Introduction

ISO 10303 is an International Standard for the computer-interpretable representation and exchange of product data. The objective is to provide a neutral mechanism capable of describing product data throughout the life cycle of a product and independent from any particular system. The nature of this description makes it suitable not only for neutral file exchange, but also as a basis for implementing and sharing product databases and archiving.

10303-16 is a member of the description methods series. This document specifies a mapping of SysML XMI to the EXPRESS language.

The STEP APs Domain models and the STEP Core Model are information model layer components that are part of the STEP Extended Architecture. These components are developed using SysML. In the past STEP information models were developed using the EXPRESS language. For legacy reasons it is therefore required to provide an EXPRESS schema derived from the SysML domain model. It is mandatory that the transformation from the SysML model to the EXPRESS schema is defined by a reference standard and guarantee a repeatable process applicable to future application protocols developments.

The Object Management Group (OMG) has standardized the XML Metadata Interchange specification (XMI) that integrates the OMG Systems Modeling Language (SysML), the OMG Unified Modeling Language (UML), the OMG Meta-Object Facility (MOF) and the World Wide Web Consortium (W3C) Extensible Markup Language (XML) standards. SysML inherits the XMI interchange capability from UML. XMI is a mechanism for the interchange of metadata between UML-based modeling tools and MOF-based metadata repositories. OMG has also standardized an XMI compliant interchange format for the SysML thus specifying a lexical representation of SysML models based on a standardized metamodel of the SysML. That lexical representation includes, among other things, the ability to interchange data type information, class information (or entities), groupings of classes providing namespaces for the classes (or schemas), associations between classes and inheritance between classes (or subtypes).

ISO has standardized the EXPRESS language (ISO 10303‑11:2004). It is used to specify information requirements in ISO 10303.

10303-16 specifies a description method of the STEP Parts family, which defines the transformation of SysML constructs to the EXPRESS elements. Because the XMI standard specifies the XML representation of SysML metamodel constructs, standardizing the binding of SysML constructs into EXPRESS elements supports the representation of SysML models as EXPRESS schemas. SysML metamodel concepts that appear in SysML Block Diagrams are mapped into data specifications defined by EXPRESS schemas. This document does not map all SysML metamodel constructs to EXPRESS elements, because 10303 SysML models do not use all SysML metamodel constructs.

The EXPRESS schemas are derived from the domain model by applying the implementation bindings on the SysML XMI. The EXPRESS binding is realized with XSL transformations, which transforms the SysML model into an EXPRESS Schema. The specified binding is a one-way transformation from SysML information model represented in XMI into an EXPRESS schema. Due to this limitation 10303-16 does not define the transformation of arbitrary SysML models to EXPRESS.

Readers of 10303-16 require detailed knowledge of the EXPRESS language, and SysML.

The structure, conventions and concepts of the EXPRESS language are defined in ISO 10303‑11:2004.

The main component of this standard is:

— the specification of the transformation from SysML XMI to EXPRESS for each STEP element modelled in SysML.

PD ISO/TS 10303-16:2021

Industrial automation systems and integration. Product data representation and exchange - Description methods: SysML XMI to EXPRESS transformation

Current

Published:

31 Aug 2022