Issues for Mailing list of the EXPRESS Metamodel 1.1 Revision task Force

List of issues (green=resolved, yellow=pending Board vote, red=unresolved)

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Issue 13870: Question on InvertibleAttribute subclass of ExplicitAttribute
Issue 13905: Excess text in schema-interfaces-elements Definitions
Issue 18744: Correct CMOF file to MOF/XMI version 2.4
Issue 18745: Use UML PrimitiveTypes and not MOF: types
Issue 18746: Correct the OCL
Issue 18815: EXPRESS MM MOF model does not include the UML InstanceSpecifications in the specification

Issue 13870: Question on InvertibleAttribute subclass of ExplicitAttribute (express-rtf)

It seems an odd thing to me to create a subclass of ExplicitAttribute to 
instantiate for Attributes that have the potential to have inverses. I don't 
understand the rationale. Seems like it would be simper to have a constraint 
on InverseAttribute about it being owned by an EntityType referenced in an 
ExplicitAttribute

In clause 8.4.7.3, at the end of the Definition of AssociationEnd: interfaced-elements, delete the text ".interfaced-elements=.interfaces.refers-to" It is the derivation below.


In clause 8.4.18.1, at the end of the Definition of AssociationEnd: interfaced-elements, delete the text ".interfaced-elements=.interfaces.refers-to" It is the derivation below.


In clause 8.4.18.1, at the end of the Definition of AssociationEnd: referenced-in, delete the text ".referenced-in=.referenced-as.interfacing-schema" It is the derivation below.

I am puzzled by the use of the cmof: namespace in the cmof file.  At version 2.4.1 it is normal to use UML XMI files for metamodels – see, for example, the UML 2.4.1 metamodel itself (http://www.omg.org/spec/UML/20110701/UML.xmi).  I believe there is a fundamental misunderstanding here – from 2.4 onwards there is no longer any special cmof format.   I think that simply deleting all of the MagicDraw-specific content from 13-05-34 would give almost all of what you want; you would perhaps then need a mof:Tag for nsPrefix to make it a correct metamodel.

UML::Boolean (or PrimitiveTypes::Boolean) would be correct throughout the document (and MOF::Boolean strictly-speaking incorrect); and if the Express metamodel were to import the PrimitiveTypes model, then unadorned Boolean would do the trick nicely.

 

The OCL in the specification regularly uses the -> operator incorrectly.  The . operator applies to an individual and -> applies to a collection.  

The syntax of references to collections should also be checked.

 

 

The EXPRESS MM specification defines three Packages -- BuiltInTypes, BuiltInConstants, and GenericTypes – that contain UML InstanceSpecifications.  It also contains the Instance INDETERMINATE in the Instances package.  These InstanceSpecifications  represent predefined elements of the EXPRESS language that are instances of more general classes (of types and values) defined in the language.  Because MOF does not support InstanceSpecification, the v1.0 MOF model does not contain any representation of these model elements.  Standard representation of these model elements is critical to interoperable interchange of EXPRESS models.  Some MOF-compatible representation of these model elements must be included in the specification and/or the normative artifacts.