STEP - The Data Exchange Format A presentation by Mohan Krishna Nagamangalam on for Data Management for Engineering Applications 1

TROUVER LE NOMBRE MANQUANT? 2

FIND OUT THE MISSING NUMBER ? 3

OBSERVATIONS Description-Langauge. Resource-Mathematics. Protocol-Algebra. Implementation-Add,Sub,Average. (86+1),(88-1),(86+88)/2. Test Suite-Test cases Imposed by Algebra. (Eg: A natural number is always 1> its previous natural number) Conformance-Test of outcome. (86 +1=87) 4

CONTENTS Ice Breaking task. Motivation. Introduction. STEP Classes. Introductory Documents. Description Methods.(LANGUAGE) Integrated Resources.(MATHEMATICS) Application Protocols.(ALGEBRA) Implementation Methods.(ADD,SUB,AVG) Abstract Test Suites.(A natural number is always 1> its previous natural number) Conformance Methods and Testing.(86+1=87) Problems with STEP. Success Stories. Questions. Queries. 5

MOTIVATION Time-to-market a product should be as minimum as possible. Data Exchange Problem Transfer of data between different systems working on different domains.(Mostly common difference will arise in system functionality) Each software vendor uses their own proprietary data. Resolution Approaches Eliminate- By use of Single Vendor software. Translate- Develop Translation mechanisms for all. Exchange- By use of a common file format. 6

SOLUTION (TRANSLATE) TRANSLATORS: Vendor AVendor B Vendor DVendor C FIGURE 1: DATA EXCHANGE USING DIRECT TRANSLATORS 7

OPTIMAL SOLUTION (EXCHANGE) Vendor AVendor B Vendor D Vendor C FIGURE 2: DATA EXCHANGE USING NEUTRAL FILE FORMAT AND HALF-TRANSLATORS Neutral Format NEUTRAL FILE FORMAT AND HALF-TRANSLATORS: 8

COMPARISON No. of systems (n)No. of Direct Translators n!/(n-2)!No. of half translators (2n) Table 1: A Comparison of the number of translators required for direct translation and Translation using a neutral file format. 9

INTRODUCTION STEP (STandard for the Exchange of Product model data) is an international standard (ISO 10303) that provides an unambiguous, computer interpretable definition of the physical and functional characteristics of a product throughout its life cycle. Figure 3 : STEP in Product Life Cycle Stages FROM [4-Page 360] 10

STEP CLASSES/PARTS Application Protocols ( ) Application Intrepreted Constructs( ) Integrated Resources Generic(41-99) Aplication ( ) Introductory (1-9) Implementation Methods (21-29) Conformance Testing methodolgy and framework (31-39) Abstract Test suites ( ) Description Methods (11-19) Figure 4: STEP Classes 11

STEP CLASSES/PARTS Application Protocols ( ) Application Intrepreted Constructs( ) Integrated Resources Generic(41-99) Aplication ( ) Introductory (1-9) Imlementation Methods (21-29) Conformance Testing methodolgy and framework (31-39) Abstract Test suites ( ) Description Methods (11-19) Figure 5: STEP Classes (ordered according to coherent flow of my presentation) 12

INTRODUCTORY (1-9) Part 1 - Overview & Fundamental Principles. DESCRIPTION METHODS (11-19) These classes describe the languages and methods that are used to create a STEP file. Part 11 - The EXPRESS language reference manual. Part 12 - The EXPRESS-I language reference manual. 13

EXPRESS Textual conceptual schema language based on entity-attribute- relationship model. Has seven declarative constructs. – Schema,type,entity,constant,function,procedure and rule. – Seven pre-defined types used as the types of an explicit attribute in an entity declaration. Number,integer,real,string,logical,boolean and binary. Simple Examples: ENTITY point;ENTITY line X : REAL ;p0 : point ; Y : REAL ;p1 : point ; Z : REAL ;END_ENTITY ; END_ENTITY; 14

