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On Tue, 15 Oct 2002, Simon Waters wrote:
I'm guessing Adrian might want the gory details, I'm just curious.
OK, whether he does or not, lets have some basics. I've just dug up a post that summarises the problems without being too techie (IMO). <blockquote cite="http://lists.w3.org/Archives/Public/www-tag/2002Jul/0232.html";>
Annotea, for example, is a live and shipping product of W3C which allows people to publish assertions about "the thirteenth character in the HTML representation",
Annotea is an experimental system that show up numerous problems in diving straight in with mismatched technologies such as RDF and HTTP. 1. Annotea uses something it calls XPointer, which it applies indiscriminately to to HTML and Tag-Soup, as well as to XML. Annotea's pointers are not well-defined. 2. Annotea makes no provision for content negotiation. So the subject of an annotation is ill-specified. 3. Annotea doesn't even try to deal with content change. There is no way of telling whether an annotation applies to the page[1] as-is or as-was at some unspecified time in the past. 4. In the event of a content change being detected (e.g. with HTTP Last-Modified, Etag, etc), there is no way to tell whether the change affects the validity of the annotation. I recently posted references to my discussion of these problems, but just to recap: http://lists.w3.org/Archives/Public/w3c-wai-er-ig/2002Jul/0017.html http://lists.w3.org/Archives/Public/w3c-wai-er-ig/2002Apr/0029.html </blockquote> The fundamental issue is the overloading of URI. RDF uses them as words, and explicitly *doesn't* dereference them. However, when RDF is used to describe web content - as in EARL and Annotea - you must dereference URLs in order to get at this content. Annotea has confused these two incompatible uses of URL. If anyone wants more detail, see the messages referenced. As far as EARL is concerned, this is an open issue: see http://cgi.w3.org/ETA/issues.php3/wai/ER/?issues_id=682 (wendy doesn't put it all that well IMO, but at least it's there). -- Nick Kew -- The Mailing List for the Devon & Cornwall LUG Mail majordomo@xxxxxxxxxxxx with "unsubscribe list" in the message body to unsubscribe.