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Centre for Complex Cooperative Systems
Modelling - http://www.cems.uwe.ac.uk/amrc/seeds/Modelling.htm.
Paper That includes PSL and XML Information - http://www.cems.uwe.ac.uk/~phale/ISPECE2003.htm.
PMXML Information - http://www.cems.uwe.ac.uk/amrc/seeds/PeterHale/PMXML.htm.
STEPml Information - http://www.cems.uwe.ac.uk/amrc/seeds/PeterHale/STEPml.htm.
The basis for much useful work in standardising modelling of information is XML (eXtensible Mark-Up Language). The reason for using this language is that it provides a structured way to represent information that is independent of the way this information is displayed. It is also open standard not proprietary. This is why XML is increasingly being used for communication of data between computer systems, this is the basis for Web Services (W3C, 2002). W3C (World Wide Web Consortium) 'develops interoperable technologies (specifications, guidelines, software, and tools'. Web Services are a means of allowing application to application communication, and acceptance of XML as a W3C standard helps to ensure that many applications are enabled to communicate using XML.
In addition to the use of open standard ontology languages, a further layer of agreed semantics can be used for the domain of manufacturing modelling. The Process Specification Language (PSL) (http://www.mel.nist.gov/psl/ of the National Institute of Standards and Technology (NIST) http://www.nist.gov/ is appropriate for agreed representation of manufacturing process semantics. This makes PSL appropriate for this thesis as a means to ensure the storage of process models created by users with the User Driven Modelling approach, could be made interoperable at the level of semantics.
Uschold and Gruninger (2004, 62) examine STEP (STandard for the Exchange of Product model data) for interoperability of systems such as CAD, and process planning software; and Process Specification Language (PSL) for exchange of process/workflow/production planning, scheduling, and simulation information.
The Process Specification Language (PSL) defines a neutral representation for manufacturing processes. Process data is used throughout the life cycle of a product, from early indications of manufacturing processes flagged during design, through process planning, validation, production scheduling and control. In addition, the notion of process also underlies the entire manufacturing cycle, coordinating the workflow within engineering and manufacturing.
Information is available on the National Institute of Standards and Technology (NIST) - PSL page - http://www.mel.nist.gov/psl/. Aditional Information on the rationale is available at http://www.mel.nist.gov/psl/rationale.html.
Time dependant ordering of processes is essential, in addition to the ‘type-of’ relationships represented for other sub-ontologies for this research. In XML, order is represented by position within a file, but higher layer ontology representation languages such as RDF(S) and OWL can represent sequences explicitly, PSL adds an engineering specific way of representing the sequence/process flow.
A processing sequence can be represented in PSL. PSL adds a layer of engineering semantics for communication between process modelling tools. This was devised by the Manufacturing Systems Integration Division of NIST (National Institute of Standards and Technology) [NIST] http://www.mel.nist.gov/msid/. PSL Items are declared as classes and used as instances, as shown in the diagram that displays this using a stylesheet. Process Specification Language and the NIST project are covered in Ciocoiu et al (2000) Ontologies for Integrating Engineering Applications, they describe the use of PSL as a translator for communication between process planning and scheduler applications and their users. As Semantic Web languages were used and produced in this thesis it is important to find a Semantic Web representation for PSL. PSL and other controlled vocabularies/ontologies are investigated by McGuinness (2003).
Ciocoiu, M., Gruninger, M., Nau, D. S., 2000 - Ontologies for Integrating Engineering Applications - Journal of Computing and Information Science in Engineering 1(1) pp 12-22.
McGuinness D. L., 2003. Ontologies Come of Age. http://www-ksl.stanford.edu/people/dlm/papers/ontologies-come-of-age-mit-press-(with-citation).htm In: Dieter Fensel, Jim Hendler, Henry Lieberman, and Wolfgang Wahlster, ed. Spinning the Semantic Web: Bringing the World Wide Web to Its Full Potential. MIT Press, 2003.
Uschold M, Gruninger M, 2004, Ontologies and Semantics for Seamless Connectivity, - http://www.sigmod.org/sigmod/record/issues/0412/12.uschold-9.pdf - Boeing, Univerity of Maryland - Association for Computer Machinery - Special Interest Group on Management of Data - SIGMOD Record December 2004 Vol 33 Number 4.
