Since we're talking about databases...

W. Eliot Kimber eliot at
Tue Feb 2 04:30:55 GMT 1999

At 01:29 AM 2/2/99 +0000, Clark Evans wrote:
>I'm rather new to the list.  I was wondering if there is any
>current (open source?) work for storing XML in relational 
>databases.  I was thinking of using PostgreSQL.

>c) GROVES look pretty cool.  Is there anyone working
>on a xml property set? Would it be smart to implement
>an xml database upon the groves abstraction, or would
>a direct (DOM) based implemention be better? 

David Megginson's Work Group is charged with developing the official
abstract data model for XML--but I doubt it will be defined as a property
set using the PSDR approach.  Defining a grove plan over the SGML property
set that reflects what XML gives you is pretty trivial and adding some
properties for XML-specific stuff (dare I say it, namespaces?) wouldn't be
too hard. 

TechnoTeacher ( is pursing large-scale grove-based systems.
We've certainly talked about relational vs object approaches. They'll
probably have to do both eventually.

I'm in the process of rewriting my PHyLIS grove manager/HyTime engine in
Python. As there's an RDBMS package for Python, I'm thinking about trying
to put it under PHyLIS as a persistent grove store. Not sure how it will
work, but it will be easy to experiment with.

>d) How hard would it be to develop a transition/rewrite
>engine (say by modifying JADE) to work using a database 
>store instead of memory?  Thoughts?  Any work in 
>this area?

Shouldn't be too hard.  One way to do it is to simply put a grove API over
a database, so that the grove is really just a bunch of indirections to the
real data. This is the way I've designed my GroveNode class for PHyLIS, to
enable this sort of grove binding. There's probably a more efficient way to
do this from a CS standpoint, but it seemed pretty easy to implement.

I wouldn't be surprised if Alex Milowski, of Copernican Solutions and Veo
Systems, hasn't done some of this stuff-he put a lot of effort into
building a completely grove-based server system.


<Address HyTime=bibloc>
W. Eliot Kimber, Senior Consulting SGML Engineer
ISOGEN International Corp.
2200 N. Lamar St., Suite 230, Dallas, TX 75202.  214.953.0004

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