- From: Pat Hayes <phayes@ihmc.us>
- Date: Mon, 1 May 2006 13:41:15 -0500
- To: "Booth, David (HP Software - Boston)" <dbooth@hp.com>
- Cc: "Frank Manola" <fmanola@acm.org>, <public-swbp-wg@w3.org>
> > From: Pat Hayes [mailto:phayes@ihmc.us]: >> >Booth, David (HP Software - Boston) wrote: >> >>>From: Frank Manola: >> . . . >> >>>1. An "HTTP endpoint", which is a >> >>>computational process running on hardware, >> >>>which processes the GET request and emits http >> >>>codes and bit-strings. >> >> >> >>Yes. This is the "information resource", defined in an operational >> >>style. >> >> >> >>Side note: I actually used the term "logical >> >>HTTP endpoint", not just "HTTP endpoint", >> >>because an "information resource" is associated >> >>with an entire URL minus the fragment >> >>identifier, whereas a Web server is (normally?) >> >>associated with only the domain+server part >> >>(ignoring the path and query string parts). >> >>For example, given the URI >> >>http://example.org/foo?bar#fum , >> >>http://example.org/ , http://example.org/foo >> >>and http://example.og?bar may all correspond to >> >>different "information resources", even though >> >>they would be served by the same Web server >> >>associated with example.org. >> > . . . >> We are now distinguishing between an endpoint and >> an implementation of an endpoint?? This is >> getting out of hand. So the running code is an >> implementation of a logical endpoint which is the >> real information resource. > >Correct. > >> Presumably I could >> implement the same logical endpoint somewhere >> else on the network, right? (If not, where is the >> utility in distinguishing them?) Would its URI >> still identify it - the logical endpoint - at >> that other place on the network? Or would it in >> fact identify the implementation? Etc. .. > >Great question! Yes, the old URI would still identify it, and the new >URI would also identify it. The new URI would be a URI alias[10]. That is not quite what I had in mind. I meant the case where there was a single URI, identifying the single logical endpoint (since, I gather, this is what it identifies), but that this single logical endpoint was implemented in two different places on the network. These two places might have nothing whatever to do with one another, and have no connection between them, other than both being implementations of the same 'abstract' endpoint. I realize that this hardly makes sense in network terms, since each 'place' has its own URI, but that is exactly my point: this seems to be a reductio ad absurdum of the claim that the URI identifies an abstraction as opposed to a network 'location' (in some broad sense, admittedly, of 'location'.) > > . . . >> >Also, it seems to me this is very much bound up >> >with the distinction being made between >> >information resources and other resources. This >> >distinction, and the different server return >> >codes being associated with it, seem to create a >> >binary (yes/no) answer to the question, "does >> >the representation that has been returned convey >> >all of the essential characteristics of the >> >resource denoted by the URI you've dereferenced" >> >(in the opinion of the person setting up the >> >relationship between the URI and the >> >representation that gets returned). Clearly >> >there's not a whole lot of room for nuance here >> >(!), but there does seem to be at least some >> >kind of semantic relationship. >> >> Well, no, I think that this virtually rules out >> any kind of semantic relationship, since I know >> of no way to analyze 'represents' semantically >> which would provide for ALL the essential >> characteristics of the represented to be captured >> by the representation. (It depends, of course, on >> what one means by the weasel words, in this case >> "essential".) Certainly a description cannot do >> this, except in cases not of wide interest (in >> mathematics, for example, where notions like >> 'abelian group' are defined so that they can be >> fully characterized by finite descriptions; >> notice that they have to be Platonic ideals in > > order for this to be possible.) > >Hold on. It sounds like you are now talking about "resources" in >general, rather than only "information resources". I meant to be talking about the latter. My point was that a representation of something, in any useful semantic sense of 'representation' that I am familiar with, can never represent ALL the characteristics of the thing represented (unless it actually is that thing, and is acting as a representation of itself; but this kind of self-representation is widely considered to be a pathological or extreme case. Eco rules it out by definition, for example.) Now, apply this to WebArch definition of 'information resource', and one seems obliged to conclude that it is impossible to represent any information resource. Pat -- --------------------------------------------------------------------- IHMC (850)434 8903 or (650)494 3973 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32502 (850)291 0667 cell phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Received on Monday, 1 May 2006 18:41:33 UTC