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Re: Semantics of objects in UDD : seeking more standardization, interoperability ?

On Thu, Feb 12, 2009 at 06:00:38PM +0100, Olivier Berger wrote:
> (message about UDD, CC-ed to qa list, although I'm not so sure it
> belongs here)

It does belong here. At the end of the SOC which firstly developed
UDD, we proposed to use -qa as the forum for UDD-discussions and
nobody objected. Also, IIRC, -qa is the contact point for UDD
mentioned on wiki.d.o (can't check, because I'm writing while

> I've just already responded (Message-Id:
> <1234456666.7959.46.camel@hortense>) to Enrico Zini on d-d@l.d.o
> about the lack of semantics (in the sense of Semantic Web standards
> used to convey ontological references, like RDF schema, etc.) in the
> outputs of DDE, so this message's subject is quite similar.
> I guess the same kind of criticism indeed transitively applies to
> UDD (DDE exports UDD data, IIUC).

So I guess I should reply in the same vein :-), that the criticism
does not apply here either. More precisely, it does not apply *inside*
UDD, but nothing forbids you to develop a semantics for UDD (in
whatever language you want, web-ontologies being just one of the
possibilities) externally to it. Actually, I'm also personally
interested in doing that, even though I insist that it is not
something that should be added *inside* UDD.

> I have written a short piece on the subject
> (http://www-public.it-sudparis.eu/~berger_o/weblog/2009/02/10/udd-swim-flossmetrics-facts-databases-about-libre-software-distributions-going-semantic/)
> after the FOSDEM, and I'd like to get your comments on these ideas.

Sorry but I don't have the article with me, but I will reply as soon
as I've a chance to read it.

> Of course, more semantics may not be necessary from the strict
> immediate needs of Debian-specific tools. But I imagine that using
> standard representation formats (for the same semantics of similar
> objects), QA tools could be "ported" from distributions to other
> distributions, and eventually manage inter-distributions data.

That's the essence of my reply to your DDE criticism: semantic is
surely needed for interoperability, but rarely (with exceptions!) for
internal purposes. That's why I believe we should piggyback semantics
on top of UDD yet externally, instead of internally into it.

Now, back to how do that, I believe the main problem you will face is
how to identify the objects in UDD, given that they potentially change
daily and they don't have URIs identifying them. I see various
possibility to achieve that, the first one is for you to develop some
URI scheme which internalizes the keys used inside UDD.

For example, to reference a binary package for a specific arch, you
can use some URI scheme containing binary package name, version, and
architecture. You should do something similar for all keys of all
packages (maybe you can come up with a generic URI scheme also
including the UDD relation name?).

Alternatively, we can think together at URIs uniquely identifying
tuples in each UDD table, and add an extra URI field to each such
table. De facto, such new field will be a new key for the table, and
you can use it to state facts (i.e., "triples" in the RDF lingo) about
such objects.

I tend to prefer the latter option, how about you?


Stefano Zacchiroli -o- PhD in Computer Science \ PostDoc @ Univ. Paris 7
zack@{upsilon.cc,pps.jussieu.fr,debian.org} -<>- http://upsilon.cc/zack/
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