- From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
- Date: Wed, 11 Jan 2012 11:56:19 +0000
- To: Jim McCusker <mccusj@rpi.edu>
- CC: public-prov-wg@w3.org
- Message-ID: <EMEW3|d239ec78c95b49076eee8d49f10cc382o0ABuL08L.Moreau|ecs.soton.ac.uk|4F0D78E3>
Hi Jim, Answers to your questions below. On 01/05/2012 09:42 PM, Jim McCusker wrote: > Having read some of the relevant documentation more closely, I've > realized that my previous reading of this email was wrong, but what I > see now simply raises new questions. Hopefully this will be clearer > than my last email: > OK, I am answering this email, and not the previous. > 1) What is the difference between an entity identifier and an entity > record identifier? We don't have a notion of 'entity record identifier' any more (we need to check this has been consistently removed from the text). The rationale for this is that group felt it would be an burden on asserters to name entity records (given that entities are already named). > 2) Are identifiers allowed to be used across accounts if they are URIs? I assume you mean entity identifiers. Not sure what you mean by across. Yes, these identifiers can be used anywhere. In provenance records and in applications (independently of provenance). > 3) If the answer to 2) is no, then how do we refer to entities that > exist outside of provenance accounts? > I am not following you. Can you give an example of what you are trying to get to? Luc > Jim > > On Wed, Dec 21, 2011 at 4:08 PM, Luc Moreau <L.Moreau@ecs.soton.ac.uk > <mailto:L.Moreau@ecs.soton.ac.uk>> wrote: > > Dear all, > > Paolo and I had a discussion about identifiers, and felt that some > of the terminology > we used was confusing. Hence we have made some changes, which we > summarize here. > > 1. The identifier that occurs in an entity record is > the identifier of an entity ... and not the identifier of the > record > > 2. An account allows for three things: > - associating asserter with assertions > - scoping some structural constraints (new section 7.2) > - scoping for the uniqueness of identifiers > > 3. Constraint: > http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#identifiable-record-in-account > requires that for a given entity identifier there is a most one > entity record containing this identifier. > > > > We believe that with the following: > - entity identifiers can be URIs with the usual semantic web > understanding > - entity identifiers do *not* double up as URI for entity records > - with the above constraint, given an account and an entity URI, > we can find an entity record for > this entity. > > We hope these changes will help resolve the debate on > identifiers/accounts. > No doubt that we will discuss that at the teleconference tomorrow. > > Luc > > > > On 06/12/11 15:47, Provenance Working Group Issue Tracker wrote: > > PROV-ISSUE-183 (prov-dm-identifiers): identifiers in prov-dm > [prov-dm] > > http://www.w3.org/2011/prov/track/issues/183 > > Raised by: Luc Moreau > On product: prov-dm > > > Hi, > > It think that it is now time to have a proper debate about > identifiers in prov-dm since comments are regularly expressed > about them. I have raised this issue about this topic so that > we can track the conversation properly. Our hope is to reach > consensus on this topic by the time of the third working draft. > > First, in the fpwd, there was a mention of "qualified > identifier" (appearing in a note see [1]). We have removed > this term from the second working draft. > > Second, the complementarity record now explicitly allows for > linking entity records across accounts. Its syntax allows for > two accounts to be named. > > Third, identifiers for entities in prov-dm have a dual role > [3]. An entity has got an id (typically given by an > application). An entity record --- i.e. what we say about an > entity in a provenance record --- also has an id. There is a > consensus that we shouldn't mint identifiers for provenance > records. Hence, the identifier of the entity record is defined > to be the same as the identifier of the entity. > > The consequence of this is that two entity records in > different accounts may have the same identifier: they may say > different things about the same entity. For example, the > document ex:doc was generated by latex in account1, while in > account 2, ex:doc is described to be the result of a survey of > a field by different authors. > > This explains why we needed the complementarity record to name > the accounts as well. This assumes that account names need to > be named uniquely (see [4]). > > So, entity records identifiers are scoped to accounts. Note, > I said entity *records*, not entities. Hence, we are not > breaking the semantic web approach: an entity is a resource > and is denoted by a URI, and this remains true in all > accounts. (I guess that from a semantic web perspective we are > not looking at a provenance record as resource, since we don't > have a global URI to name it.) Finally, we allow for accounts > to be nested hierarchically; this fits nicely with abstraction > in provenance records. Again, see [4]. > > Can you express your views about this approach, as currently > defined in the second draft of prov-dm? > > Thanks, > Luc > > [1] > http://www.w3.org/TR/2011/WD-prov-dm-20111018/#expression-identifier > [2] > http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#record-complement-of > [3] > http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#record-Entity > [4] > http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#record-Account > > > > > > > > > > -- > Jim McCusker > Programmer Analyst > Krauthammer Lab, Pathology Informatics > Yale School of Medicine > james.mccusker@yale.edu <mailto:james.mccusker@yale.edu> | (203) 785-6330 > http://krauthammerlab.med.yale.edu > > PhD Student > Tetherless World Constellation > Rensselaer Polytechnic Institute > mccusj@cs.rpi.edu <mailto:mccusj@cs.rpi.edu> > http://tw.rpi.edu -- Professor Luc Moreau Electronics and Computer Science tel: +44 23 8059 4487 University of Southampton fax: +44 23 8059 2865 Southampton SO17 1BJ email: l.moreau@ecs.soton.ac.uk United Kingdom http://www.ecs.soton.ac.uk/~lavm
Received on Wednesday, 11 January 2012 11:59:26 UTC