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From Jan Bartel <j...@mortbay.com>
Subject Re: [XML Parsing]
Date Mon, 01 Sep 2003 22:39:35 GMT
Apropos of Aaron's plea (see blow), I know I voted +1 for POJOs, but 
considering it a little more and given the difficulties experienced, are 
we sure that this is a necessary approach?

That is, do we have a clear set of use-cases and requirements that are 
met by POJOs or in fact a non-DOM model? I'm not against some POJO etc 
representation of the deployment descriptors, I just think we need to 
clearly understand the reasons why we need them.

I haven't actually seen any compelling use-cases yet - the ones I can 
enumerate would be better served by dealing directly with a DOM :

   + JSR88 deployment:
     the purpose of JSR88 beans is to deal with xml deployment
     descriptors. They need to perform xpath matching.

   + Web deployment:
     the concrete web containers (eg Jetty, Tomcat) deal with xml
     descriptors anyway, so they already DOM-ify them. This in fact
     leads to double parsing of web.xml descriptors: once by geronimo
     and once by the container. This could be optimised by modifying
     Jetty and Tomcat to operate on a DOM version of web.xml instead.
     However, if geronimo moves to POJO representations of the
     descriptors, then such a modification wouldn't be possible (or
     we'd have to introduce a POJO->DOM conversion).


So can we enumerate the advantages of a non-DOM representation of the
deployment descriptors?

Other requirements for whatever representation of the deployment 
descriptors we choose should include:

    + must be fast translating object <-> xml
    + must require minimum supporting jars (we *must* avoid /lib bloat)
    + must support xpath
    + nice if object <-> DOM was easily available


regards
Jan

Aaron Mulder wrote:
<snip>
> 	Also, the profusion of commons libraries required to get this
> running is a little frustrating.
> 
> 	Can we just use DOM please?


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