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Re: Requesting XML records via Z39.50

From: Ray Denenberg <raydenenberg@starpower.net>
Date: Tue, 19 May 2009 16:30:27 -0400
Message-ID: <320701c9d8c0$a5c2fe70$18af938c@lib.loc.gov>
To: "Tommy Schomacker" <TS@dbc.dk>, <www-zig@w3.org>
Tommy - Yes, I agree completely.   Sorry this has slipped and thank you for 
bringing it back up. I just spent some time reviewing the entire discussion 
on this.

I agree that we do not need to continue to assign OIDs for every schema, and 
that in the typical case the schema identifier used for SRU should also be 
used for Z39.50.  There may still be cases where OIDs need to be used and we 
can treat them as special cases.

The remaining question is what will SRU use for schema identifiers, as there 
is currently discussion about aligning SRU andOpenURL identifiers. But I 
expect that discussion to be resolved quickly.

In any case, we can revise the agreement to reflect this.

--Ray


----- Original Message ----- 
From: "Tommy Schomacker" <TS@dbc.dk>
To: "Ray Denenberg" <raydenenberg@starpower.net>; <www-zig@w3.org>
Sent: Tuesday, May 19, 2009 9:39 AM
Subject: SV: Requesting XML records via Z39.50


Hello Ray et al,

It seems like this topic got into a dead end. I still think we need a 
revision of the implementor agreement "Requesting XML Records" from August 
2003. The scope of the agreement should be, not to exclude any of the 
existing ways, but to describe the various ways used to specify the schema, 
and to draw the relation between Z39.50 and SRU - as you have already done 
in mails.

The future will bring a lot of XML schemas to be handled by Z39.50 and SRU, 
and it would be nice if the same schema identifier could be used in both 
protocols. The method using the common OID 1.2.840.10003.5.112 (XML-b), as 
the record syntax, and supply a globally unambiguous identifier of the 
desired XML definition as the element set name (e.g. an URI) will serve this 
purpose. Defining an OID for each schema and subschema is foolish.

I hope you agree.

Best regards
Tommy Schomacker
-----Oprindelig meddelelse-----
Fra: www-zig-request@w3.org [mailto:www-zig-request@w3.org]På vegne af
Tommy Schomacker
Sendt: 9. marts 2009 15:16
Til: Ray Denenberg; www-zig@w3.org
Emne: SV: Requesting XML records via Z39.50


I suggest we document the 112-method in an implementer's agreement :-)
/Tommy
-----Oprindelig meddelelse-----
Fra: Tommy Schomacker
Sendt: 9. marts 2009 13:26
Til: 'Ray Denenberg'; www-zig@w3.org
Emne: SV: Requesting XML records via Z39.50


We use compSpec in one of our applications, but we will be able to a single 
URI-based form for future applications.
/Tommy
-----Oprindelig meddelelse-----
Fra: www-zig-request@w3.org [mailto:www-zig-request@w3.org]På vegne af
Ray Denenberg
Sendt: 30. januar 2009 00:11
Til: www-zig@w3.org
Emne: Re: Requesting XML records via Z39.50



I agree that using a single form of the schema identifier is preferable, and
that it should be the URI form as used in SRU.

If there is anyone who objects?

If we do that then I would want to cease registering OIDs for new schemas.
We can do that only if nobody is using copmSpec.

So ... is anyone out there using compspec?

--Ray



----- Original Message ----- 
From: "Tommy Schomacker" <TS@dbc.dk>
To: "Adam Dickmeiss" <adam@indexdata.dk>; "Ray Denenberg"
<raydenenberg@starpower.net>
Cc: <www-zig@w3.org>
Sent: Thursday, January 29, 2009 4:01 AM
Subject: SV: Requesting XML records via Z39.50


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
>
>
>
>
>
>
Received on Tuesday, 19 May 2009 20:31:04 GMT

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