[OAI-implementers] OAI-PMH baseURL discovery

[Andy Powell]

On Mon, 14 Feb 2005, Michael Nelson wrote:

> > I disagree with your implied preference for using <meta> rather than
> > <link>.  In this case, we clearly want to provide a link to another
> > resource - therefore the semantics of the <link> tag are much more
> > appropriate than the semantics of the <meta> tag.
> >
> > I also suspect that your suggested use of
> >
> > OAIPMHbaseURL="..."
> >
> > and
> >
> > OAIPMHrecord="..."
> >
> > break the (X)HTML specs (though I haven't checked)?
>
> you are correct -- they do.
>
> re: meta vs. link...  We don't have a strong opinion either way, but I did
> see this:
>
> http://www.w3.org/TR/2004/WD-xhtml2-20040722/mod-meta.html#sec_20.5.
>
> "This element defines a link. Link conveys relationship information that
> may be rendered by user agents in a variety of ways (e.g., a tool-bar with
> a drop-down menu of links)."
>
> I know <link> is not in common use, but it appears like the intention is
> to promote it to interactive user status?  If so, wouldn't that be the
> wrong thing to do with a (for example) GetRecord request?

Possibly, though I note that the same document also says this in section
20.2.2

 Note that just because we are using URIs as unique identifiers doesn't
 mean that navigating to this URI with a web browser would yield anything
 useful.

which doesn't seem entirely compatible with the section you quote from!

Remember that this document is about XHTML 2.0, which is not finalised.

On the other hand, section 5.19 of

http://www.w3.org/TR/xhtml-modularization/

(which I think is the appropriate W3C recommendation) says

 The Link Module defines an element that can be used to define links to
 external resources. These resources are often used to augment the user
 agent's ability to process the associated XHTML document.

which doesn't (to me) imply that the browser should necessarily expect to
display the <link> to the end user (i.e. "augment" could mean other
things).  In our case, the 'user agent' is a Web robot, which is being
'augmented in its ability to process the document' by being pointed to the
OAI repository (or specific OAI record)  associated with the page.

Having said that, I know that some browsers do display all <link> tags to
the end-user in some form (e.g. Lynx and Opera I think).  This has
resulted in a couple of negative comments about one of the DCMI
recommendations ("Encoding DC metadata in (X)HTML meta and link
elements").  Dublin Core recommends using a <link> tag to provide the
namespace URI associated with the "DC." prefix used in <meta> tags like

<meta name="DC.title" content="blah" />

and I know that a couple of people have complained that their browsers
show them the namespace URI as though it is a clickable link :-(

All in all I'm not sure what is best.  I think that the semantics of
<link> are appropriate, but given some browser behaviour it may be more
sensible to use <meta>.

Andy
--
Distributed Systems, UKOLN, University of Bath, Bath, BA2 7AY, UK
http://www.ukoln.ac.uk/ukoln/staff/a.powell/      +44 1225 383933
Resource Discovery Network http://www.rdn.ac.uk/