Hi all,
I am currently thinking about ways to support complete conformance with
Annex F of XTM 1.0. Briefly, XTM defines the concept of a "consistent"
topic map in which all topics are merged and all duplicates are suppressed
in conformance with XTM 1.0 Annex F.
In my mind there are three possible approaches to supporting this:
1) A "static translation" approach - you can construct any topic map you
like which may or may not be a "consistent" topic map. You then use a
utility to process the topic map into a consistent topic map - this would
remove the dynamic merges from the topic map and would eliminate all
duplicates. This is currently implemented as org.tm4j.topicmap.Compressor
(needs a better name!)
2) A "dynamic" layer over the basic TM4J implementation - This approach is
a shim layer which wraps any TopicMapProvider and creates a layer of
consistency validation around all methods which can update the topic - the
shim makes sure that no call is allowed to violate the consistency of the
topic map. Persistent implementations might also want to store a flag that
indicates whether or not a particular TopicMap object should be wrapped in
the consistency-enforcing layer.
I think that there is room for / need for both of these approaches - The
tradeoff as I see it is that (2) eliminates a lot of the freedom and
flexibility of TM4J (particularly in the dynamic merging), so simply making
the core API enforce consistency is not an option IMHO; whereas (1) is
nice as it only enforces consistency at the point of use, but it is
extremely processor intensive (though additional indexing layers could
probably improve this) and so is not really a viable alternative when
dealing with large topic maps in a persistent store.
I would like to hear others thoughts
Cheers,
Kal
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