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SV: Requesting XML records via Z39.50

From: Tommy Schomacker <TS@dbc.dk>
Date: Thu, 29 Jan 2009 10:01:04 +0100
Message-ID: <AECD8A56E2F97346BD62A728355A9262D99D77@dbcmail.dbc.dk>
To: "Adam Dickmeiss" <adam@indexdata.dk>, "Ray Denenberg" <raydenenberg@starpower.net>
Cc: <www-zig@w3.org>

Thanks to Ray for the excellent description of the problem and for trying to find a solution.

First and most important. We need a clear specification on how to deal with xml schemas and subschemas in Z39.50 and ind SRU. I think Rays proposal meets this goal.

Second and also important. It would be nice if the schema identifiers registered for Z39.50 could be valid for SRU too - and vice versa. I think Rays proposal also will meet this goal if we use URI instead of OID.

Do we need to take compspec into consideration? As I understand it, this is not used very much and it has no counterpart in SRU.

Best regards
Tommy Schomacker, Danish Bibliographic Centre
-----Oprindelig meddelelse-----
Fra: www-zig-request@w3.org [mailto:www-zig-request@w3.org]På vegne af
Adam Dickmeiss
Sendt: 29. januar 2009 09:10
Til: Ray Denenberg
Cc: www-zig@w3.org
Emne: Re: Requesting XML records via Z39.50



Ray Denenberg wrote:
> From: Adam Dickmeiss [mailto:adam@indexdata.dk] 
>   
>> It's also been our assumption that it would be practical to use same schema
>>     
> identifiers for both SRU and Z39.50. Why have two registries? 
>
>
> Well the problem is that you have to use the OID form if you are supplying
> the schema identifier in the schema field in compspec. 
Well. the way I read amendment 5, the schema OID became optional.
http://www.loc.gov/z3950/agency/amend/am5.html
A string , member uri, may be given instead.

The CompSpec has recordSyntax in it and that is required.  But that's 
not a schema.. So using Amendment 5 we have a way to specify a string 
based schema.. Now all this is probably not of interest to many since 
it's not widely used, AFAIK.

The element set way.. Page
http://www.loc.gov/z3950/agency/agree/request-xml.html
mentions schema identifiers.. This page even has link to the SRU record 
schema identifers.. Although the link no longer works.

My only hope was both that both SRU and Z39.50 would use the same schema 
identifiers for XML. Z39.50 has OID based syntax and of course SRU has 
recordPacking (but that doesn't affect the schema identifiers).

> You don't have any
> choice there because it's typed as asn.1 OBJECT IDENTIFIER. True, you could
> (technically) use the URI form when supplying it within the element set name
> parameter (because it has no such restriction).  So one way or the other you
> end up with two different identfiers: either (a) different for SRU and
> Z39.50, or (b) different for the two ways within Z39.50. And in the second
> case, one of the two will be inconsistent with SRU.  So (a) would be the
> lesser of the evils, wouldn't it?
>
> (Or are you suggesting that we use OIDs instead or URIs in SRU. I hope not.)
>   
Of course not.

/ Adam
> --Ray
>
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>   
Received on Thursday, 29 January 2009 09:01:52 GMT

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