1. All Presentation Material Copyright Eurostep Group AB ® A Meta-model of EXPRESS in UML for MOF and UML to EXPRESS David Price April 2002

2. ® All Presentation Material Copyright Eurostep Group AB Purpose This model is not a standard, just an example An introduction to EXPRESS –Shows the major EXPRESS constructs Uses a style similar to that of the meta-model of UML Serves as sample model for UML/XMI to EXPRESS stylesheets (tested on ArgoUML XMI files) At some point, a model like this built in MOF would enable direct use of XMI by EXPRESS –Currently, EXPRESS must be translated into UML via the ISO 10303-25 EXPRESS to XMI Bindings standard that is out for ballot in ISO TC 184/SC4 Industrial Data

3. ® All Presentation Material Copyright Eurostep Group AB Schemas define a Namespace

4. ® All Presentation Material Copyright Eurostep Group AB Schemas can share declarations

5. ® All Presentation Material Copyright Eurostep Group AB Instances are of Entity Types

6. ® All Presentation Material Copyright Eurostep Group AB Entity and Attribute may be Specialized

7. ® All Presentation Material Copyright Eurostep Group AB Types are domains

8. ® All Presentation Material Copyright Eurostep Group AB Aggregate and Primitive Types

9. ® All Presentation Material Copyright Eurostep Group AB Rules and Constants

10. ® All Presentation Material Copyright Eurostep Group AB Algorithms and Expressions

11. ® All Presentation Material Copyright Eurostep Group AB Next Steps Testing –Convert this UML model to a MOF model MOF uses a subset of UML –I think this model only uses that subset but this needs to be confirmed Using MOF, a better analysis comparing UML and EXPRESS can be done Enables MOF repository access to EXPRESS schemas –MOF is a standard for access to models/schemas –There are implementations of this Using XMI four layer architecture, Entity Instances can be exchanged in a very late bound XML document Standardization in ISO? OMG? Develop two-way EXPRESS/UML mapping

12. ® All Presentation Material Copyright Eurostep Group AB A Bit on UML to EXPRESS Testing a mapping via XSLT –Not a standard yet, ISO 10303-25 only does EXPRESS to UML Small subset of UML is supported – mapping summary: –UML Class -> ENTITY –UML Abstract Class -> ABSTRACT SUPERTYPE no other SUPERTYPE constraint created –UML Generalization -> SUBTYPE OF, Multiple inheritance is supported –UML Attribute (single valued) -> explicit attribute –UML string and UML Class string -> STRING simple type –UML boolean and UML Class boolean -> BOOLEAN simple type –UML int and UML Class integer -> INTEGER simple type –UML Class real -> REAL simple type

13. ® All Presentation Material Copyright Eurostep Group AB A Bit on UML to EXPRESS(2) The mapping summary continued –UML Association between Classes -> explicit attribute in two cases 1 - one end name = association name > explicit attribute at end with no, or different name 2 - existence dependence -> explicit attribute at end with dependency (i.e. lower bound is 0) –Assoc End 1 lower bound zero and Assoc End 2 lower bound not zero means Class 1 depends on Class 2 SET is created for upper bound > 1 if multiplicity is 0..1 then OPTIONAL is included if both association end lower bounds are 0 nothing is created except as in 1 above –this is because cannot tell which entity should own the attribute if both association end lower bounds are not zero nothing is created except as in 1 above no inverses are created