Transformation of EXPRESS Models Using OMG Technologies

1
Transformation of EXPRESS ModelsUsing OMG
Technologies

• Ed Barkmeyer
• Manufacturing Engineering Laboratory
• NIST

2
Outline

• What is EXPRESS?
• Approach to EXPRESS Migration
• The EXPRESS Metamodel
• Next steps

3
What is EXPRESS

• EXPRESS
• an information modeling language
• developed in the late 1980s
• standardized as ISO 10303-111994, revisions
  1999, 2004
• Used in manufacturing data exchange standards
• ISO 10303 (STEP) 200 data schemas
• ISO 13584 (PLIB) 50 data schemas
• ISO 15531 (MANDATE), 15926, 18876, etc.

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Features of EXPRESS

• Entity definitions
• somewhere between Class and Record
• attributes with data types, multiplicities
• inverse and derived attributes
• subtypes
• keys (UNIQUE rules)
• Type definitions
• basic types Integer, Real, Boolean, String, etc.
• aggregations ARRAY, BAG, LIST, SET
• (extensible) ENUMERATION
• SELECT (choice, union)

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Rules in EXPRESS

• Local rules
• allowable values for Types
• allowable values for attributes, inter-attribute
  relationships
• Global rules
• relationships of extents of entity types
• subtype relationships exclusion, covering,
  overlap, equivalence
• Rules defined by expressions
• Function definitions

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TC184/SC4 Approach

• Model-Driven Architecture vintage 1985
• data models, separate from implementation
• mappings to specific implementation languages
• common conceptual schema for product models
  developed area by area
• application-specific (i.e. usage-specific) views
• Enablers
• EXPRESS language ISO 10303-111994
• clear-text encoding ISO 10303-211994
• APIs mappings to C, CORBA IDL, Java
• XML encoding (2003), XMI encoding (2004)

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Reasons for Migration

• Much engineering knowledge captured in 200
  standard EXPRESS models
• Not accessible to most software experts
• EXPRESS is an uncommon language
• Not easily translated to new technologies
• platform-independent, platform-class
  dependentRelational database modeling style
• Need
• neutral form of knowledge
• formal translation languages

MOF
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Approach

• MOF metamodel of EXPRESS
• MOF QVT transform to UML v2 metamodel
• EXPRESS schemas to UML OCL models
• ISO 10303-25 v2, OMG RFC
• MOF QVT transform to Ontology Definition
  Metamodel
• EXPRESS schemas to OWL models
• EXPRESS rules modeled in ISO Common Logic
• OMG RFP or RFC
• Open Source implementations

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EXPRESS v2 Metamodel

• draft 24 May 2005

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Packages
Schemas
Language
Instances

Rules
Types
Algorithms
Expressions
Constants
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Meta-types for the EXPRESS Language
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Named Elements
13
Scopes
14
Naming
15
Schemas
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EXPRESS Types
DataType
ParameterType
(disjoint, total)
(disjoint, total)
InstantiableType
GeneralizedType
PartialEntityType
(disjoint, total)
(disjoint, total)
AnonymousType
EntityType
NamedType

isAbstract

Boolean

id

ScopedId
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Instantiable Types
18
Simple Types
19
Aggregation Types
20
Generalized Types
21
Entity Types
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Attributes
23
Type Scopes and Naming
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Algorithms
25
Rules
26
Constants
27
Expressions
28
Full Expression
29
Reference Expressions
30
Function calls
31
Initializer Expressions
32
Instances
33
Simple Values
34
Aggregate Values
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Entity Values
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Next Steps

• Verify/correct EXPRESS metamodel
• with ISO EXPRESS experts
• Develop mapping to ODM
• entities/types to OWL,
• rules to ISO Common Logic
• Develop mapping to UML v2 metamodel
• entities and types to class diagram elements
• rules to OCL elements

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Next Steps (continued)

• Build EXPRESS parser add-ons
• to produce XMI for EXPRESS metamodel
• Use MOF/QVT tools to implement mappings
• Propose ODM mappings to OMG
• OMG RFC? RFP?
• Propose UML mappings to ISO
• revision of ISO 10303-25
• OMG RFC after successful ISO ballot