® Eurostep.ESUKPC20.000030v0.1©Copyright Eurostep Limited An Introduction to ISO STEP Part 25...

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Eurostep.ESUKPC20.000030v0.1©Copyright Eurostep Limited

An Introduction to ISO STEP Part 25

David Price

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Agenda

• Why Part 25?• EXPRESS/UML Mapping• Future

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Why Part 25?

• The ISO EXPRESS language has been used by the STEP, POSC, EDIF and other data modelling communities for 15 years

• Since the OMG standardized UML, it became a widely used software engineering language

• Part 25 is designed to allow software engineers using UML to reuse schemas modelled using EXPRESS

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How?

• Define mapping into OMG standards– OMG defined a subset of UML for use in defining

modeling languages• Meta-Object Facility or MOF

– OMG defined an XML encoding of anything modeled using MOF

• XML Metadata Interchange or XMI

– OMG defined a model of the UML language using MOF

• “UML Model Interchange” Model

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The Part 25 Vision

ModelInformation

ChangeEnvironment

ModelSoftware

GenerateSoftware

SCHEMA people;

ENTITY person;name : STRING;END_ENTITY;

ENTITY organization;name : STRING;members : SET OF person;END_ENTITY;

END_SCHEMA;

Start with an EXPRESSschema of the datarequirements ofthe domain of interest

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The Part 25 Vision

ModelInformation

ChangeEnvironment

ModelSoftware

GenerateSoftware

<XMI><UML:Class name=“Person”></UML:Class><UML:Class name=“Organization”></UML:Class></XMI>

Translate EXPRESS intoXML Metadata Interchangeformat (XMI)

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The Part 25 Vision

ModelInformation

ChangeEnvironment

ModelSoftware

GenerateSoftware

Use UML software engineeringtools to model the completesoftware system

Person Organization

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The Part 25 Vision

ModelInformation

ChangeEnvironment

ModelSoftware

GenerateSoftware

Generate much of theapplication in the programminglanguage of choice

public Person {}public Organization {}

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Conformance

EXPRESS text or XML parser

EXPRESS toUML metamodel

XMI syntax for UML metamodel

Specified inPart 11 or 28

Specified in Part 25

Specified in XMI

Part 25-basedEXPRESS toUML/XMI tool

EXPRESS schema

text or XML

EXPRESS language

DTD

XMI-compliant UML DTD

XMI encoding ofUML mapped

from EXPRESS schema

controlsif XML

controls

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Mapping Requirements

• The mapping was designed with “software engineering using UML” in mind– Round-trip, completely interoperable

EXPRESS/UML translation was not a requirement for Edition 1

– Consider UML an abstraction of Java, C++, etc.

• 80/20 rule and don’t “surprise” people who know both languages

• Part 25 defines a one-way mapping from EXPRESS 1 to UML 1.5– Based on the meta-model of UML, not the

diagrams

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Mapping Approach

• Mapping is viewed from a “context schema”, the top-level schema you want to implement– Schemas using other schemas are mapped

correctly– Anything not visible in context schema is ignored

• Map into native UML concepts on a “Static Class Diagram”– “vanilla” UML is the result– as round-trip not required, the fact that the UML

started life as EXPRESS is mostly lost

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Class Diagram Example

Association

Package

Class

Generalization

Attribute

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Mapping Issues

• UML Associations must be SETs– Only SET and LIST OF UNIQUE can map to

Association

• No built-in support for nested aggregation types

• What is a select type?• Default for UML Generalization is

disjoint/ONEOF, but is ANDOR/overlapping in EXPRESS

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Not Mapped

• RULE declarations• domain rules in ENTITY or TYPE declarations• UNIQUE rules in ENTITY declarations• SUPERTYPE declarations other than ABSTRACT

SUPERTYPE and complete ONEOF constraints• FUNCTION declarations• PROCEDURE declarations• CONSTANT declarations• explicit attributes redeclared as derived

attributes• remarks

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Mapping Schema, Entity, Type

