- From: Ryan Golden <ryan.golden@oracle.com>
- Date: Mon, 25 Jul 2011 12:57:14 -0500
- To: public-prov-wg@w3.org
- Message-ID: <4E2DAE7A.3060401@oracle.com>
I don't have a huge problem with "pil:snapshot," "pil:perspective," or "pil:view" as opposed to "pil:entity." To me, most of the proposed conceptualizations on the BOB topic at this point are isomorphic (except for Jim's)--we're just debating on terminology. One thing I would point out, though. In a set of provenance assertions, the terms "snapshot," "perspective," and "view" may subtly imply an "IVP of" style relationship, which may not necessarily be the case. If I assert "View B is derived from View A," the natural language term "view" makes a subtle implication (to me at least) that View B and View A are different views /of the same thing/. This is not necessarily the case. For example, "view" would look a bit funny in this assertion, whereas entity would not: "Oxygen is derived from Air (by the process of distillation)." Nevertheless, I could be happy with any of these terms for now. --Ryan On 7/25/2011 11:39 AM, Paolo Missier wrote: > Khalid just managed to put "snapshot", "perspective" and "view" in the > same sentence. I see this as a good sign :-) > > So, having put in a good word earlier for a variation of "snapshot", I > would like to go back for a moment to "view", as intended in the > database sense. > > As we all know a view is indeed a perspective on the underlying > database, and it has two key characteristics: > - it projects out irrelevant attributes (out of a potentially > unbounded number of them, as in our case) > - if you materialize a view, this materialization remains valid only > as long as none of the attributes that it contains (those that matter > to the view) change their value in the underlying DB. When that > happens, you need to recompute the view (= create a new materialized > view, at least conceptually). > > Isn't that what BOBs do? > > In PIL the database itself is made of "things" (in Luc's latest > terminology as of today) that we can only talk about and partially > reveal by creating (mutiple) views, each valid within some temporal > window, which is defined by value change events in its attributes. > > this also avoid the "frozen in time" connotation that snapshots have > in several contexts. > > -Paolo > > On 7/25/11 11:07 AM, Khalid Belhajjame wrote: >> On 25/07/2011 10:24, Luc Moreau wrote: >>> The problem with Snapshot (like state, etc), is that it is the >>> snapshot of an entity. >>> We just don't want to distinguish an entity from its state, or an >>> entity from its snapshot. >> On the other hand, Snapshot has the advantage of conveying the fact that >> it is a description from a certain perspective (view). >> >> khalid >> >>> Hence, using Entity avoids this problem. >>> >>> Luc >>> >>> On 07/25/2011 10:19 AM, Paul Groth wrote: >>>> I thought we were getting somewhere with snapshot..... >>>> >>>> I don't think ENTITY really captures the intuition behind a BOB. It's >>>> too general. >>>> >>>> thanks, >>>> Paul >>>> >>>> Luc Moreau wrote: >>>>> The word 'Entity' should also be considered for the construct BOB. >>>>> >>>>> If we do so, the text 'characterized entity' should be replaced by >>>>> something else in the draft specification. >>>>> Why not 'thing'? >>>>> >>>>> >>>>> So, the text could become: >>>>> >>>>> Section 4. >>>>> In the world (whether real or not), there are things, which >>>>> can be >>>>> physical, digital, conceptual, or otherwise, and activities involving >>>>> things. >>>>> Words such as thing or activity should be understood with their >>>>> informal meaning. >>>>> This specification is concerned with characterized things, >>>>> that is, >>>>> things and their situation in the world, as perceived by the >>>>> asserter. >>>>> >>>>> Section 5.1 >>>>> An ENTITY represents an identifiable characterized thing. >>>>> >>>>> >>>>> Luc >>>>> >>>>> On 07/24/2011 11:43 PM, Reza B'Far wrote: >>>>>> First, for the record Khalid was the person suggesting Snapshot :) >>>>>> >>>>>> The way I've seen snapshot used commercially, it's fairly consistent >>>>>> with the current definition of BOB. There is some murkiness on both >>>>>> sides (how "snapshot" is used commercially