The ISO EXPRESS and Binary Data Project

Last Modified: June 2005

Following

ISO SC4 Valencia Meetings

Agenda

• Background

• Survey of the state of the art

• Requirements

• Making the standard

Background : Need

• STEP and related standard information models are written using the ISO EXPRESS language

• There are standard implementation methods for Text and XML exchange of EXPRESS-driven data– There are also low level standard Java, C and C++ programming

language interfaces for EXPRESS-driven data called SDAI

• Based on experience in the STEP for Space TAS/NRF, Finite Element Analysis, Computational Fluid Dynamics and other fields, requirements for a more efficient exchange format have arisen

Background : VIVACE

• Value Improvement through a Virtual Aeronautical Collaborative Enterprise– VIVACE EU project started January 2004 for four

years– EXPRESS-driven Large Volume Binary Data

Representation is defined as a VIVACE deliverable• Mats Lindeblad is VIVACE task leader from Volvo Aero• David Price is VIVACE technical resource from Eurostep

Limited• Mats and David are proposed as the ISO SC4 Project Leader

and Editor

Background : STEP Meetings

• Mats set up initial discussions at ISO STEP in Poitiers, France October 2003

• Team has met at each of the following ISO STEP meetings from 2004 onwards– Ft. Lauderdale : First announced meeting set out plan for Survey

of technologies and requirements gathering– Bath : Reviewed technologies and requirements, created

features analysis matrix– Seattle : Decided on HDF5 technology for first working draft and

testing– Lillehammer : Held workshop to produce proof-of-concept draft

specification– Valencia : Reviewed mapping and issues raised by initial coding

by HDF5 Group members

Survey of State of the Art

• Searched for binary data representations to find candidate technologies

• Search found– ASN.1 : Abstract Syntax Notation 1– HDF5 : Hierarchical Data Format– XML/Binary

• Sun Fast Web Services• WAP Binary XML• Compact Binary XML

– CGNS : CFD General Notation System– SDAI implementation by LKSoft

Gathered Requirements

• At each of the ISO STEP meetings, requirements were gathered– 40-50 requirements have been identified

• Based on requirements, a matrix of features was derived– Lists features needed by the proposed standard along

with a simple priority• Measured HDF5 against those features and

reviewed results in October 2004 at Seattle ISO STEP meeting– Based on this and knowledge of other candidates,

those present decided HDF5 was the most suitable

HDF5 Technology

• HDF5 is an open source API library

• HDF5 is more than simple compression, contained data has structure

“/” (root)

“/foo”

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Making the Standard

• The initial proof-of-concept draft published April 2005– based on a March 2005 workshop at the Lillehammer ISO STEP

meeting– Assume an ISO 10303-20s series part that specifies how to

represent EXPRESS-driven data using HDF5– After initial HDF5 investigation, it appears there is no immediate

need for SC4 to standardize an API– HDF5 includes an API and is studying possible standardization

in conjunction with ANSI

• A New Work Item ballot (NWI) is required by the ISO SC4 STEP procedures– The plan is to have significant implementation experience based

on a draft specification prior to submission as an ISO Technical Specification

NWI on “EXPRESS and Binary Data”

• Evident industry need for complement to ISO10303-21/28Usage Domains:– Engineering Analysis, Manufacturing, Measurements and more

• Represent EXPRESS-compatible data in an efficient, binary form• No standardized mapping from EXPRESS to binary exists• Support from participants representing:

– Sweden, UK, US, Japan, Germany, France known• Financing:

– Project Lead and Editor 2004-2007 from EU 6th FP project “VIVACE”• Mats Lindeblad• David Price

– PDES Inc, Engineering Analysis team agreed to prototype• Will propose NWI for project within SC4/WG11

– Proposed to target ISO 10303 Implementation Method– Planned Project Milestones => Next slide

WG11: EXPRESS and Binary Data

• Presentation and Discussion on Business Need for Standard• Review and Update of Gathered Requirements• Review of Potential Implementation Technologies from Survey

– Defined and prioritised an initial set of features for comparison• Planned Project Milestones:

– Jul 2005: NWI as SC4 Letter Ballot– Jul 2005 Release second Working Draft for review and testing– Sep 2005 HDF5 and Spec Training at PDES Inc Offsite (not yet

confirmed)– Oct 2005 (China SC4 meeting)

• Hold walk through for ISO/SC4 community– Mar 2006 (Naples SC4 meeting) walkthrough and implementation

reports and Release of CD document for ballot– Jun 2006 (France SC4 meeting) Hold CD ballot resolution work shop– Fall 2006 Final resolution workshop– End 2006: Publish ISO TS document

Training/workshop needs

• As no SC4-specific API is currently being developed, implementors will need to understand both– the HDF5 file structures and API– the ISO specification for representing EXPRESS-driven data

using HDF5

• A training session is being planned, expected for September 2005, where the NSCA HDF5 team can teach programming with HDF5 and the EXPRESS/Binary team can teach the standard

• Based on feedback from prototypes following the workshop, the ISO CD ballot specification can be completed

Major Mapping Considerations

• EXPRESS aggregations map to HDF5 Datasets containing an array so that HDF5 Partial I/O and other optimizations are possible

• The extend of each EXPRESS Entity Type is mapped to an HDF5 Dataset containing an Array for the same reason

• The HDF5 file can contain anything else it supports– e.g. a JPEG file can be included in the same file as EXPRESS-

driven data• For each EXPRESS Entity Type for which data appears

in the HDF5 file, a definitional set of information is included– The data in the HDF5 file references the definitional information

to define its type

Conclusion

• Sufficient industry interest and need exists for the EXPRESS/Binary data representation standard

• Good technology exists upon which to build a standard without inventing everything in ISO

• Anyone with similar needs/interests is invited to participate in the standard or in implementations