Schema UML Package

USE FROM and REFERENCE FROM and AS

UML ElementImport and Alias

ENTITY and SUBTYPE OF and ABSTRACT SUPERTYPE and ONE OF

UML Class and Generalization and isAbstract and disjoint

TYPE x = SELECT UML Class and Aggregation Association named “selection_of”

TYPE x = ENUMERATION UML Enumeration and Enumeration Literals

TYPE x = not SELECT and not ENUMERATION

UML Class and Generalization with representation of underlying type being the parent

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Mapping Attributes

explicit attribute of simple data type and OPTIONAL

UML Attribute with corresponding type and Multiplicity set

explicit attribute of type ENTITY or TYPE reference and OPTIONAL and INVERSE

UML Association between Classes with Multiplicity set and reverse Multiplicity set as in INVERSE

explicit attribute of type SET or LIST OF UNIQUE ENTITY or TYPE

UML Association between Classes with multiplicity set as bounds

redeclared explicit attribute specializing domain to a subtype

OCL Constraint

explicit attribute of type other aggregation of ENTITY or TYPE

UML Multi-valued Attribute (UML Associations must be sets)

derived attribute UML derived Attribute or Association

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Mapping Aggregates and Datatypes

LIST or SET of simple type (referenced from TYPE or attribute)

UML Class named List-of-xxx or Set-of-xxx

nested aggregations UML Class named Set-of-Set-of-xxx and aggregation association named aggregation_of

STRING and INTEGER and BOOLEAN

UML String and Integer and Boolean

NUMBER and REAL Double equivalent to MOF/IDL, there is no native UML Double

BINARY Create new DataType called Binary, there is no native UML Binary

LOGICAL UML Enumeration and Enumeration Literals

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The Reverse• UML Package

– Schema• UML Class

– Entity Type– Select Type– Other Defined Type except Enumeration Type– Nested Aggregate Type (referenced from UML Attribute or

Association)– Simple Datatype (one option)

• UML Enumeration– Enumeration

• UML Association– single-valued explicit attribute : named type– SET or LIST OF UNIQUE : named type

• UML Attribute– all explicit attributes not mapped to UML Association

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EXPRESS (1)SCHEMA STEP_demo;

TYPE approval_assignment = SELECT ( Product, Product_version );END_TYPE;

ENTITY Product SUPERTYPE OF (ONEOF ( Requirement ) ); id : STRING; name : STRING; description : OPTIONAL STRING; versions : SET[1:?] OF Product_version;END_ENTITY;

ENTITY Requirement SUBTYPE OF ( Product );END_ENTITY;

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EXPRESS (2)ENTITY Product_version; id : STRING; name : STRING;END_ENTITY;

ENTITY Product_category; id : STRING; name : STRING; products : SET[0:?] OF Product;END_ENTITY;

END_SCHEMA;

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Example UML

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Nested aggregate EXPRESS

ENTITY our_entity;

our_matrix : ARRAY[1:3] OF ARRAY[1:3] OF REAL;

END_ENTITY;

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Nested Aggregate UML

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Use of OCLRedeclared explicit

attribute of_product in system_version

results in OCL Constraint with Name

and Body

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Redeclared explicit attribute

ENTITY system_version SUBTYPE OF ( product_version ); SELF\product_version.of_product : system;END_ENTITY;

Constraint Name redeclaredsystem_versionof_product

Constraint Body context system_version inv redeclaredsystem_versionof_product : self.of_product -> forAll ( oclIsTypeOf ( system ) )

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Future

• Edition 2 planning, ideas are:– Add support for EXPRESS 2 (highest priority)– Define EXPRESS using the OMG Meta-Object

Facility (now called UML Infrastructure or Core)• Result will be EXPRESS as one of the UML family of

languages or ability to use EXPRESS in some UML tools natively

– Support UML 2– UML Profile for EXPRESS

• Allow use of UML class diagram instead of EXPRESS-G• Supports UML to EXPRESS and perhaps round-trip

metadata interchange

– Further use of OCL in the mapping

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