PSL can use XML, RDF (Resource Description Framework), and its own semantics to add a layer of engineering meaning to these Semantic Web languages for communication between process modelling tools, and for use in defining ontologies - These PSL examples make use of these languages and technologies as recommended in this publication - http://www.mel.nist.gov/msidlibrary/doc/nistir6459.pdf#page=76 :-
1. Use RDF Schema to represent the objects used in a process.
2. Represent timepoints as sequentially ordered groups of elements, with each timepoint element having a unique identifier. If the XML application uses a Document Type Definition (DTD), the unique identifier should be represented using an ID attribute so that references to the timepoint can be made using IDREF.
3. For each activity, specify a unique identifier (with an ID attribute if using a DTD) and an activity name. If the activity contains subactivities, specify these within a container element. If the activity has no subactivities, specify the resources used with references to the appropriate class defined in the RDF Schema.
4. Specify occurrences of activities in sequential order with sub-activities enclosed inside parent activities. Each activity occurrence should have a beginning and ending time point and, if it cannot be decomposed into sub-activities, a list of RDF-defined resource instances it uses.
Source -
Schlenoff, C., Gruninger, M., Tissot, F., Valois, J., Lubell, J., Lee, J. The Process Specification Language (PSL) Overview and Version 1.0 Specification (1999) - NIST Internal Report (NISTIR) 6459, National Institute of Standards and Technology - Appendix C: Mapping PSL Concepts to the eXtensible Markup Language (XML) Representation - pages 76-79 - http://www.mel.nist.gov/msidlibrary/doc/nistir6459.pdf#page=76.
The figure below shows a section from an example PSL process sequence based on the NIST example representation, and rendered using an XSL (eXtensible Stylesheet Language) stylesheet.
This example is just to illustrate the standard, the example could be expanded to be a full ontology and allow visualisation, navigation, and interactivity.
The first step is to declare the resources :-
Figure 1. Section from PSL Process Taxonomy and sequence rendered with stylesheet - PSL Class Definition
Instances of this class can then be declared :-
Figure 2. PSL Instance Creation
Time points are then created to make it possible to create a sequence of activities :-
Figure 3. PSL Time Point Creation
After timepoints are created, activities are specified :-
Figure 4. PSL Activity Specifications
The Activities are then assigned occurrence times that allow each activity to be related in a sequence of sequences :-
Figure 5. Activity Occurrence Times
PSL Process Taxonomy using XML http://www.cems.uwe.ac.uk/~phale/XMLDemonstrators/psl.xml - XML Example.
These semantics languages can be part of a larger effort to provide a Data Grid of information and applications, which can be requested as required (Walker, 2003).
So examples of XML being used to solve problems of manufacturing process information representation have been examined. XML can be used as a way to manage workflow within and between organizations (Ferreira & Ferreira, 2001). XML provides the basis for creation of taxonomies and Ontologies.
Varieties of XML that allow for additional semantics such as standardised representation of inheritance relationships, attributes and sequences or lists of items were also investigated. RDF and DAML/OIL (DARPA Agent Markup Language/Ontology Inference Layer) are represented using XML and allow for this additional layer of semantics (Harmelen & Horrocks, 2002). These syntaxes allow us to explicitly represent relationships such as class/subclass, attributes, and sequences. These information representation languages were used to represent Product Data Structures and Process, Materials, and Tooling libraries. An example of a Process Sequence represented by the layered XML/RDF/RDF Schema standard and displayed using a stylesheet is shown in figure 6.
Figure 6. Representation of Engine Ring Manufacturing Sequence
The above example could be extended to additional layered representation of DAML+OIL and/or OWL.
Link to RDF expressed within XML syntax http://www.cems.uwe.ac.uk/~phale/XMLDemonstrators/rdfring.xml
(Ribiere & Charlton, 2002) have evaluated languages, tools, and techniques for creating ontologies.
Process Specification Language and the National Institute of Standards and Technology (NIST) project are covered in Ciocoiu et al (2000), they describe the use of PSL as a translator for communication between process planning and scheduler applications and their users.
Agostinho C, Delgado M, Steiger-Garcao, A Jardim-Goncalves R, 2006. Enabling interoperability of STEP Application Protocols at meta-data and knowledge level, International Journal of Technology Management Volume 36, Number 4 - Pages: 402 - 421.
