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RE: Attaching (embedding?) RDF

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Tue, 28 Oct 2003 10:57:45 +0100
To: "Martin May" <maym@foobar.lu>, "Rahul Singh" <kingtiny@cs.cmu.edu>
Cc: <www-rdf-interest@w3.org>
Message-ID: <BHEGLCKMOHGLGNOKPGHDKECMCCAA.jjc@hpl.hp.com>


A workable hack on the embedding front (option 3) is to do a linear search
of the file for the rdf:RDF tag, ideally this needs to be smart i.e. a
search for
"<" + NCName + ":RDF" + whitespace + other xml attributes + "xmlns:" +
NCName + whitespace + "=" + whitespace + ["'] +
http://www.w3.org/rdfnamespaceuri# +["'] + other xml attributes + ">"

One needs to assume UTF-8 or UTF-16 encoding.

A linear search for the namespace uri can be quite efficient (I don't have
the reference for the technique for searching for a long fixed substring,
but you only have to look at a few of the characters). You then need to work
back from there to see if the rdf:RDF matches.

The idea is that at first approximation all embeddings are the same and one
doesn't need to know the master file type.

Jeremy

> -----Original Message-----
> From: www-rdf-interest-request@w3.org
> [mailto:www-rdf-interest-request@w3.org]On Behalf Of Martin May
> Sent: 27 October 2003 20:14
> To: Rahul Singh
> Cc: www-rdf-interest@w3.org
> Subject: Re: Attaching (embedding?) RDF
>
>
>
>
> Yes,
>
> I actually looked at XMP, and it seems that they are using method #3
> (please correct me if I'm wrong). IMHO the drawback of not being able
> to store metadata in a generic way and having to write custom adaptors
> for every file type is quite a big one. On top of that, some file types
> don't support embedded metadata at all.
>
> I was hoping that somebody would know of some alternatives to the ones
> that I presented or know of methods to overcome the drawbacks.
>
> Thanks,
>
> Martin
>
> On 27 Oct 2003, at 18:43, Rahul Singh wrote:
>
> > Have you looked at Adobe XMP?
> >
> > http://www.adobe.com/products/xmp/main.html
> >
> > Cheers,
> >
> > Rahul
> >
> > Martin May wrote:
> >
> >>
> >>
> >> I would like to attach RDF metadata to files. So far I have
> >> identified the following options for doing so, all of which have
> >> drawbacks:
> >>
> >> 1. given a file foo.pdf, store the metadata in a file foo.pdf.rdf in
> >> the same directory
> >>
> >> Main drawbacks:
> >>
> >> - if the file is moved or renamed, the metadata must be moved with it
> >>
> >> 2. store the metadata in a central repository, with a link (URI) to
> >> the file
> >>
> >> Main drawbacks:
> >>
> >> - again, if the file is moved or renamed, the link becomes invalid
> >> - requires a central repository
> >>
> >> 3. embed the metadata in the file format
> >>
> >> Main drawbacks:
> >>
> >> - doesn't work with every file type
> >> - different handling for each file type required
> >>
> >> 4. create an archive file which groups the file and its metadata
> >> (e.g. jar)
> >>
> >> Main drawbacks:
> >>
> >> - requires unpackaging and repackaging every time the file needs to
> >> be accessed
> >>
> >> Does anybody have any insights or ideas on how to improve the
> >> suggested methods, or provide me with other alternatives?
> >>
> >> Best regards,
> >>
> >> Martin May
> >> University of Aberdeen
> >>
> >>
> >
>
>
Received on Tuesday, 28 October 2003 04:59:13 GMT

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