There's quite a few different ways to tackle the mapping of XML to
databases. Certainly the XML-DBMS work looks interesting. (Shame they don't
offer a SAX interface ;-)
I saw this article lately that shows how to do XML-database mapping with the
common databases
http://www.xml.com/pub/a/2001/06/20/databases.html
There's a good article by Ronald Bourret that describes all of the various
strategies to maping XML to databases.
http://www.rpbourret.com/xml/XMLAndDatabases.htm
I guess it all depends on what you want to do with the XML. e.g. do you want
to support custom queries to find documents. Or custom queries on only parts
of documents (e.g. find all foo elements with an attibute bar="123" in any
document). One day XMLQuery may become a standard way of accessing these
kinds of things, though for some time I think database XPath engines will be
fine. (e.g. I think Oracle is now offering XPath indexing of documents in
Oracle 9i).
>From a dom4j perspective I'd like to make it as easy as possible for people
to use a variety of techniques for persisting documents, whether as BLOBs
(or as text files like in Oracle iFS) or as a persistent XML object model of
some kind or a hybrid approach with an XML indexing engine (e.g. to do XPath
queries then return URLs to the matching documents). So doing lazy fetching
of the document (and elements) as a document is navigated would be great.
Some object databases such as Versant allow clever pre-fetching to be done
to improve navigation performance.
Certainly the castor / jdo approach is useful too. Have Castor got a way of
generating a database schema for an XML Schema document yet? If so maybe its
time to write an adapter for dom4j?
James
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, June 26, 2001 12:53 PM
Subject: [dom4j-dev] DOM Long Term Persitence
> Hi Folks,
>
> I currently have the problem to descide how a DOM can be mapped into a
> Database.
> If think XML-DBMS, Version 1.01 seems to be very interesting, but its
build
> completly on top of DOM. Its a good idea to store a Element as a Table,
but
> how are Attributes handeld?
> But wat I really need is some kind of backward vistor who starts with
> deepest element, but that isn't coverd by GOF Pattern and I think it would
be an
> nice application of XPath.
> :-(
>
> Any ideas, comments? Is such a persitence layer welcome in dom4j? I think
we
> can use jdo (castor), too.
>
> Regards
>
> Toby
>
>
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