[topicmapmail] Topic Maps in a DBMS

[Kal Ahmed]

I can try :)

TM4J uses the Hibernate O-R mapping for its RDBMS implementation. This 
has some nice features for a Java programmer (like me) such as 
transparent mapping to/from Java data structures, and a run-time engine 
that requires no pre-processing of your source files.

The merging in TM4J is currently handled rather dynamically. It is 
possible to create unique strings for each "merge point" in a topic map 
(by defining a canonicalisation for subject indicators, subject 
addresses and scoped name strings). By recording those merge points for 
each topic, it then becomes a rather trivial task to query for all 
topics which merge with a given merge point and so, by extension, all 
topics which merge with a given topic. Of course, this all imposes a 
degree of runtime overhead, and so future work on TM4J will make a 
static merging process (probably based on the same ideas) optional. BTW, 
if you do want to read through the code, then its worth knowing that 
SIDP is my acronym for Subject Identity Point (aka merge point, but 
thats just what the name is known as...oh no, thats a whole other 
thread...;-)

Cheers,

Kal

Murray Altheim wrote:

> Dan Corwin wrote:
>
>> Hi Murray-
>>
>> If I want to persist various topic maps in a data base,
>> what table structures would I declare?
>>
>> I can visualize topic maps concretely as XTM fragments,
>> or sometimes as networks of Java objects.
>>
>> But what does a topic map look like under (e.g) mySQL?
>>
>> And is this black art or a cookbook design pattern?
>>
>> Dan
>
>
> Well, there've been several suggestions since my first reply, but
> apart from those is perhaps another:  open source is definititely
> not "black box", and you can look under the hood of the open source
> topic map engine TM4J to see how it handles storage of topic map
> objects. I use the in-memory implementation so I'm not familiar with
> how the DB code works, but TM4J also includes a number of DB
> implementations as well, hibernate and ozone, plus I believe several
> DB APIs. Perhaps Kal can elucidate when he gets a change.
>
> Murray
>
> ........................................................................... 
>
> Murray Altheim                         
> http://kmi.open.ac.uk/people/murray/
> Knowledge Media Institute
> The Open University, Milton Keynes, Bucks, MK7 6AA, 
> UK                    .
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