Xml Mailing List: Re: comments on draft-frascone-aaa-xml-dictionary-00.txt

[Yoshihiro Ohba (yohba]

On Wed, May 01, 2002 at 04:34:06PM -0500, David Frascone wrote:
> I'm glad someone else is using the dictionary!  I agree completely with
> your addition of the proxyable and error bit.  They were introduced after
> this document was created.  I'll implement those changes right away.
> 
> I'm copying the other authors on this response.

Thanks for the cc'ing.  After having implemented both ABNF- and
XML-based dictionaris, I thought it is much easier to implement than
ABNF-based dictionary.  I really appreciate the authors' work.

I try to reply to the most essential comment from you.

> Ok, I see where you were going, but this is very confusing to me.  And, more
> importantly, I think it is going to be useless information to a parser. 
> (Well, to be honest, not useless, but VERY difficult to have a parser 
> implement all these rules to do runtime symantic checking of Diameter
> messages)

Hmm, I have implemented runtime symantic checking of Diameter
messages, and it was NOT difficult.  It makes application (NASREQ,
MobileIP, etc) programs simpler since they do not have to take care of
the order and the number of repetition, of the AVPs in a command.
I have to say it is useful.

Relating to this, the most important issue seems to be whether the
XML-based dictionary should be equivalent with ABNF-based dictionary,
specifically whether the XML dictionary should make distinction on
fixed, required and optional AVPs in command definition as the ABNF
does.  I suggest the XML-based dictionary being equivalent to the
ABNF-based one.  Otherwise, runtime symantic checking is not possible.

Even if a dictionary parser implementation does not support runtime
symantic checking, the suggested schema modification to make
distinction on fixed, required and optional AVPs should not affect
such an implementation since the dictionary parser program can simply
ignore fixed, required and optional tags just as if it were not there.

I can send you a documentation on our message parser implementation
(that supports both ABNF- and XML-based dictionaries as well as
runtime symantic checking of Diameter messages), since we would like
to contribute to open source Diameter project as much as possible.

Yoshihiro Ohba