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2004-06-20
by earl, 3237 days ago
what i, personally, find most interesting regarding the recent weblogs.com outage are the migration strategies of the few weblogs.com sites i know of. LtU, definitely beeing the most notable among those sites, is switching to [create Drupal] and a new home at http://lambda-the-ultimate.org/.

if you try to netboot a soekris board connected to a zyxel P324 chances are high that zyxel locks up completely. more specifically if you use the zyx as dhcp server the soekris' dhcp requests cause the lockup. most likely there were reasons you bought a zyx, and yes there is of course a fix. namely the P324 3.61(JA.4)C0 firmware that was released on may 27, 2004. from the excellent release notes:

Modifications in V 3.61(JA.2)b1 | 10/27/2003
[..]
34. [BUG FIX] Symptom: Router will hang. Condition: 1. The DHCP client (a LAN PC) is a NT4.0 system. 2. When the DHCP client sends a DHCP request message, DHCP server (Router ) will hang forever.

the prompt bugfixing and perfect customer support are only a few reasons why i will stay with zyxel :)

Thomas Passin's book "Explorer's Guide to the Semantic Web" is readily available as Manning ebook. Some first impressions.

A first look at the RDF chapter (chapt. 2) is rather disappointing. The example to practically illustrate RDF, a "hypothetical database of references", is basically well chosen and the idea to illustrate an RDF realisation by comparing it to an E/R realisation is tenable, considering the widespread familarity with E/R ideas. However, the RDF realisation is, in multiple regards a rather bad example of how to model in RDF.

For example, the RDF realisation turns out to be a direct translation of the logical E/R model (as opposed to the conceptual model). The conceptual model has an n:m relation between "publication" and person", which is resolved via an "authorlist" entity in the logical model. Now this "authorlist" thing is carried over into the RDF model, resulting in a completely inappropriate solution. For the given scenario there is no reason to not simply use an "author" predicate to model this association, and even for more complex situations an "RDF-style" solution might look quite different.

Add to that the rather odd naming of things and the unlucky graphical presentation used in this very example and you may understand why I'm disappointed by the chapter.

Further, up to now I noticed 3 different notations for RDF graphs that are used in the book, namely a graphical one, RDF/XML and a custom text-based one utilizing curly brackets. N-Triples and N3 are mentioned very briefly. I don't really understand why it's necessary to use a custom notation instead of e.g. Turtle (or even N3). I think it would be rather advantageous to stick to something like Turtle/N3 which the reader will encounter in practice. At least the use of RDF/XML seems to be limited to one section explaining its basics.

That all put aside, skimming over the chapters on logic, ontologies and agents was promising. Interestingly enough, the example used in chapter 2 is picked up again in the ontology chapter, and now modelled in a "proper" RDF-style way. The OWL presentation is concise and well done, the examples are well chosen. I suspect the Topic Maps chapter will be fine as well, as the author is the creator of TM4Jscript.

Overall, mixed first impressions; but I remain in love with Manning's ebook programm :)
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