Re: Semantic Web User Agent Conformance

On 22/11/2007, Sean B. Palmer <sean@miscoranda.com> wrote:

> I'm proposing some kind of work on conformance levels for Semantic Web
> User Agents, such that when someone says "how many triples are in
> $uri", we can answer confidently "a Class 2 Semantic Web User Agent
> will return 53 triples"; or perhaps not *that* abstract, but along
> those lines.

While I generally like the idea of checks like this, it seems there
might be problems both in practice & in principle.

In practice...ok, for example let's say I say my doc uses hTurtle, but
due to circumstances beyond anyone's control the profile doc 404s. A
lot less triples.

In principle, well firstly I feel a little uncomfortable with the
implication that an agent needs to provide a given level of
conformance. A big benefit of the kind of data we deal with is that
the producer can publish what it likes, the consumer can pick & choose
what it likes.

But being marginally more concrete, how might one go about pinning
down the association between a resource and its representation as a
single (named?) graph to the extent necessary to inspire confidence?
Take a case like an RSS 1.0 blog feed. Yesterday it contained 100
triples, today it contains 100 triples. Different triples each day,
yet both presumably constitute a legit representation of the resource
in question. (Along with whatever triples are expressed in any
different representations - GRDDL, RDFa etc, which may or may not
coincide with those in the feed).

It seems to me that formal conformance levels are too strong in this
context, way beyond the kind of thing e.g. the RDF Validator and
Vapour offer. There's obvious benefit in testing tools like those
mentioned recently in the validation thread, but I'm not sure how
deterministic a given chunk of web clients/servers can be (and it will
be a chunk if we consider GRDDL's profile chaining).

Consider a Semantic Web cache, which for practical reasons doesn't
accumulate every triple it encounters. The view to the agent may
sometimes differ significantly from the current data available at the
other side of the cache. Is this a legitimiate component on the
Semantic Web? How does it /really/ differ from say an RDF/XML file
served on the Web? Will that file as seen by a consumer always exactly
reflect the producer's intended truth?

Dunno, although I like the sound of conformance levels within a very
local context (and Draconian format checking etc), more generally my
gut feeling is that a better test of a SWUA is how resilient/useful it
is in circumstances of limited (c.f. danbri's "missing isn't broken")
and even unreliable information.

Cheers,
Danny.

-- 

http://dannyayers.com

Received on Tuesday, 27 November 2007 21:00:05 UTC