Re: Record syntaxes and schemas - XML, Dublin Core, etc

Alan,

I agree that solution 1 is the theoretically correct approach. I think it's 
also mandated by the holdings "profile"... I've been using schemaIDs a bit 
lately against various types of systems, so it's definitely seeing 
implementation among v3 implementations... lots of old v2-based library 
servers don't support (obviously) CompSpec, but then these servers are not 
likely to be returning XML records anyway, so it's a small loss.

However, I also think that within the scope of a profile or other bilateral 
arrangement, it is quite reasonable to use an element set name to carry the 
same information. It seems to me that logically, an element set name 
should, by agreement, be able to identify any old combination of CompSpec 
parameters, inclusive a schema.

--Sebastian

At 11:35 13-03-2002 +1100, Alan Kent wrote:
>A question came up in my mind on a different list, but its a Z39.50 issue
>so I will ask it here. Its probably a theory versus practice question.
>I think I know the correct theoretical approach as defined by Z39.50,
>but in practice I don't know if anyone uses it, currently supports it,
>or is likely to support it - so does that make it the wrong way to go?
>Its an old issue by the way.
>
>Problem: I have a database of XML documents. I want to be able to ask
>for records to come back as the full document (marked up in XML) or as
>dublin core metadata (again, marked up as XML).
>
>There are 3 solutions that come to mind. Comments appreciated (yes,
>no, screams of anguish, that sort of thing).
>
>Solution 1:
>I think the theoretically correct approach is In present requests, use
>recordComposition of 'complex', then in the 'Specification' type specify
>the optional schema OID along with the element set names. The schema OID
>would be different for the two forms of XML, but the record syntax OID
>for both would be the XML record syntax.
>
>The only problem I have with this is that it requires version 3 of
>the protocol, and who actually supports it? How many clients support
>it? I can see that preferred record syntax OIDs and element set names
>can be programmed, but not schema OIDs. This may be because many clients
>are still V2 for example.
>
>Solution 2:
>Allocate a new record syntax OID for Dublin Core in XML. This might
>be done by adding a new digit on the end of the XML OID. That is,
>all OIDs starting with the XML OID must be XML. 1.2.840.10003.5.109.10
>is for generic XML, and 1.2.840.10003.5.109.10.1 is for Dublin Core etc.
>The advantage is most clients can be configured to choose a record syntax
>OID.
>
>Solution 3:
>Use the XML record syntax OID, but rely on usage of element set names.
>That is, introduce standard element set names for 'DC-B', 'DC-F' etc.
>
>I am interested in both theory and practice. It has come up for me
>personally with respect to ZiNG/SRW and translating SRW arguments
>into Z39.50 requests. Its particularly a problem for my implementation,
>as while our server has implement lots of Z39.50 (explain, extended
>services, v3, concurrent operations, resource reports, multiple record
>syntaxes etc), the one area we have not done anything to date is schemas.
>And if no clients (or even most), then I have a quandry of doing
>"the right thing" (which could be a lot of work) or "something that
>is practical and is interoperable".
>
>Feedback appreciated.
>
>Alan
>--
>Alan Kent (mailto:ajk@mds.rmit.edu.au, http://www.mds.rmit.edu.au)
>Postal: Multimedia Database Systems, RMIT, GPO Box 2476V, Melbourne 3001.
>Where: RMIT MDS, Bld 91, Level 3, 110 Victoria St, Carlton 3053, VIC 
>Australia.
>Phone: +61 3 9925 4114  Reception: +61 3 9925 4099  Fax: +61 3 9925 4098

--
Sebastian Hammer, Index Data <http://www.indexdata.dk/>
Ph: +45 3341 0100, Fax: +45 3341 0101

Received on Thursday, 14 March 2002 18:03:30 UTC