STEP ARCHITECTURE Module 4 Estimated Viewing Time: 60 Minutes

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STEP ARCHITECTUREModule 4Estimated Viewing
Time 60 Minutes
STEP MANAGEMENT OVERVIEW
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• 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

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Topics for This Module

• Data Architecture
• STEPs 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

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Design Principles behind STEP

• Incorporate meaning of data into a data structure
• Provide a formal and computer sensible data
  modeling language
• Utilize a development process that allows subject
  area experts to focus on the meaning of the data
  to be exchanged
• Retain independence of data (enterprise
  information) from implementation types (a single
  representation (or model) can be used across all
  types)

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Data Architecture Shareable and Extensible

• The 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
• The reuse of general ideas within different
  contexts is supported by levels of semantic
  abstraction (encapsulation)
• The models are integrated into a single,
  conceptual schema using a consistent data
  architecture
• The semantics are partitioned to permit extension
  and pruning (modular design)

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STEP Data ArchitectureSimple Example
Aircraft B-2 Bomber, engine, radar system
Product
Formation (version)
B-2 Bomber prototype design 1
As-Design definition, As-Maintained definition,
Functional-design definition
Life cycle definition
Properties
Shape, material property, design requirement,
functional characteristics
Representation
Geometric model, chemical composition, textual
description, measurements, numbers
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STEP Data ArchitecturePopulation Example
Properties
shape
length3 mm width4.5 mm
Parametric
dimensional representation, geometric
representation
Representation
high-performance aerodynamic shape
Descriptive
Geometry
reference to a document
Raster Image
Surface
Wireframe
Solid
boundary rep, constructive solid geometry
planar surfaces, free form surfaces
curves and points
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STEP Data ArchitectureSemantic Extensions
Examples
Printed_circuit_assembly
Product
building_element
Semantic Extensions Examples
piping_component
Formation (version)
part_library definition
Life_cycle definition
functional_design definition
manufacturing_planning definition
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STEP DATA Architecture
Product
Examples of capabilities for the description of
Properties and Representation
Formation (version)
Life cycle definition
Shape
Material
Properties
Parametric
Surface Finish
Representation
Descriptive
Structural
Geometry
Behavioral
Raster Image
Surface
Wireframe
Solid
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EXPRESS

• Declarative object-like, Pascal-like, information
  modeling language
• Used to specify data semantics and structure for
  Data Architecture and other STEP specifications
• Entities, Types, Rules and Functions are basic
  constructs of EXPRESS
• Logical collections of data constructs are
  partitioned into Schemas
• Formal syntax permits automated processing of
  EXPRESS models

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The EXPRESS Language
of product
product
Graphical Representation
version
first_equivalent
of product
product_definition
second_equivalent
first_related _definition
second_related _definition
product_category
product_definition _equivalence
product_definition _relationship
SET 1?
subcategories

• 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
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STEPDocument Architecture
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Integrated Resource Parts

• General purpose product data specifications
  written in EXPRESS
• Provide the "building blocks" or "vocabulary" for
  Application Protocols
• Two classes
• General Resources (40 series)
• Application Resources (100 series)

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Development of the Integrated Resources
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Application Protocols

• An Application Protocol defines the usage of STEP
  Product Data for a given application context.
• An Application Protocol represents a measurable
  and shareable subset of STEP capability that is
  expressed in an industrys or disciplines
  terminology.

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Application Protocol Concept
Required STEP Resources
Application Protocol Requirements
Mapping
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Application Protocols ShareCommon Resources
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Application Protocols Re-use and Specialize
Common Constraints -- Example
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Integrated Resources
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Elements of an Application Protocol

• Application Activity Model
• A function model that describes the
  activities and processes of defined application
  context domain. This is a requirement document.
• Application 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.
• Application Interpreted Model
• An information model that describes the
  STEP data structures required for functional
  equivalence with the application contexts' AAM's
  and ARM's.
• Conformance Classes
• Descriptions of the valid populations of the
  file, which serve to define conformant uses of
  the AP.

AP Test Purposes
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STEP Exchange Format

• Part 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
1product_category(process vessel,(2),) 2pr
oduct_category(tank,,3) 3product(fuel
storage tank, 55 gals) 4product_version(ver-00
1,Original Design,,3)
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Standard Data Access Interface - SDAI

• Specifies a standard access mechanism to data-
  bases that can be specified in EXPRESS
• Permits application system independence from data
  storage technologies
• Has an object-oriented view of data, regardless
  of implementation
• Implementations in a particular programming
  language require an interface language

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STEP Conformance Testing
Conformance Test Case (hardcopy)
Validate Hardcopy
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STEP ARCHITECTUREEnd of Module 4