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From Alex Karasulu <akaras...@apache.org>
Subject Re: Do we need to keep the encoder/decoder Provider stuff ?
Date Wed, 11 Aug 2010 20:16:55 GMT
Hi Emmanuel, Kiran, guys n gals,

On Mon, Aug 9, 2010 at 9:19 PM, Kiran Ayyagari <kayyagari@apache.org> wrote:

> On Mon, Aug 9, 2010 at 10:56 PM, Emmanuel Lecharny <elecharny@gmail.com>
> wrote:
> >  Hi,
> >
> > once upon a time, ie, 8 years ago, Alex codec the network frontend by
> > assuming that there will be some other codec used later. It made perfect
> > sense back then, as he first used an ASN.1 based codec named Snacc, which
> > was not ASL.2 compatible. Then he had to change and define its own
> version
> > of an ASN.1 codec, but as he wanted to check that the new codec was
> valid,
> > he designed the system to be able to switch the codec just to know if the
> > new codec was responsible for the failures he met, or something else.
> >
> > The rational was :
> > - if the server behaves the same way whether Snacc or Snickers (the new
> > codec) is used, then if the server has an issue, it means the codec is
> not
> > responsible
> > - OTOH, if the server behaves differently, then it's likey the new codec
> the
> > cause of the problem.
> >
> > That was a smart move, and it was leveraged again when I wrote Twix, the
> > third codec. I was able to do the same thing : compare the results
> obtained
> > with twix with what was obtained with Snickers.
> >
> > Eventually, we decided to ditch Snickers and to keep Twix, which was
> > renamed.
> >
> > So as of today, we use the so-called twix internally.
> >
>

Real nice recap of our codec development history. I enjoyed reading it and
remembering the last 8 years.

> Now, we still have a lot of remaining plumbery in place : all the classes
> > needed to declare which codec to use. Mainly, we have :
> > - Provider, an abstract class in charge of class loading the LdapProvider
> > - LdapProvider, a class used to create the LdapEncoder and LdapDecoder
> >
> > Those two classes are created when we create the FilterChain as soon as a
> > new session is initialized. More specifically, the ProtocolCodecFilter is
> > added into the chain, and before we can process any incoming messages
> from
> > the client, we initialize the codec, using the LdapProtocolCodecFactory
> > class to create the encoder/decoder instances.
> >
> > What are the essential elements ?
> > - the factory
> > - the encoder
> > - the decoder
> >
> > We should be able to get rid of the provider, assuming we won't even
> switch
> > the codec in the near or distant future. That would simplify the code
> which
> > is, to say the least, cryptic...
>
>
Exactly how much code are we talking about getting rid of? If I remember
correctly there was not that much to this code. Hopefully as Kiran writes
below these details are not exposed to the end user of the API however they
do have the power to change the codec. It by default uses the TWIX codec.


> > so, wdyt ? Should we keep the machinery that allow us to change the codec
> by
> > using an environment variable ?
> IMHO let us keep it, AFAIU this is transparent to the end or API user
> right? if yes, then I think it is
> better to remove it in another release.
>
> P.S:- perhaps this will save us some debug headaches, if at all arise,
> as we are making great
>         level of refactoring for the upcoming 2.0
>
>
If Kiran is correct about the exposure to the API end user, then I agree
with Kiran here unless of course there's a lot of headache you're dealing
with because of this Emmanuel. If you feel it's too much of a problem just
nix it.

Thanks,
-- 
Alex Karasulu
My Blog :: http://www.jroller.com/akarasulu/
Apache Directory Server :: http://directory.apache.org
Apache MINA :: http://mina.apache.org
To set up a meeting with me: http://tungle.me/AlexKarasulu

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