SCHEMA royal_family; TYPE date = ARRAY [1:3] OF INTEGER; END_TYPE; TYPE hair_type = ENUMERATION OF (fair,brown,black,red,grey,bald); END_TYPE; ENTITY person SUPERTYPE OF (ONEOF(male,female)); first_name: LIST [1:?] OF UNIQUE STRING; last_name : STRING; title: OPTIONAL STRING; birth_date: date; death_date: OPTIONAL date; children: SET [0:?] OF PERSON; hair: hair_type; DERIVE age: INTEGER:= years(birth_date); alive: BOOLEAN:= NOT EXISTS(death_date); INVERSE parents: SET [0:2] OF person FOR children; END_ENTITY; ENTITY female SUBTYPE OF (person) husband: OPTIONAL male; maiden_name: OPTIONAL STRING; WHERE w1: (EXISTS(maiden_name) and EXISTS(husband)) XOR NOT EXISTS(maiden_name); END_ENTITY; ENTITY male SUBTYPE OF (person); Wife: OPTIONAL female; END_ENTITY; RULE married FOR (female,male);(**to be written**) FUNCTION years(past : date) : INTEGER;(**to be written**) END_SCHEMA; FROM [1 Page 39] Code 1: Example of EXPRESS Schema 15

EXPRESS-G Express-G is a formal graphical notation of a subset of EXPRESS. It is defined in a normartive annex to PART 11 and is used for human communication. It provides constructs for the following: Attribute. Type. Schema and Inter-links. Entity and Entity generalization. Relationship and Cardinality. Multi-Page referencing. 16

EXPRESS-G notation Figure 6: EXPRESS-G notation of SCHEMA royal_family. FROM [1 Page 41] 17

EXPRESS-I EXPRESS-I is an instantiation language, which enables instances of a schema defined in EXPRESS. SCHEMA_DATA royal_family; George_VI = MALE { first_name->(´Albert´,´Frederick´,´Arthur´,´Geeorge´); last_name->´Windsor´; title->´One of the Kings of UK family.´; birth_date->(14, 12, 1895); death_date->(06, 02, 1952); hair_type->GREY; wife->?;}; Code 2:EXPRESS-I instantatition corresponding to above said EXPRESS schema FROM [1 Page 43] 18

INTEGRATED RESOURCES (41-49 and )  The conceptual building blocks for STEP. A/C to Example : Mathematics. GENERIC: Part 41 - Product Description and Support. …… Part 45 - Materials. …… Part 49 - Process Structure and Properties. APPLICATION: Part Draughting Resources. Part Ship Structures. …… Part Kinematics. Part Building Construction Core Model. 19

APPLICATION PROTOCOLS ( ) The STEP standard categorizes the various types of product data around Application Protocols (AP). Figure 7: Composition of an Application Protocol. Part Explicit Draughting. Part Associative Draughting. Part Configuration Controlled Design. Part Mechanical Design Using Boundary Representation. …… Part Electronic Printed Circuit Assembly, Design and Manufacturing. Part Electronics Test Diagnostics and Remanufacture. Part Electro-technical Plants AAM The pieces of product information that are needed for the activities. ARM A formal EXPRESS information model that captures everything. AIM A library of pre- existing definitions. CC State what a vendor needs to implement. 20

APPLICATION INTERPRETED CONSTRUCTS ( )  Overlap between two or more Application Protocols.  Shared constraints of the Integrated Resources.  Represent shared information between different applications. Part Edge-Based Wireframe. Part Shell-Based Wireframe. Part Geometrically Bounded 2D Wireframe. Part Draughting Annotation. ….. Part Faceted Boundary Representation. Part Elementary Boundary Representation. Part Advanced Boundary Representation. Part Constructive Solid Geometry. ….. 21

Implementation Methods (21-29)  Describe the correspondences between STEP and other formal languages. Part 21 - Clear Text Encoding of the Exchange Structure. Part 22 - Standard Data Access Interface. Part 23 - SDAI C++ Language Binding. Part 24 - SDAI C Language Binding. Part 25 - SDAI FORTRAN Language Binding. Part 26 - Interface Definition Language binding. 22

