or data will be received when no
> codec is in action.
>
> You can work around this problem by creating a codec that delegates to the
> two child codecs appropriately. Of course, we will introduce an easier way
> to replace the codec on the fly like this in 2.0:
>
> session.getFilterChain().replace("codec", newCodec);
>
> HTH,
> Trustin
> --
> what we call human nature is actually human habit
> --
> http://gleamynode.net/
> --
> PGP key fingerprints:
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>
>
