Nov 16 2007
Fragmentation Reprise
I got some good responses to my recent post that poked holes in the semantic web architecture. In comments, Peter Murray asked:
Is the nub of the nub of the problem that the client may not know what kind of representation it might get back when dereferencing a URI? If the client does know the type of representation, or if asking for a particular type of representation results in an error from the server, then it can assume to know what the fragment identifiers mean. Right?
While that is true, it’s not relevant to this argument. The core of the problem is that hashed URIs are inherently ambiguous. Its meaning depends on how you access it, which is nuts. Its as though a word has different meanings depending on whether you read it in a book or have it read out to you.
Bill de hÓra points to a similar writeup he did a month or so back (which I should have remembered and linked to when I wrote mine!). It contains this classic de hÓra line:
You really don’t want your absolute naming system for a planet to be driven by an arbitrary feature of a markup format
Danny weighed in with a long post that darted onto the representation vs description issue about which I also have a bit to say… but in another post 
3 Responses to “Fragmentation Reprise”
Thank you for taking time to expand on your original remarks. The analogy of the spoken versus read word worked for me. Bill’s posting is also very helpful in getting a handle on what the issue is.
Yeah, nice analogy. Suggests hash URIs are actually pronouns…
[...] I mentioned a while back that I wanted to talk more about the descriptions vs representations issue. A recent message by tmbl provided the impetus to do so. In that message he says the following: Try thinking of it this way instead. You are going to serve some representation on the web, for this thing. Are those going to be (a) ABOUT the thing, or (b) the CONTENT of this thing denoted by the URI? If the former, you must use # or 303. If the later, you can serve the representations with 200 from that URI. You see, 200 means (basically) “Here comes the content of the document you asked for” and 303 means “Here is the URI of document ABOUT the thing you asked for. [...]