Dear WG Members,
Since DC2001 there has been a significant amount of work completed towards
our goal of an operational registry. I would like to summarize some of what
has been accomplished.
Two prototypes were demonstrated at DC2001, one built on the EOR toolkit
[1], the other an in-memory application. Both of these were useful for
demonstrating registry functionality and evaluating technology solutions,
but neither proved suitable as a basis for an operational registry.
Prototype 1 did not perform as well as expected, and sported an outdated,
forms-base user interface. Prototype 2 was considered unsuitable due it's
lack of persistent data store and limited search functionality.
A third prototype has since been written. It is based on the Jena toolkit
[2] and incorporates much of what was learned from the previous prototypes.
Jena is a functionally-rich API for processing RDF data. This prototype
uses a BerkeleyDB [3] database as a persistent data store. I am very
excited about this combination of technology. Jena and BerkeleyDB deliver a
powerful set of functions for processing RDF schemas, and at performance
levels that rival in-memory processing. That is the good news. The bad
news is that the interface between Jena and BerkeleyDB is not 100% stable
and can result in unexpected system failures. The Jena developers are
working on the problem but are unable, at this time, to commit to a date
when it will be fixed.
As a result of the Jena-BerkeleyDB problem just described the operational
registry will be developed using Jena, with a PostgreSQL database for a
persistent data store. Performance will not be quite as good as what we
would achieve with BerkeleyDB, but is still well within the acceptable
range, and more importantly, without the stability problems. Additionally,
the source code changes required to switch from BerkeleyDB to PostgreSQL are
minimal, which will allow us to change back to BerkeleyDB once the stability
problem has been resolved.
All three of the prototypes, and the work to-date on the operational
registry are accessible at: http://wip.dublincore.org:8080/registry/Registry
Please note that the operational registry (the link labeled DCMI Registry)
will evolve as functional requirements are finalized, and, as much as
possible, will reflect the current consensus of the WG.
As always, your comments, suggestions, etc. are welcome.
Best Regards,
Harry Wagner
OCLC / DCMI
Dublin, OH 43017
(614) 761-5178
mailto:[log in to unmask]
[1] http://eor.dublncore.org
[2] http://www.hpl.hp.com/semweb/jena-top.html
[3] http://www.sleepycat.com/
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