- From: Graham Klyne <Graham.Klyne@Baltimore.com>
- Date: Fri, 11 May 2001 16:24:48 +0100
- To: Brian McBride <bwm@hplb.hpl.hp.com>
- Cc: fmanola@mitre.org, w3c-rdfcore-wg@w3.org
I'm a little concerned about the direction of this talk of entities and resources. I thought the URI spec was fairly clear that: (a) a resource is a "conceptual mapping" (b) an entity is a "bag of bits" I took Brian's stab at a formalism as being a way to say that the "conceptual mapping" that is a resource can be represented as a function that returns an entity. So, to me, it seems completely wrong to say that a resource can *be* an entity, even when there is only one entity associated with a resource. (By "associated with", I mean that can be returned by the function representation of the resource.) #g At 11:07 AM 5/10/01 +0100, Brian McBride wrote: >Frank Manola wrote: > > > > As I said in an earlier message, I think we need to clarify what > > "entity" means in our discussions. In particular, we need to > > distinguish between the definition of "entity" in the HTTP spec (where > > it is some payload that can be returned) and the definition in Brian's > > model, where "Entities are things like web pages, numbers and trees in > > the park". > >Exactly right. I may be at fault here for overloading the term. > > > (If the Web develops to the point where accessing what's > > identified by a URI can return a tree, I hope I get adequate warning > > before doing it!) > >I understand there was at one time (1st Apr 19xx) an RFC including a >mime type for matter transfer. All I could find in a google search >was a reference to a Simple Matter Transfer Prototol. > > > > > > I take Brian's model as being something like this (although Brian is the > > ultimate source of wisdom for *his* model): > >You have expressed it very well. > >There are several such 'model theories' if that is the right term that >will work for us. I picked this one as it seemed to me most consistent >with M&S. However, I'm more concerned that we have agreed on one, than I >am about any particular one. > > > > > > Finally, even though you can imagine two resources being mapped to the > > same entity, if different people are doing the mappings, it isn't > > necessarily going to be easy to decide when two resources are really > > equivalent. > >That may well be true :(. The reason for introducing equivalence was not >so that we could mechanically decide that two resources are equivalent, but >so that our model could represent equivalence. > >There isn't anything particularly deep here, its just about what we call >things. Web principles state that we can't rely on there being one true >URI identifying a particular entity - e.g. tree in the park. Anyone is >free to define a URI to name this tree. So we have a choice: > > - Resources have more that one URI > - each URI identifies a different resource, but we have the notion > of equivalence classes of resources > >I felt that the latter is closer to M&S and RDF. > >Brian ------------------------------------------------------------ Graham Klyne Baltimore Technologies Strategic Research Content Security Group <Graham.Klyne@Baltimore.com> <http://www.mimesweeper.com> <http://www.baltimore.com> ------------------------------------------------------------
Received on Friday, 11 May 2001 13:33:46 UTC