PHYSICAL FILE Part - 21  Consists of 2 sections. HEADER FILE_DESCRIPTION – description – implementation_level FILE_NAME – name – time_stamp – Author – Organization – preprocessor_version – originating_system – authorization FILE_SCHEMA – Schema_identifiers FILE_POPULATION SECTON_LANGUAGE SECTION_CONTEXT DATA Entity_occurences » Has a unique identifier, an instance of type specified in the protocol, of which the file as a whole is an instance. FROM [3] 23

Code 3: EXAMPLE IS ; HEADER; FILE_DESCRIPTION((‘British royal family details (incomplete)'), '1'); FILE_NAME(‘ROYAL.STEP', ' T23:38:00', ('Jon Oven'), ('The University of Leeds‘, 'England'). 'Hand-crafted systems. plc‘, 'Generic Almanack London. England‘, 'not approved for release'); FILE_SCHEMA(‘ROYAL_EXAMPLE‘)) ; ENDSEC; DATA; #1 = MALE {(´Albert´,´Frederick´,´Arthur´,´George´),/*first name*/ ´Windsor´,/*last name*/ ´One of the Kings of UK family.´,/*title*/ (14, 12, 1895),/*birth date*/ (06, 02, 1952),/*death date*/ #2,/*children*/.GREY., /*hair type*/ $ );/*wife (not included)*/ #2 = FEMALE (('Elizabeth‘, ‘Alexandra‘, 'Mary'), 'Windsor'. 'Elizabeth II’, ‘Defender of Faith', (21, 04, 1926), $,(#3, #6),.GREY., $ ); #3 = ……..… ; #6 =..#99.. ; #99 = ……...; #4 = ……..… ; ENDSEC; END-ISO ; FROM [1 Page 97] 24

ABSTRACT TEST SUITES ( )  Each AP there is a corresponding standard abstract test suite.  Provides the set of abstract test cases.  The data to be used for conformance testing of any implementation of the aplication protocol. Part ATS for 201. Part ATS for Part ATS for

Conformance Testing Methodology and Framework (31-39) Laboratory Tests which use the standard itself as a metric. Part 31 - General Concepts Part 32 - Requirements on testing laboratories and clients. Part 33 - Structure and use of Abstract Test Suites. Part 34 - Abstract Test Methods. Part 35 - Abstract Test Methods for SDAI Implementations. 26

SUCCESS STORIES McDonnell-Douglas Exchanged product structure information for the C17-Military freighter programme. Boeing Exchange engine information with its suppliers for the 777- Aircraft. Major re-bid of F-16 machined parts. STEP provided 95% reduction in printing and reproduction costs. 27

PROBLEMS WITH STEP Applications Protocols not integrated. Migration. Less awareness of overall architechture. Temptational use of Integrated Resources. 28

THANK YOU 29

What steps do you think, can be followed to uplift the lower side of STEP? 30

Applications Protocols not integrated. – Dedicated Work Package. – PDM Schema initiative of ProSTEP. Migration. – Software tools produced by ProSTEP (for VDA-FS and VDA-IS) and Japanese STEP center (for IGES). Less awareness of overall architechture. ON GOING STEPS. FROM [5 Page 5] 31

APPENDIX AAM-Application Activity Model. ARM-Application Reference Model. AIM-Application Interpreted Model. CC-Conformance Classes. IGES-Initial Graphic Exchange Specification. VDA-FS-Verband der Automobilindustrie – Flächenschnittstelle. VDA-IS-Vereinung der Automobilindustrie IGES Subset. 32

LITERATURE [1]Jon Owen : STEP – An Introduction ISBN : [2]Fundamentals of STEP [3] [4]Hirz Mario, Wilhelm Dietrich, Anton Gfrerrer, Johann Lang: Integrated Computer-Aided Design in Automotive Development. ISBN: , Springer [5]ProSTEP: Usage Guide for the STEP PDM Schema V1.2 Release 4.3,