Ciocoiu, M., Gruninger, M., Nau, D. S., 2000. Ontologies for Integrating Engineering Applications - Journal of Computing and Information Science in Engineering 1(1) pp 12-22.
Ferreira, D. & Ferreira, J. 2001. Designing Workflow-Enabled Business-to-Business Infrastructures. 7th International Conference on Concurrent Enterprising: 81-89
Harmelen F. V. & Horrocks I. 2002. Questions and answers on OIL: the Ontology Inference Layer for the semantic web, http://www.onntoknowledge.org/oil/oil-faq.html Manchester University & Amsterdam University
Jardim-Goncalves R, Figay N, Steiger-Garcao A,2006. Enabling Adoption of STEP Standards Through the Use of Popular Technologies, Leading the Web in Concurrent Engineering, 2006, Edited by Ghodous P, Dieng-Kuntz R, Loureiro G, ISSN 0922-6389.
Walker D. W. 2003. Emerging Distributed Computing Technologies, http://www.cs.cf.ac.uk/User/David.W.Walker, Cardiff University
Athena - European Integrated Project - http://www.athena-ip.org/index.php?option=content&task=view&id=44&Itemid=89 - ATHENA - Advanced Technologies for interoperability of Heterogeneous Enterprise Networks and their Applications - is an Integrated Project sponsored by the European Commission in support of the Strategic Objective 'Networked businesses and government'.
INTEROP Portal - http://www.interop-noe.org/ - Interoperability Research for Networked Enterprises Applications and Software.
National Institute of Standards and Technology (NIST) - Process Specification Language (PSL) - A Few PSL Basics....
NIST - Process Specification Language Publicaions.
OWL/SWRL representation methodology for EXPRESS-driven product information model Part I. Implementation methodology, Zhao, W. and Liu, J.K. 2008. Computers in Industry - Article in Press, Corrected Proof - Abstract - This paper presents an ontology-based approach to enable semantic interoperability and reasoning over the product information model. The web ontology language (OWL) and the semantic web rule language (SWRL) in the Semantic Web are employed to construct the product information model. The traditional modeling language called EXPRESS is discussed. The representation methodology for EXPRESS-driven product information model is then proposed. The key of the representation methodology is mapping from EXPRESS to OWL/SWRL. Some illustrated examples are presented. - Keywords - Product information model; OWL; SWRL; EXPRESS; Ontology representation.
PLT Scheme - http://www.plt-scheme.org/ - PLT Scheme is an umbrella name for a family of implementations of the Scheme programming language.
PSL Rational - http://www.mel.nist.gov/psl/rationale.html.
PSL-XML - http://ats.nist.gov/psl/xml/process-descriptions.html.
STEPtools ST-Developer Tools Reference - http://www.steptools.com/support/stdev_docs/devtools/devtools.html.
The essence of the process specification language - 1999 - Volume 16 , Issue 4 (December 1999) table of contents - modeling and simulation in manufacturing - Pages: 204 - 216 - Craig Schlenoff - Michael Gruninger - Mihai Ciocoiu - Jintae Lee.
The Process Specification Language (PSL) Overview and Version 1.0 Specification (1999) - Craig Schlenoff, Michael Gruninger, Florence Tissot, John Valois, Josh Lubell, Jintae Lee.
The XML Cover Pages - http://xml.coverpages.org/psl-xml.html - Process Specification Language (PSL) and XML - July 06, 2000.
Unified Process Specification Language: Requirements for Modeling Process (1996) - Craig Schlenoff, Amy Knutilla, Steven Ray.
Business Process Execution Language - http://xml.coverpages.org/ni2005-10-13-a.html - XML Cover Pages - IBM and SAP AG Release WS-BPEL Extension for Sub-Processes (BPEL-SPE) - October 13, 2005.
XML (eXtensible Markup Language) - http://www.cems.uwe.ac.uk/amrc/seeds/PeterHale/XML/XML.htm.
RDF - RDF information and examples.
SVG - SVG Information and Examples.
SEEDS Page - SEEDS Home Page
Software Engineering Research Group - http://www.cems.uwe.ac.uk/cccs/researchgroup.php?menu=off&group=serg - SERG's mission is to bridge the gap between software engineering research and its application to different disciplines.
Peter Home Page - Peter Hale Home Page
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