Issue 6498: ptc-03-09-15/Explain the new association modeling constructs (uml2-rtf) Source: David Frankel Consulting (Mr. David Frankel, david(at)dfrankelconsulting.com) Nature: Uncategorized Issue Severity: Summary: Issue: The Core’s abstract syntax makes heavy use of new association modeling constructs. Two of them in particular may be unfamiliar to many who read the submission: · Subsets · Derived unions The submission provides only a brief explanation of these two new constructs, which I quote below: "A navigable property may be marked as a subset of another, as long as the owner of the subsetting property is the same as or a specialization of the owner of the subsetted property. In this case, the collection associated with an instance of the subsetting property must be included in (or the same as) the collection associated with the corresponding instance of the subsetted property. A property may be marked as being a derived union. This means that the collection of values denoted by the property in some context is derived by being the strict union of all of the values denoted, in the same context, by properties defined to subset it. If the property has a multiplicity upper bound of 1, then this means that the values of all the subsets must be null or the same." Recommendation: Since these constructs are so heavily used to define the Core itself, it would be useful for the submission to provide some overall guidance on how to use them. Providing rationale for why specific ones are chosen in specific places in the definition of the Core would be an effective way of disseminating understanding of these constructs and understanding of the Core as well. Resolution: Revised Text: Actions taken: November 7, 2003: received issue February 18, 2005: moved from infrastructure Discussion: Disposition: Deferred to UML 2.4 RTF End of Annotations:===== m: "David S. Frankel" To: Subject: UML2Infra-MOF2Core/ptc-03-09-15/Explain the new association modeling constructs Date: Fri, 7 Nov 2003 22:03:52 -0800 X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) Importance: Normal Issue: The Core’s abstract syntax makes heavy use of new association modeling constructs. Two of them in particular may be unfamiliar to many who read the submission: · Subsets · Derived unions The submission provides only a brief explanation of these two new constructs, which I quote below: "A navigable property may be marked as a subset of another, as long as the owner of the subsetting property is the same as or a specialization of the owner of the subsetted property. In this case, the collection associated with an instance of the subsetting property must be included in (or the same as) the collection associated with the corresponding instance of the subsetted property. A property may be marked as being a derived union. This means that the collection of values denoted by the property in some context is derived by being the strict union of all of the values denoted, in the same context, by properties defined to subset it. If the property has a multiplicity upper bound of 1, then this means that the values of all the subsets must be null or the same." Recommendation: Since these constructs are so heavily used to define the Core itself, it would be useful for the submission to provide some overall guidance on how to use them. Providing rationale for why specific ones are chosen in specific places in the definition of the Core would be an effective way of disseminating understanding of these constructs and understanding of the Core as well. ================================================================= David S. Frankel David Frankel Consulting Email: df@DavidFrankelConsulting.com Web: www.DavidFrankelConsulting.com Tel: +1 530 893-1100 Fax: +1 530 893-1153 David Frankel's MDA book: www.DavidFrankelConsulting.com/book.htm =================================================================