RIM Issue: Association duplication and usage

[Len Gallagher <LGallagher@nist.gov>]

ebXML,

During last Friday's ebXML Regrep conference call, I agreed to raise a RIM
issue that we discussed but didn't have an immediate solution for. We
agreed it should be put on the Phase 2 Issues List.

In Section 10.1.1 (line 627-631, pages 28-29) RIM (version 0.60)
pre-defines the following Association Types:

  RelatedTo

  Packages

  ExternallyLinks and ExternallyIdentifies

  ContainedBy and Contains

  Extends

  Implements

  InstanceOf

  SupercededBy and Supercedes

  UsedBy and Uses

  ReplacedBy and Replaces

The issue is that, for the obvious pairs of association types, it is not
clear if one or both of the associations should become instances of the
Association class. The result is that a user is never sure which
associationType to query for when trying to find all instances of a given
source or target. Or if a user specifies one type of association for
insertion or deletion, does the implementation automatically enter or
delete the inverse instance.

One solution would be to define only 1-way associations so that a user
would know that the object being searched for is always a "Source" or a
"Target" of a given Association instance. This solution may or may not be
sufficient for the un-paired associations given above, e.g. RelatedTo.

Another issue to address at the same time is the privilege issue of who can
create new associations. A temporary solution is to require that both the
source and target objects of an association be owned by the Submitting
Organization, but that has obvious drawbacks. A better solution is to
specifiy ownership privilege rules so that others cannot insert new members
into a package you own, or others cannot submit a new object to replace an
object that you own, etc. 

Another issue to address at the same time is "specializations" among the
association types themselves. For example, is "Extends" a specialization of
"Uses"? Or, is there a specialization relationship between "Packages" and
"Contains"?


**************************************************************
Len Gallagher                             LGallagher@nist.gov
NIST                                      Work: 301-975-3251
Bldg 820  Room 562                        Home: 301-424-1928
Gaithersburg, MD 20899-8970 USA           Fax: 301-948-6213
**************************************************************