requesting XML records

We need an agreement among Z39.50 implementors on
how to request xml records.  This is, in
particular, an urgent issue for Bath profile
implementors.

There was discussion of this a few months ago on
the Bath list. There was no consensus ( I do think
however that there was *near*-consensus),  and
unfortunately the discussion never made it to this
list.

I want to summarize the discussion and offer a
proposal.

To frame the question: Let's assume (hopefully
without too much loss of generality) we want to
request DC records. We assume we want them in XML
(so the record syntax is xml, i.e.
1.2.840.10003.5.109.10); How do we indicate DC?

One suggestion is to assign object identifiers
subordinate to 1.2.840.10003.5.109.10.  This idea
has a number of disadvantages and unless someone
wants to pursue this approach I'd prefer to
discard it.

Another approach is to indicate the schema using
comSpec.  This idea didn't catch on because many
of the interested parties want a solution that
will work with version 2.

Yet another approach is to use the element set
name parameter to indicate the schema.  Actually,
this is pretty much what we agreed upon in
principle at the last ZIG meeting (nearly a year
ago). But we didn't think this through carefully
enough.  Do we mean a schema, or a  namespace?  On
one hand, there isn't really a unique uri for a
schema, hence the suggestion to use a namespace
uri;  on the other hand there isn't always a 1-1
correspondence between a schema and namespace
(usually, but not always).

That's my attempt to summarize the issue. My
proposal is to adopt the approach used by SRW when
faced with a similar problem. For the esn, use a
URI that serves as an identifier for the desired
schema (you don't have to call it a namespace).

Look at
http://lcweb.loc.gov/z3950/agency/zing/srw/records.html
the first table. It says in effect, if you want to
indicate DC, use the URI
http://www.loc.gov/zing/srw/dcschema/v1.0/ to
identify it (you will be identifying the schema at
www.loc.gov/zing/srw/dc.xsd).  If you want to
identify MODS use http://www.loc.gov/mods/.  Etc.

I understand the weakness of this approach, it
won't scale well if we have thousands of schemas,
but at the moment we don't, and we need a simple
and quick solution.

--Ray

Received on Tuesday, 25 March 2003 14:38:43 UTC