Re: Create a web interface to query a XML database

I forgot to mention something which is important in taking a decision
as for what technology to use. With PHP-MySQL the user can send
queries to the database from a web form and get the results -- I
understood this can be done with XRX/XSLT/etc. However, with PHP-MySQL
I can also input data to the database and add new registers or
maintain the database updating the content of certain existing
registers, with phpmyadmin or with ad-hoc web forms. Can this be done
with the XML-based technologies?

We've been using variuos XML (Tamino, eXist, Sedna) and relational db systems
(MySQL, Oracle) as a backend for a web app that receives and sends XML files.
All of the mentioned XML db systems support XQuery, but implement it
differently, since updates are not standardised in XQuery. There is a fair
amount of similarity, but if you don't want to rely on a specific product
it will probably cost you a lot of work to abstract away from the database.

Our general experience is that queries can be very fast in all mentionend
XML db systems. However, updates and large data volumes separate the wheat from
the chaff. eXist's performance (last version we used was 1.2.1) degraded fast
when the number of docs exceeded several thousands, so it seems it cannot handle
large data volumes. On the other hand, eXist has very good standards support.
Sedna was very fast with queries, even when we had over one million docs in the
database, but updates to a single doc could take up to ten minutes then. Adding
docs was still very fast. Only Tamino showed good performance with both queries
and updates, regardless of the data volume.

However, both MySQL and Oracle outperformed the XML db systems in every aspect
and required far less disk space. And there are ORM frameworks like Hibernate
that make it easy to switch between relational db sytems.

BTW, clients interface withe the web app through web services, so no
XSLT involved here.

If you have further questions around our experience with XML db systems, I
suggest you email directly to me, since this is certainly off-topic.

*  michael.schaefer@xxxxxxxxxxx    http://www.destatis.de
*                                  http://www.statspez.de
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