[OAI-implementers] ABOUT & Schemas & metadataPrefix

herbert van de sompel herbertv@cs.cornell.edu
Mon, 02 Apr 2001 12:07:54 -0400

Tim Brody wrote:

> >From a harvesters point of view (I don't believe there are many of us :-), I
> would prefer to have "oai_dc" because that tells me explicitly what data I
> can expect to find, rather than having to remember what I requested (as far
> as I can tell it is the one part that makes an isolated OAI response
> stateful, a real pain if one is using caching or other systems).

The metadataPrefix is only signficiant within the realm of a certain
repository.  The only exception is the metadataPrefix oai_dc, which --
by convention -- refers to metadata expressed in unqualified Dublin Core
in all repositories.  

Regarding the metadata that flows back to the harvester in response to a
protocol request: 

* what REALLY tells you which metadata you receive is the namespace:
xmlns="http://purl.org/dc/elements/1.1/" .  that is a global identifier
of the format.

* in addition to that, you do not have to "keep" the format you asked
for: all response are self-contained, meaning you can tell from the
original protocol request -- which is the content of the requestURL
element -- what you asked for.  this has been a deliberate choice, since
we are indeed talking about robots harvesting metadata, and some
software processing the harvested metadata at a later stage.



Herbert Van de Sompel
Visiting Assistant Professor
Cornell University -- Computer Science
tel + 1 - 607 - 255 - 3085
fax + 1 - 607 - 255 - 4428
digital life in libraries used to be primitive