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RE: network endpoints

From: Booth, David (HP Software - Boston) <dbooth@hp.com>
Date: Thu, 1 May 2008 02:22:09 +0000
To: Jonathan Rees <jar@creativecommons.org>
CC: "public-awwsw@w3.org" <public-awwsw@w3.org>
Message-ID: <184112FE564ADF4F8F9C3FA01AE50009FCF23118C9@G1W0486.americas.hpqcorp.net>

> From: Jonathan Rees [mailto:jar@creativecommons.org]
> [ . . . ]
> Check the newer diagram [2] and tell me if you like it any better.
> [ . . . ]
> [2] http://sw.neurocommons.org/2008/inforesource2.pdf

It looks more accurate than the previous diagram.  But I'm now noticing that it says an IR is a "function from time to information", whereas the F&T definition is that an IR is a function from time to representation *sets*.  The difference is that the time parameter only determines a *set* of possible representations.  Other inputs such as language and mime type preferences, cookies, path, etc., determine the actual representation that is selected.  One could try to lump this set of possible representations together and say that they are all manifestations of the same abstract information, and that *is* reasonable for the portions of the input that pertain to content negotiation.  But the input that selects the representation is broader than only being for content negotiation, and differences can cause arbitrarily different representations to be selected.  The set of potential representations could be infinite.  This is why I said that the F&T function is essentially a curried function: when the time parameter is fixed, you still in essence have a function from request input to representations:

        fRoy: Time --> (Request --> Representation)

or equivalently, since a function is basically just a set of pairs:

        fRoy: Time --> (Request x Representation)

However, fRoy does not *exactly* match the F&T definition, because for a time t, fRoy(t) is a set of <Request,Representation> *pairs*, rather than being a set of <Representation> singletons.  This seems to mean either that F&T have glossed over how an appropriate member of this set of singleton Representations is selected , or it means that their notion of "representation" actually corresponds to what I have called a <Request,Representation> pair.  In either case I think this glitch is relatively minor: the correspondence between the F&T definition and the ftrr:IR definition of "information resource" given in
is quite strong.

David Booth, Ph.D.
HP Software
+1 617 629 8881 office  |  dbooth@hp.com

Opinions expressed herein are those of the author and do not represent the official views of HP unless explicitly stated otherwise.
Received on Thursday, 1 May 2008 02:24:07 UTC

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