[cddlm] CDL specification

[Paul Anderson]

Hi ...

I've been interested in trying to see if (some subset of) CDL would be
appropriate for describing system configuration data. In fact, I'm
arranging a short workshop in Edinburgh (April 28/29) to look at
existing XML representations of system config data and compare their
features - anyone interested would be most welcome ..

I'm interested particularly in the data description properties (rather
than the lifecycle management), and I am sure this will raise some
more detailed questions later. However ...

I am looking for a very simple language with a solid specification than
could form the basis for more complex descriptions. A couple of things
bother me about CDL:

1) The semantic specification is given in a rather loose way. If it intended
   that other people create implementations, then it is very important to 
   have a clear semantics. I'd like to see a slightly more formal
   specification of this, preferably with the resolution semantics
   presented in some abstract way that was independent of XML-specifics
   like "attributes" (I can say more about the problem here if anyone 
   is interested).

2) I can't seem to determine if there is intended to be semantic
   equivalence with SmartFrog. If so, then I would like to see a formal
   statement of this in the spec, and I'd like to see the semantics
   presented in such a way that this can be verified (at least informally).
   It seems very dangerous to talk glibly about "converting between SF
   and CDL" if there are subtle semantic differences.

3) I still don't understand how CDL is intended to be used. I had assumed
   that it was a low-level inter-program communication and would not be
   written by hand - rather it would be generated from some higher-level
   description. Is this the case, or will people be expected to hand-write
   CDL?

   If it is not intended by creation by hand, then why are the templates
   necessary at this level - any templates could be expanded at CDL
   generation time. I would certainly be happier with this, because I
   think that the requirements of the template mechanism are not
   yet well understood, and there is a danger of fixing on something
   in the standard which is inadequate.

   If it is intended for hand-creation, then this will not be suitable
   for use in many applications because of the difficulty involved.

All comments welcome

Many thanks

	Paul