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PROV-ISSUE-183 (prov-dm-identifiers): identifiers in prov-dm [prov-dm]

From: Provenance Working Group Issue Tracker <sysbot+tracker@w3.org>
Date: Tue, 06 Dec 2011 15:47:37 +0000
To: public-prov-wg@w3.org
Message-Id: <E1RXxF3-00022A-UV@tibor.w3.org>

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
Received on Tuesday, 6 December 2011 15:47:43 GMT

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