- From: Graham Klyne <GK@ninebynine.org>
- Date: Thu, 02 Jun 2011 20:45:59 +0100
- To: Khalid Belhajjame <Khalid.Belhajjame@cs.man.ac.uk>
- CC: Luc Moreau <L.Moreau@ecs.soton.ac.uk>, public-prov-wg@w3.org
Khalid Belhajjame wrote: > > Hi Graham, > > >I agree that many of the examples of derivation we have raised relate > to resource states. But if, as has been suggested by myself and others, > resource states are themselves resources >(especially when named for the > purposes of expressing a derivation), then such derivations can equally > be regarded as relating resources. I think that's more a difference of > terminology than >fundamental. > > Would it be fair then to say that in that view resources are immutable > resources? In the case of resources representing a snapshot of state, yes. > Which bring me to the question, do we want to express derivations > between mutable resources, or that is just something that we should > avoid at this point? (I'm finishing this email after today's telecon, so it's a bit of a re-run.) I think that many of our use-cases are based on invariant values, and the near-term goal is to find expression for these. So we definitely do want to express derivations between non-varying values. But in so doing, it's not clear to me (yet) that we need to exclude mutable resources, so I say let's keep our options open and not close off any possibilities that we don't have to. So my answer to avoiding mutable resources is: "yes and no". #g -- > > Thanks, khalid > >> >> Where I think I may diverge from what you say is that I would not >> limit such expressions of derivation to resources that happen to be a >> state (or snapshot of state) of some resource. I think defining that >> distinction in a hard-and-fast way, that also aligns with various >> intuitions we may have about derivation, may prove difficult to >> achieve (e.g. as I think is suggested by Jim Meyers in >> http://lists.w3.org/Archives/Public/public-prov-wg/2011Jun/0015.html >> (*)). >> >> #g >> -- >> >> (*) I just love the W3C mailing list archives - so easy to find links >> to messages, and thus capture provenance! >> >> Khalid Belhajjame wrote: >>> >>> Hi, >>> >>> From the discussion so far on derivation it seems that most people >>> tend to define derivation between resource states or resources state >>> representations, but not for resources. >>> >>> My take on this is that in a context where a resource is mutable, >>> derivations will mainly be used to associate resource states and >>> resource states representations. >>> >>> That said, based on derivations connecting resource states and >>> resources state representations, one can infer new derivations >>> between resources. For example, consider the resource r_1 and the >>> associated resource state r_1_s, and consider that r_1_s was used to >>> construct a new resource state r_2_s, actually the first state, of >>> the resource r2. We can state that r_2_s is derived from r_1_s, i.e., >>> r_1_s -> r_2_s. We can also state that the resource r_2 is derived >>> from the resource r_1, i.e., r_1 -> r_2 >>> >>> PS: I added a defintiion of derivation within this lines to the wiki: >>> http://www.w3.org/2011/prov/wiki/ConceptDerivation >>> >>> Thanks, khalid >>> >>> >>> >>> >>> On 01/06/2011 07:49, Luc Moreau wrote: >>>> Hi Graham, >>>> >>>> Isn't it that you used the duri scheme to name the two resource >>>> states that exist in >>>> this scenario? >>>> >>>> In your view of the web, is there a notion of stateful resource? >>>> Does it apply here? >>>> >>>> Thanks, >>>> Luc >>>> >>>> >>>> >>>> On 31/05/11 23:57, Graham Klyne wrote: >>>>> Luc Moreau wrote: >>>>>> Graham, >>>>>> >>>>>> In my example, I really mean for the two versions of the chart to >>>>>> be available at >>>>>> the same URI. (So, definitely, an uncool URI!) >>>>>> >>>>>> In that case, there is a *single* resource, but it is stateful. >>>>>> Hence, there >>>>>> are two *resource states*, one generated using (stats2), and the >>>>>> other using (stats3). >>>>> >>>>> Luc, >>>>> >>>>> I had interpreted your scenario as using a common URI as you explain. >>>>> >>>>> But there are still several resources here, but they are not all >>>>> exposed on the web or assigned URIs. I'm appealing here to >>>>> anything that *might* be identified as opposed to things that >>>>> actually are assigned URIs. (For example, the proposed duri: >>>>> scheme might be used - >>>>> http://tools.ietf.org/id/draft-masinter-dated-uri-07.html) >>>>> >>>>> (And the URI is perfectly "cool" if it is specifically intended to >>>>> denote a dynamic resource. A URI used to access the current >>>>> weather in London can be stable if properly managed.) >>>>> >>>>> (I think this is all entirely consistent with my earlier stated >>>>> positions.) >>>>> >>>>> #g >>>>> -- >>>>> >>>>>> Of course, if blogger had used cool uris, then, c2s2 and c2s3 >>>>>> would be different resources. >>>>>> >>>>>> Luc >>>>>> >>>>>> On 05/31/2011 02:25 PM, Graham Klyne wrote: >>>>>>> I see (at least) two resources associated with (c2): one >>>>>>> generated using (stats2), and other using (stats3). We might >>>>>>> call these (c2s2) and (c2s3). >>>>>> >>>> >>>> >>> >> >> > >
Received on Thursday, 2 June 2011 21:15:56 UTC