Re: [topicmaps-comment] mapping topic maps on a relation database

[Murray Altheim <m.altheim@open.ac.uk>]

Kal Ahmed wrote:

> At 16:35 17/04/2002 +0000, Murray Altheim wrote:
[...]
>> Kal used the Ozone XML database, so it's only a matter of work to
>> reengineer it to use Xindice.
>
> Sorry I've been away from this forum for a little while - so I'm in 
> catchup mode ;-)


Hey Kal. Long time no see. I'm in Milton Keynes now, of all places.
A pub crawl is in order perhaps. Oxford perhaps? (I can't remember
where you are...)

 
> TM4J has two fully-featured backends - one based on storing the 
> processed XTM file in memory and one which uses Ozone - however the 
> Ozone backend does not make use of the Ozone XML database, it simply 
> uses Ozone to persist Java objects (and that works quite nicely! :-). 
> There is an experimental backend which is not complete yet which uses 
> XPath expressions and a DOM storage model - if/when completed, it should 
> be possible to hook that up to an XML::DB-compliant storage system.


I'll be releasing a first ferstoozel of Ceryle sometime soon, which
has an implementation of Xindice built in, using an XNode API I
developed to allow for metadata storage along with the nodes. Since
Xindice is XML:DB compliant, perhaps you could use Ceryle as a basis.
It also has a TouchGraph implementation built in, so even if you
ignore my XTM-to-TouchGraph code, you'd still have a foundation.


> In practical terms[1], I think that I agree with Murray that if you 
> restrict yourself to management of "consistent" topic maps - ones with 
> all merging resolved, use of XPath/XQuery over the topic map should be 
> doable - perhaps not as efficient as if you also created other indexing 
> structures - but not impossible.


One needs some sort of query system, and if one's database is XML-
based, then XPath is pretty good.

I'm perhaps not the purist that Steve Newcomb is, though I agree
with that sentiment. Given less than resounding resources, I may
have to settle for a topic map engine that doesn't quite do
*everything* but does most everything necessary within my system.
And maybe I'll manage to work it up to snuff over the next year.
I'd love to see an open source topic map engine in Java that I
could use, and perhaps the biggest barriers are the desire to
develop my own (as a learning exercise and challenge, as much as
anything) and the availability of a good API. I think we're working
on that latter one. I'll have to look at the "API" that my set of
Java objects exposes and compare that with the existing proposals.

Murray

......................................................................
Murray Altheim                  <http://kmi.open.ac.uk/people/murray/>
Knowledge Media Institute
The Open University, Milton Keynes, Bucks, MK7 6AA, UK

      In the evening
      The rice leaves in the garden
      Rustle in the autumn wind
      That blows through my reed hut.  -- Minamoto no Tsunenobu