All Presentation Material Copyright Eurostep Group AB ® On Reference Data Libraries for Product Life Cycle Support David Price 6th NASA-ESA Workshop on Product Data Exchange, April 2004

® All Presentation Material Copyright Eurostep Group AB Topics AP239 Product Life Cycle Support DEX architecture Implementing a DEX What is OWL? Future and conclusions

® All Presentation Material Copyright Eurostep Group AB What is AP239? Product Life Cycle Support (PLCS) is a modular STEP Application Protocol for complex assets (e.g. ship) –Configuration Management As-Designed, As-Realized, As-Maintained –Support Engineering Support Required (activities, tasks, resources) –Resource Management Spares, Who/what/when –Maintenance and Feedback Failures, Replacements, … The above is a vast over-simplification

® All Presentation Material Copyright Eurostep Group AB PLCS Approach Fundamentals In ISO, standardize flexible data model that can be tailored using Reference Data Data Exchange Sets (DEXs) –Create “usage guides” for subsets of AP239 –Create “standard” Reference Data as a basis for implementation –Standardization in OASIS is planned Allow organization-specific extension to the standard Reference Data for further tailoring

® All Presentation Material Copyright Eurostep Group AB The STEP Architecture Application Activity Model - What process do I want to support? Application Reference Model - What are the information requirements of the activity in industry terminology? Application Interpreted Model - How do I model the required information using STEP and EXPRESS? Assembly Components Components of a STEP Application Protocol Implementation Method - What implementation technology do I need? Design Build Test definition relationship assm_rel

® All Presentation Material Copyright Eurostep Group AB The Modular STEP Architecture Common Resource Schemas Activity Model Application Protocol ARM MT AIM ARM MT AIM ARM MT AIM ARM MT AIM Normative Reference to Application Module Application Modules Use individual entity types Use entire module MT = mapping table describes what AIM entity types are used to exchange what ARM concepts

® All Presentation Material Copyright Eurostep Group AB Reference Data PLCS Requirements The red specializations do not appear in the actual AP239 schema AP239 ISO Schema Instead, they appear in Reference Data Libraries How do AP239/RDL relate?

® All Presentation Material Copyright Eurostep Group AB DEX Architecture STEPmod is the STEP Modules Repository –AP239 PLCS ISO standard is specified here DEXlib is where DEXs are specified –DEXs group and tailor “Capabilities” –Capability defines subset of AP239 EXPRESS, reads from STEPmod and allows usage guidance to be added Capabilities are reusable between different DEXs –An XML Schema for data exchange is generated from each DEX –DEXlib is also where PLCS standard Reference Data is defined STEPmod and DEXlib are XML-based

® All Presentation Material Copyright Eurostep Group AB STEPMod

® All Presentation Material Copyright Eurostep Group AB DEXLib

® All Presentation Material Copyright Eurostep Group AB STEPmod -express schemas -text descriptions DEXlib -capability -dex -rdl selection Standard Reference Data Library allowed classification adds usage guidance to Creating the DEX DEX XML Schema ISO Standard EXPRESS to XML Schema mapping

® All Presentation Material Copyright Eurostep Group AB Creating the DEX STEPmod ISO The PLCS standard EXPRESS information model DEXlib Extract: model defns. model subset Library of DEXs A DEX: Subset of AP239 EXPRESS + XML Schema for contracting for software conformance usage guidance MOD RDL PLCS standard RDL Defines RDL applicability Create using Protégé Class hierarchy Extend through sub classes

® All Presentation Material Copyright Eurostep Group AB When Implementing a DEX Organizations will likely specify extensions to the Standard Reference Data –Extension is defined by declaring organization-specific Classes as subclasses of the standard Classes –So, there are likely two or more RD libraries used in a DEX data exchange 1.The standard RD library 2.The organization extensions library

® All Presentation Material Copyright Eurostep Group AB OASIS DEXs -Capability -DEX -RDL selection -XML Schema Standard Reference Data Library MoD Reference Data Extensions DEX-based XML data exchange file System A System B subClassOf classification translate to translate from allowed classification

® All Presentation Material Copyright Eurostep Group AB What to do about Reference Data? We were contracted by UK MoD to do a survey of candidates for Reference Data Goal –Determine the best approach for Reference Data when applied to PLCS DEX data exchange Scenario –MoD has a specific business process to automate using PLCS/DEX-based data exchange Technical Assumptions –Exchange based on AP239 EXPRESS->P28 XML –Enable inclusion and reference to RD –Standard RD is extended in implementing organization

® All Presentation Material Copyright Eurostep Group AB Requirements arising… Create and manage standard RD Define what RD is used for what schema element Enable local extension of standard RD –Local extensions come from elsewhere in industry or within local organization –Possible later integration of local into standard RD Support implementation of pre- and post- processors –RD may be embedded, exchanged or referenced Support implementation of business process/rules –e.g. select, export, transfer, verify, import, report

® All Presentation Material Copyright Eurostep Group AB Initial Analysis Nothing to offer –OASIS had nothing really supporting RD –OMG had nothing really supporting RD although UML Profile for OWL is in-process Real candidates – –PLib – –W3C OWL –DEXLib DTD

® All Presentation Material Copyright Eurostep Group AB Our Conclusion While any of the candidates could be made to work, for our set of requirements OWL made the most sense In fact, we’ve also concluded that a specific set of tools should be used –Stanford University Protégé with OWL plug-in –Open-source, platform independent (Java) –Pre-load with template containing RDL, schemas, etc.