and I think we're still >>>>>> iterating here on the definition of BOB, but may be that's close >>>>>> to be >>>>>> finalized). However, I think they are close enough. What I liked >>>>>> about "Snapshot" is that its intuitive and is used in several >>>>>> domains >>>>>> that I know of (content management, legal, configuration systems, >>>>>> and >>>>>> I've also seen use-cases in microfilm production by old-school >>>>>> librarians). Also, I think "Snapshot" offers a huge advantage that >>>>>> it's neither explicitly linked to the entity nor its state. And I >>>>>> know the distinction between entity vs. entity's state and how >>>>>> that's >>>>>> articulated has been in a lot of the discussions. Using "Snapshot" >>>>>> sort of obsoletes that discussion. >>>>>> >>>>>> On 7/24/11 12:57 PM, Stephan Zednik wrote: >>>>>>> I am not partial to snapshot, partially because of the extensive >>>>>>> functional usage of the term. I have always associated a snapshot >>>>>>> with a point in time, not a duration - but this may be an incorrect >>>>>>> association. >>>>>>> >>>>>>> I am open to discussing it, but my initial inclination was negative >>>>>>> towards it. >>>>>>> >>>>>>> Will we use the same definition as we have been using for BOB? >>>>>>> >>>>>>> --Stephan >>>>>>> >>>>>>> On Jul 24, 2011, at 9:52 AM, "Reza B'Far"<reza.bfar@oracle.com> >>>>>>> wrote: >>>>>>> >>>>>>>> I second the term "Snapshot". This term also has functional usage >>>>>>>> in several commercial application categories used within >>>>>>>> roughly the >>>>>>>> same meaning. >>>>>>>> >>>>>>>> On 7/24/11 3:45 AM, Khalid Belhajjame wrote: >>>>>>>>> Hi Stephan, >>>>>>>>> >>>>>>>>> Given the example you gave in your previous email, I think that >>>>>>>>> "EntitySpanshot" or "Snapshot" should be fine, given that it >>>>>>>>> reflect the fact that it is a description of an entity that holds >>>>>>>>> for some period of time. >>>>>>>>> >>>>>>>>> Do you agree? >>>>>>>>> >>>>>>>>> khalid >>>>>>>>> >>>>>>>>> On 23/07/2011 20:24, Stephan Zednik wrote: >>>>>>>>>> I do not feel that EntityInstance, EntityInstantiation, or >>>>>>>>>> InstantiatedEntity make sense for the book ownership >>>>>>>>>> scenario, or >>>>>>>>>> any scenario modeling the provenance of changes in >>>>>>>>>> characteristics >>>>>>>>>> of a physical object. >>>>>>>>>> >>>>>>>>>> To reiterate the example since I haven't committed it to a wiki >>>>>>>>>> page yet. Book X is an entity that represents a real world >>>>>>>>>> object. It can be put on a shelf, loaned to friends, damaged, >>>>>>>>>> and/or destroyed. It has important characteristics (condition, >>>>>>>>>> ownership, location, etc) that may change over the life of the >>>>>>>>>> book. We may want to represent the provenance of the book as a >>>>>>>>>> chain of ownership. >>>>>>>>>> >>>>>>>>>> |<----------------------------------------------------- Book X >>>>>>>>>> ----------------------------------------------------------------->| >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> |<!------ Book X with owner A ---->|<----Book X with owner B >>>>>>>>>> ---->|<---- Book X with owner A --------->| >>>>>>>>>> >>>>>>>>>> If a book changes ownership, is the "book with changed >>>>>>>>>> ownership" >>>>>>>>>> a different EntityInstance? A different InstantiatedEntity? I >>>>>>>>>> don't think what we current call a BOB is an 'instance of' >>>>>>>>>> anything. I think of it as a description of an entity that >>>>>>>>>> holds >>>>>>>>>> for some time period (not necessarily given) for which >>>>>>>>>> contextually important mutable characteristics of the the entity >>>>>>>>>> are held to be known. >>>>>>>>>> >>>>>>>>>> --Stephan >>>>>>>>>> >>>>>>>>>> On 7/22/2011 5:29 AM, Curt Tilmes wrote: >>>>>>>>>>> On 07/22/2011 03:43 AM, Khalid Belhajjame wrote: >>>>>>>>>>>> The term "Snapshot" was suggested some time ago, and it seems >>>>>>>>>>>> that >>>>>>>>>>>> several people did like it. >>>>>>>>>>>> We can also use the term "EntitySnapshot". >>>>>>>>>>> Following from snapshot: >>>>>>>>>>> >>>>>>>>>>> EntityInstance >>>>>>>>>>> EntityInstantiation >>>>>>>>>>> InstantiatedEntity >>>>>>>>>>> >>>>>>>>>>> Curt >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >> > >
Received on Monday, 25 July 2011 17:57:51 UTC