[OAI-implementers] Reconsidering mandatory DC in OAI-PMH

Jose Borbinha jose.borbinha@bn.pt
Tue, 5 Aug 2003 10:22:50 +0100

I full agree with this direction!
We, at the National Library of Portugal (BN), are an example of that
case! We have been using OAI-PMH for several purposes, and we'd like to
expand that usage, as for example for the transport of UNIMARC Authority
records (which have no straight mapping to the DCMES).

On the other side we'll need to be carefull to avoid mess. If everyone
starts publishing metadata using his/her own schema (even when they
claim to be using MARC21 or UNIMARC, sometimes people make very strange
data...), the risk of loosing interoperability can be high. But this is
just going back to the real world, I guess :)

To deal with that we could do a few thinks, IMHO:

- We could discuss the design and development of a new kind of service,
which we could call of "metadata schema verifier (MSV)". These could be
services that data providers could use before the release of their
server, to check their metadata (the structure, not the smantics, off
course). A MSV for UNIMARC, for example, would act as a service
provider. It'd get the data from a data provider, check its structure
against the official standard, and produce a report to be delivered to
the data provider.
The OAI community could define and design these services, and invite
each relevant agency/entity in charge of a schema to support an
implementation for its case.

- Another interesting service to the community could be the publishing,
in the OAI reference site, of XSLT transformations of the non-DC
metadata schemas to DC, when possible and when it'd make sense. The
perfect scenario would be the possibility to "plug" those
transformations in the OAI clients, and use them when desired. This
would make it possible for a data provider to publish the metadata in
its own schema X, send it like that to a service provider, but on this
side it could be immediatly transformed to DC by the client, if desired,
just like if it were published in DC. I'm not sure if this will really
work 100%, but at least for the more common standards it might work

- Finally, the previous two scenarios could be related with a
registration service for the no-DC schemas. This could consist in the
registration of the MSV service and the "XSLT for DC" in the OAI site,
which would result also in the reservation of the respective

Does this make sense? Not too complicate?

We can do this for UNIMARC at BN...

Josť Borbinha
National Library of Portugal

-----Mensagem original-----
De: oai-implementers-admin@oaisrv.nsdl.cornell.edu
[mailto:oai-implementers-admin@oaisrv.nsdl.cornell.edu] Em nome de Carl
Enviada: segunda-feira, 4 de Agosto de 2003 20:49
Para: oai-implementers@oaisrv.nsdl.cornell.edu
Assunto: [OAI-implementers] Reconsidering mandatory DC in OAI-PMH

Dublin Core has been the mandated metadata format in OAI-PMH since the
initial release of the protocol. The purpose of this requirement was to
promote interoperability among data providers. It was the subject of
considerable discussion in the formulation of both the 1.0 and 2.0
specifications and we think that it is time to reexamine this
requirement in light of two factors:

1. There is increasing interest in using the protocol for applications
other than sharing metadata to promote resource discovery [1][2]. Dublin
Core is targeted mainly as metadata for resource discovery and is,
therefore, inappropriate for these other applications.  It might make
sense to loosen the Dublin Core requirement to a recommendation, and
thus reduce any barrier to these broader applications.    

2.  The linkage between Dublin Core and OAI-PMH has been over-emphasized
at the expense of the utility of OAI-PMH for dissemination of richer,
and perhaps more useful, structured data.  In some cases data providers
with richer metadata (e.g., MARC, IEEE LOM) have been forced by the
requirement to dumb-down rich metadata to Dublin Core and have then
failed to provide the original metadata.  As a result, the community
looses the benefits of rich data and is left with the reduced semantics
of Dublin Core.

We need to choose between the competing goals of protocol stability and
generalization.  Although removing the Dublin Core requirement would not
negatively impact existing or future data providers, it may impact
service providers whose applications depend on the existence of a
uniform metadata format.

We would like to open this subject for community discussion. While the
technical aspects of this change are minimal it does have considerable
political impact. Please give your feedback on the following proposal:

1. Change the Dublin Core requirement to a recommendation.
2. Leave oai_dc as a reserved metadataPrefix
3. Move the oai_dc part of protocol document to Implementation

We invite members of this list to contribute their thoughts on this. 

[1] http://www.dlib.org/dlib/july03/young/07young.html

Carl Lagoze
Michael Nelson
Herbert Van de Sompel
Simeon Warner

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