® All Presentation Material Copyright Eurostep Group AB What is OWL? The World Wide Web Consortium (W3C) created the HTML and XML standards OWL is a next-generation language standardized in the W3C. –its purpose is to add “semantics” to the Web Therefore, it can be distributed and is Web-enabled and does not assume a single source for everything –In concept, it is very much like other data modelling languages (it calls models or schemas “ontologies”) class, subclass, property, property type, instance/individual –it supports added set theory and logic-based statements about the classes and individuals –it has more than one syntax, XML being one

® All Presentation Material Copyright Eurostep Group AB Classes and Property Restrictions Class and subclasses Properties of Class Property Restrictions

® All Presentation Material Copyright Eurostep Group AB OWL Instances/Individuals Instance of Class “Person” Property Values

® All Presentation Material Copyright Eurostep Group AB Why this approach? OWL satisfies RDL modeling requirements –Class, multiple inheritance, properties, datatypes, instances, reuse of models –When UML Profile for OWL ready > Graphical RDL OWL satisfies RDL IT requirements –XML syntax, Web enabled –Easy map from 15926, , etc. Other factors –OWL will win in the market Industry and academic support Open-source tools available –People outside of SC4 know OWL, not or PLib

® All Presentation Material Copyright Eurostep Group AB Standard Refdata as OWLClasses MoD Refdata Extensions as OWL Classes -added refdata classes -added refdata/express usage DEX-based XML data exchange file subClassOf classification AP239 Schema as OWL Classes subClassOf Details of RD Relationships

® All Presentation Material Copyright Eurostep Group AB Some Reference Data in OWL

® All Presentation Material Copyright Eurostep Group AB The EXPRESS/RD OWL Link

® All Presentation Material Copyright Eurostep Group AB More on “Why this approach?” For business process and rules, reasoners seem like they have potential use While PLCS DEX exchange isn’t “Semantic Web”, this lays the foundation for future PLCS Semantic Web applications Makes “STEP” RDL usable by non-STEP applications

® All Presentation Material Copyright Eurostep Group AB Use of RDL plus inference Class: FamilyCarType Prop: Service interval = Km Class: FastCarType Prop: Service interval = 6000 Km RDL Onboard Engine management system Maintenance Planning System If Km since last service > Service Interval then do service A FastCar A FamilyCar Onboard Engine management system 7000 Km since last service 9000 Km since last service Example of STEP, RDL and Inference Engines triggering processes

® All Presentation Material Copyright Eurostep Group AB Use of RDL plus inference On board engine management system on a car sends file to Maintenance Planning System File contains Type of Car and Kms since last service (mileage) Maintenance Planning System looks up type of car in RDL and gets Service Interval property Inference engine rule triggered on Service Interval property and mileage and schedules a service

® All Presentation Material Copyright Eurostep Group AB Why this toolset? Protégé meets OWL/RDL modeling requirements –Can reuse existing ontologies (e.g. Dublin Core for identification and versioning) –Can create classes, properties and instances –OWL plug-in supports import/export/database Open-source GUI, API, database backend, reasoners –Uses HP open-source Jena API –Can add STEP-specific RDL plug-in if that becomes necessary Widepsread use ( downloads)

® All Presentation Material Copyright Eurostep Group AB The Obvious Concerns Semantic Web is still research –Approach doesn’t depend on Semantic Web technology –Using OWL as a modeling framework, the way is a modeling framework OWL is not an ISO/SC4 standard –Absolutely true! However, even a researchy W3C standard like OWL is more widespread than EXPRESS Have I wasted all my investment in STEP? –Absolutely not. Without the prior work, we would not be in a position to quickly take advantage of OWL. –Taking advantage of RDL –We can translate OWL to EXPRESS or or …

® All Presentation Material Copyright Eurostep Group AB Conclusion The flexibility defined in the PLCS/DEX approach allows it to be used across a wide domain –However, that flexibility means PLCS/DEX implementation depends on Reference Data The W3C OWL language provides very good capabilities for defining, reusing, publishing and relating “models” and “reference data” –By being Web-enabled, RDLs can be linked and distributed –OWL also enables the future use of logic engines as part of PLCS/DEX implementations The use of XML for the exchange file and OWL for the RD puts PLCS/DEX squarely into the mainstream, both now and in the future