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2005-06-28

More on RSS "extensions"

First it was Microsoft's announcement regarding RSS, and now Apple has released its iTunes-specific RSS extensions. Edd Dumbill's analysis is interesting.

Posted by ora at 13:09

2005-06-26

RSS in Longhorn

It seems that I am into conspiracy theories lately...

Microsoft has announced that they will provide "extended" RSS support in Longhorn. OK, fair enough. RSS is a "Good Thing" (in general, although personally I am not happy about the divergence of RSS specifications and only provide RSS 1.0-formatted feed of this blog).

Now, I tried reading Microsoft's specification for "Simple List Extensions". Is it just me, but this - rather simple - specification took me a disproportionate amount of time to understand (this implies that I did understand it, although I am not quite sure now).

I think Danny Ayers got it right when he said that "those who forget RDF are destined to reinvent it…eventually". This reminds me of something that happened a long time ago at the first W3C Query Languages workshop: I went to talk to Microsoft's Adam Bosworth after his presentation and told him that I pretty much agreed with what he had said. He was surprised; I suppose he may not have realized that in his presentation he had proposed "extensions" to XML that made it look a lot like RDF (which we were finishing at the time). This may have been after Microsoft left the working group, but I cannot remember anymore.

Posted by ora at 07:02

2005-06-11

Two Towers

Some very disturbing developments have emerged in the Semantic Web community. Among the ongoing discussion on rules are proposals that will split the Semantic Web, as far as semantics goes. Newly seen versions of the "layer cake" suggest new approaches to how we are going to structure the technologies for the Semantic Web. This one (from Tim Berners-Lee's recent keynote talk) is particularly interesting:

New Semantic Web Stack

A recent paper from Horrocks et al is an excellent review of the current situation. Given that many existing rule languages (and proposals for rule languages) have Datalog semantics, we end up with the following situation (per my reading & understanding of things):

  1. Datalog cannot be layered on DLP, unless you adopt different semantics for DLP (for the purposes of this story, let's call that DLP-Datalog)

  2. DLP-Datalog cannot be layered on RDFS

  3. OWL cannot be layered on DLP-Datalog

  4. DLP-Datalog is not compatible with RDF semantics

From all this we have to conclude that it makes more sense to layer all this new stuff on top of XML (or some other syntax) and forget about RDF and OWL (at least as far as their semantics go - funny, I always felt semantics was the important part; Semantic Web and all that, you know). Does this all sound scary? You betcha!

In a way, the Semantic Web community is in a danger of splitting into a camp that makes the Closed World Assumption (and the Unique Name Assumption) and to another one that doesn't. So far I haven't seen any unifying "logical framework" that some people have been suggesting. And despite the fact that we originally started building RDF with, say, OO models and databases in mind, I firmly believe that the Web needs the "Open World" Assumption (even if building systems that make that assumption may be harder).

Of course, apart from the Semantic Web (or KR community), the other significant stakeholder of possible future W3C work on rules is the "business rules" community. There, rules are more like a programming paradigm rather than KR, and my take on this is that it may be foolish (or at least quite optimistic) to assume that both communities could be satisfied with the future outcome of such an activity. I may be wrong, but I am assuming that in the business rules community there's nothing wrong with the Closed World Assumption (in fact when dealing with databases it is sort of the natural and desirable way to go).

All this makes me worried. Fortunately, the recent W3C workshop on rules did note in their report that

"The workshop gave many indications that a W3C Recommendation here would be useful, but it was less clear what sort of standard would satisfy a sufficient base of users. In any Activity Proposal following from this workshop, a Working Group should be given a clear and narrow scope, making it easy to determine its relevance to various parts of the greater rules community."

But still, I fear that not all people see the gravity of the emerging situation. My "conspiracy theory" is that (given the long-standing controversy surrounding RDF etc.) the opponents of the Semantic Web will now be able to claim that "see, you could do it with just XML", however stupid such a statement actually is.

And besides, I never liked Tolkien anyway...

Posted by ora at 06:54 | Comments (3)

2005-06-07

Getting closer to releasing Wilbur2

One of the reasons for moving from Wilbur to Wilbur2 is not only that I wanted to do a redesign of (some parts of) the system, but that I also wanted to "reorganize" the source code, and with CVS this seems so cumbersome. So I have decided that the old Wilbur will remain in the CVS where it is, and I will start a new module altogether (perhaps called "wilbur2" or something).

At the moment, I have a prototype Wilbur2 running, with source code arranged in directories approximately as follows:

src/
    wilbur.asd
    core/
        core-data.lisp
        data-sources.lisp
        http-client.lisp
        literal.lisp
        rdf-parser.lisp
        wilbur-package.lisp
        wilbur-ql.lisp
    nox/
        core-constants.lisp
        nox-package.lisp
        xml-parser.lisp
        xml-util.lisp
    goodies/
        daml-parser.lisp
        index-and-match.lisp
        ivanhoe.lisp
        processes.lisp
        rdf-inspector.lisp
schemata/
    wilbur.rdf

I separated "nox" into a directory of its own, mainly because it uses a separate package. The "goodies" directory contains stuff that (strictly speaking) is not needed for running Wilbur, but can be useful (also, some "legacy" stuff is there as well). I anticipate putting some contributed code there too. And yes, I have given up on trying to find the ultimate defsystem and decided to just go with ASDF.

The RDF schemata that comes with current Wilbur will be deprecated. Just load the stuff from where it is supposed to be loaded...

For those who are curious, "index-and-match.lisp" contains stuff that supports my RDF browser ("OINK", yet to be released), things like full-text indexing of literals, regexp matching, etc.

I also have a SQL-interface in the works, based on CL-SQL, but it will require more work to make into the first release of Wilbur2.

Posted by ora at 10:30 | Comments (8)

Apple switching to Intel processors

Well, I didn't believe it either (until now). I enjoyed this comment on Slashdot: "Man, it is cold in hell today. Brr."

Posted by ora at 10:18