Print

Print


Dear Ray,

thanks a lot for the explanation. These are all good reasons for you
doing so, however that still doesn't solve the problem that mods is
simply incompatible with other schemas which import from the original
location if a more or less strict validator/parser is used.

Have you ever thought about adjusting the namespace so that it actually
uses a custom one? (you can argue if that is correct since it is just a
second workaround, but in your case it would greatly improve the
interoperability with other schemas).
If xlink is a custom version, I think it would be even more correct to
use a different name space there.

After all importing different schemas into the same namespace is often
not supported because for many parsers the same namespace means the same
schema location (AFAIK the behavior for different schemas imported into
the same namespace is undefined by the standard). If the parser is
graceful and tries to parse both schema locations it will result in
errors complaining about re-defined elements (because your schema is not
an addition but a copy).

Best wishes,
Wolfgang


Ray Denenberg, Library of Congress schrieb:
> The xml.xsd question is more easily answered. Several years ago we were
> forced to find a way to reduce the number of MODS accesses to the W3C
> server. The reason was that W3C was complaining (loudly) about excessive
> accesses and threatening to block certain clients. Someone was not properly
> caching xml.xsd and was in addition validating an inordinate number of MODS
> records.  This happened a number of times, we were unsuccessful at tracking
> down the culprit, and as a quick fix changed the reference to LC rather than
> W3C, and the problem has not resurfaced. 
> 
> Xlink is more complicated, although you could use the same justification,
> even if there weren't additional complications. In the Xlink case, the W3C
> version simply didn't meet MODS requirements.  I can't recall exactly why,
> I'm tracking that down, and I'll get back to you (but I wanted to respond
> quickly to the question).
> 
> --Ray
> 
>> -----Original Message-----
>> From: Metadata Object Description Schema List
>> [mailto:[log in to unmask]] On Behalf Of Wolfgang Koller
>> Sent: Monday, March 21, 2011 4:53 AM
>> To: [log in to unmask]
>> Subject: [MODS] Problems with Import(s)
>>
>> Dear all,
>>
>> I'm currently working on a schema which uses MODS to track the
>> bibliographic information of an element.
>> However, unfortunately, there are several critical imports in MODS
>> which heavily conflict with other schema which try to import into the
>> same namespace (multiple definitions of the same attributes / elements).
>>
>> Unfortunately MODS uses its own copy of the xml.xsd schema and the
>> xlink.xsd schema.
>>
>> - As far as I found out, the xlink schema is a separate & modified
>> version of the original xlink schema which can be found at
>> http://www.w3.org/1999/xlink.xsd. However from my point of view, it is
>> heavily dangerous to customize a schema but import it into the same
>> namespace then. I would recommend defining a own namespace for your
>> custom schemas (even if they are based on an "official" schema).
>>
>> - The same applies for the xml.xsd schema (the official version can be
>> found at http://www.w3.org/2001/xml.xsd). However there I did not find
>> any difference in the official and the version hosted by loc - what's
>> the reason for hosting it own your own?
>>
>> Is there any chance that you are going to update mods and reference the
>> official schemas and/or change the target namespace so that mods can be
>> combined with others schemas trying to import the official ones?
>>
>> Best wishes,
>> Wolfgang
>>
>> --------------------------------------
>> Information gemaess UGB Par. 14 Abs. 1
>>
>> Naturhistorisches Museum
>> 1010 Wien, Burgring 7
>> Firmenbuchnummer: FN 236724z
>> Firmenbuchgericht: Handelsgericht Wien
>> UID: ATU 38020609
>> Rechtsform: Wissenschaftliche Anstalt
>> oeffentlichen Rechts des Bundes
>> --------------------------------------

--------------------------------------
Information gemaess UGB Par. 14 Abs. 1

Naturhistorisches Museum
1010 Wien, Burgring 7
Firmenbuchnummer: FN 236724z
Firmenbuchgericht: Handelsgericht Wien
UID: ATU 38020609
Rechtsform: Wissenschaftliche Anstalt
oeffentlichen Rechts des Bundes
--------------------------------------