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Re: "Z39.50 Server List" DTD

From: Rob Bull <bull@crxnet.com>
Date: Wed, 21 Jun 2000 19:24:49 +0000 (GMT)
To: John Robert Gardner <jrgardner@atla-certr.org>
cc: Robert Waldstein <wald@LIBRARY.HO.LUCENT.COM>, www-zig@w3.org
Message-ID: <Pine.GSO.3.96.1000621191904.5109A-100000@popeye>
John,

in the European Commission funded project ONE (OPAC network in Europe) the
project partners did a lot of work on Explain - it ran in parallel with
the "ZIG Explain working group".  We recognised the benefit of using
explain, but at the end of the day, in incurs quite a lot of overhead
 - not just at the toolkit level, but the application development is 
quite significant; there is a connection overhead level (possibly
optimised by caching); and for data providers there is an administrative
overhead to consider as well in keeping the data up to date.

The ONE project did in fact deliver an explain database toolkit for free -
OK, its a bit oriented towards our Z39.50 toolkit, but not impossible to
adapt to other toolkits.  

Now, in the follow up ONE-2 project, we have re-visited explain again, and 
(I guess to your dissapointment) invented "another work round" we call
explain-lite - its a piece of XML passed on Init.

However, this has been created for real reasons -
- it is considered that creating an XML approach is far more in line with
21st century technology, rather than the overhead of the explain PDUs,
- it covers the _real_ things people want to know about a server, and not
the additional baggage that you can get with explain;
- such XML can be used in conjunction with other means of disseminating
information about a server - for instance, the very same XML could be
published on a web page - this saves administration effort etc.
- the effort in creating a tool for managing data in an explain database
is quite significant, you cant assume a Z39.50 expert/programmer to be
available for maintaining such data;
- tools in the XML world are available now that can be used to parse the
validity of such explain data, these tools deal with related
issues such as character sets etc. that would probably be otherwise hand
coded.

I'm not against the Z39.50 explain service at all - I participated in the
explain working group, spent many hours coding explain in our ICONE
client, and we spent considerable hours creating our explain database
freeware kit. The reality is that probably less that 1% of servers use
explain.

Rob
Received on Wednesday, 21 June 2000 14:33:18 GMT

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