[Demexp-dev] Re: Use of CDuce

[David MENTRE]

Hello Serge,

Serge Leblanc <address@hidden> writes:

> On Wed, 2004-10-13 at 22:00, David MENTRE wrote:
>
>> My main issue is to avoid converting the whole XML file into an OCaml
>> representation and then convert this representation into the demexp data
>> structures. Does CDuce help in this?
>> 
>
>
> Oui, c'est précisément ce que je souhaitais montrer dans l'exemple. 
> De plus CDuce permet d'avoir un meilleur contrôle sur les types avec des
> levés d'exception 'raise' si le document ne respecte pas le schema ou la
> dtd qui est vu par CDuce comme un type. 

[ Serge: yes. Moreover, CDuce has a fine control on types and raises
  exceptions if the document does not follow the DTD or schema. ]

Great. I love that! This is a very convincing argument for me. Anything
that can help the handling of error cases is Good Software
Engineering(tm).


[ about PXP ]
> La manipulation de l'arbre XML au niveau de PXP n'est pas trivial. C'est
> du même ordre que l'utilisation de DOM en XML et l'équipe CDuce a déjà
> fait ce travail pour toi.

[ Serge: using PXP is not so easy. CDuce has already done part of the
  work. ]

I had that feeling but thank you for confirming it.

[ about XML machinery (PXP, CDuce) complexity ]
> Aujourd'hui tu as ce jugement car la structure du document XML est
> simple. L'utilisation d'XML n'est pratiquement pas justifiée à part pour
> une question d'ouverture.
> Mais rapidement le schéma du document va se complexifier. Par exemple
> vous serez certainement amenés à ajouter dans les informations de login
> la date du dernier accès et peut-être une durée de validité du login
> (autorisation de votes ponctuels pour le personnel d'entreprise). 

[ Serge: todays, the XML structure is quite simple but it might be more
  complicated in the futures (e.g. new fields for last access time). ]

Well, I'm still convinced that currently and in the near future, our XML
needs will be pretty simple. However:

 - CDuce might help to write translation tool for the XML bases from one
   version of demexp to the next one (typically,
   demexp-without-delegation to demexp-with-delegation);

 - I like your points about error handling and easiness of XML
   manipulation descriptions.

So, considering latest move of the CDuce team and Alain Frish on the
licensing issue, I agree to give CDuce a try for XML handling.

So, if you are interested (and you seem to be interested ;), you can
start working on the demexp bases (please refer to my previous email for
details). As I said previously, I want to finish the graphical interface
first. So I won't integrate any of your patches in the follwing weeks or
even months. But XML is the second item on the to do list. ;) And any
help on designing DTD, Schema and literate version of demexp code would
be very appreciated.

> J'ai complété  le fichier d'exemple pour tu puisses mieux comprendre
> l'intérêt de CDuce.

[ Serge: I have completed the example file to understand details. ]

I've not tested them yet but will give them a try.

Yours,
david
-- 
pub  1024D/A3AD7A2A 2004-10-03 David MENTRE <address@hidden>
 5996 CC46 4612 9CA4 3562  D7AC 6C67 9E96 A3AD 7A2A