STEP MANAGEMENT OVERVIEW STEP ARCHITECTURE Module 4 Estimated Viewing Time: 60 Minutes

Sponsored By The National Institute of Standards & Technology Developed Under Contract by: Product Data Integration Technologies, Inc. 100 W. Broadway, Suite 540 Long Beach, CA 90802

Topics for This Module Data Architecture  STEP’s underlying semantic “backbone” Representation Forms  The EXPRESS Modeling Language Document Architecture  The structure of the STEP Standards documents Application Protocols  An introduction the implementable portion of STEP

Design Principles behind STEP vIncorporate meaning of data into a data structure vProvide a formal and computer sensible data modeling language vUtilize a development process that allows subject area experts to focus on the meaning of the data to be exchanged vRetain independence of data (enterprise information) from implementation types (a single representation (or model) can be used across all types)

Data Architecture: Shareable and Extensible vThe conceptual data models represent a consensus view of the data semantics commonly used in product data subject areas and understood by a category of application systems vThe reuse of general ideas within different contexts is supported by levels of semantic abstraction (encapsulation) vThe models are integrated into a single, conceptual schema using a consistent data architecture vThe semantics are partitioned to permit extension and pruning (modular design)

Aircraft: B-2 Bomber, engine, radar system B-2 Bomber prototype design 1 As-Design definition, As-Maintained definition, Functional-design definition Shape, material property, design requirement, functional characteristics Geometric model, chemical composition, textual description, measurements, numbers` Product Formation (version) Formation (version) Life cycle definition Life cycle definition Properties Representation STEP Data Architecture Simple Example

shape dimensional representation, geometric representation Properties Representation Geometry length=3 mm width=4.5 mm high-performance aerodynamic shape reference to a document Parametric Descriptive Raster Image boundary rep, constructive solid geometry planar surfaces, free form surfaces curves and points Solid Surface Wireframe STEP Data Architecture Population Example

Printed_circuit_assembly building_element piping_component part_library definition part_library definition manufacturing_planning definition manufacturing_planning definition functional_design definition functional_design definition Product Formation (version) Formation (version) Life_cycle definition Life_cycle definition STEP Data Architecture Semantic Extensions Examples Semantic Extensions Examples

STEP DATA Architecture Product Formation (version) Formation (version) Life cycle definition Life cycle definition Surface Wireframe Solid Geometry Properties Shape Material Surface Finish Structural Behavioral Representation Raster Image Descriptive Parametric Examples of capabilities for the description of Properties and Representation

EXPRESS vDeclarative object-like, Pascal-like, information modeling language vUsed to specify data semantics and structure for Data Architecture and other STEP specifications vEntities, Types, Rules and Functions are basic constructs of EXPRESS vLogical collections of data constructs are partitioned into Schemas vFormal syntax permits automated processing of EXPRESS models

The EXPRESS Language SET [1:?] subcategories of product product_version version product_definition _relationship first_related _definition second_related _definition product_definition first_equivalent second_equivalent product_definition _equivalence product product_category Graphical Representation SCHEMA product_definition; TYPE identifier = STRING; END_TYPE; TYPE label = STRING; END_TYPE; ENTITY product_category; name: label; subcategories : OPTIONAL SET [1:?] OF product_category; of_product : product; END_ENTITY; ENTITY product_version; ident: identifier; name: label; description : OPTIONAL text; of_product : product; END_ENTITY; Textual Representation

STEP Document Architecture Application Protocols and Abstract Test Suites Parts 200+ & 300+ Generic Resources Parts Application Interpreted Constructs Parts 500+ Integrated Resources Application Resources Parts 101+ Implementation Methods Part 21 Physical File, Parts Data access method Description Methods Part 11 EXPRESS Framework Part 13 STEP Development Methodology Conformance Methods Part 31 Conformance Testing Methods: General Concepts Parts Reqs for Test Labs & Clients Test Methods for File & Data access method

Integrated Resource Parts vGeneral purpose product data specifications written in EXPRESS vProvide the "building blocks" or "vocabulary" for Application Protocols vTwo classes:  General Resources (40 series)  Application Resources (100 series)

Development of the Integrated Resources Generic Resources Shape Representation Structure Geometric Models Presentation Product Description Fundamentals Application Resources Finite Element Analysis Draughting

Application Protocols vAn Application Protocol defines the usage of STEP Product Data for a given application context. vAn Application Protocol represents a measurable and shareable subset of STEP capability that is expressed in an industry’s or discipline’s terminology.

Generic Resources Shape Representation Structure Geometric Models Presentation Product Description Fundamentals Application Resources Finite Element Analysis Draughting Application Protocol Concept Application Protocol Requirements Required STEP Resources Mapping

Generic Resources Shape Representation Structure Geometric Models Presentation Product Description Fundamentals Application Resources Finite Element Analysis Draughting Application Protocol #1 Requirements Application Protocol #2 Requirements Mappings Common Resources Application Protocols Share Common Resources

Application Protocols: Re-use and Specialize Common Constraints -- Example Assy_Structure (Network Structure) AssemblySchematic Schem_Diagram (Network Piping Piping_Run (Network Network Structure ShapeProduct Identifier Material Specification Version Integrated Resources

Elements of an Application Protocol vApplication Activity Model A function model that describes the activities and processes of defined application context domain. This is a requirement document. vApplication Reference Model An information model that describes the information requirements and constraints for an application context area. The model uses application-specific terminology and rules that are familiar to experts in the application area. vApplication Interpreted Model An information model that describes the STEP data structures required for functional equivalence with the application contexts' AAM's and ARM's. vConformance Classes Descriptions of the valid populations of the file, which serve to define conformant uses of the AP. AIM ARM AAM AP Test Purposes

STEP Exchange Format vPart 21: Clear text encoding of the exchange structure  Is the algorithm used in the exchange of data via a physical file format.  Result is a sequential file of ASCII characters described in a computer-interpretable form.  Defines the mapping from EXPRESS into the exchange file: ENTITY product_category; name: label; subcategories : OPTIONAL SET [1:?] OF product_category; of_product : OPTIONAL product; END_ENTITY; ENTITY product_version; ident: identifier; name: label; description : OPTIONAL text; of_product : product; END_ENTITY; #1=product_category(“process vessel”,(#2),$) #2=product_category(“tank”,$,#3) #3=product(“fuel storage tank, 55 gals”) #4=product_version(“ver-001”,”Original Design”,$,#3)

Standard Data Access Interface - SDAI vSpecifies a standard access mechanism to data- bases that can be specified in EXPRESS vPermits application system independence from data storage technologies vHas an object-oriented view of data, regardless of implementation vImplementations in a particular programming language require an interface language

STEP Conformance Testing Conformance Test Case (hardcopy) Validate IGES or Part 21 files Verdict Criteria Conformance Test Case (IGES or Part 21 files) Certification Validate Hardcopy Implementation Under test

STEP ARCHITECTURE End of Module 4