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“Metadata DownUnder” Moving ISO & OGC standards into the Semantic Web Presented at “Metadata DownUnder” 11th Open Forum on Metadata Registries, Sydney,

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Presentation on theme: "“Metadata DownUnder” Moving ISO & OGC standards into the Semantic Web Presented at “Metadata DownUnder” 11th Open Forum on Metadata Registries, Sydney,"— Presentation transcript:

1 “Metadata DownUnder” Moving ISO & OGC standards into the Semantic Web Presented at “Metadata DownUnder” 11th Open Forum on Metadata Registries, Sydney, NSW, Australia Laurent Lefort 22 May 2008 Water For a Healthy Country

2 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Outline Ontologies and water data standards Transforming ISO TC 211 and OGC standards into ontologies Work on OWL versions for multiple standards Findings on the transformation methods Findings on the resulting ontologies and on how to build better ontologies What is the added value of Semantic Web technologies?

3 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Context: water resources management for Australia Water Resources Observation Network (WRON) program One of CSIRO’s Water for a Healthy Country Flagship themes Support to major research alliance between Bureau of Meteorology & CSIRO (WIRADA) to deliver mission-critical R&D Specific Activity on Water Data standards Hydrometric data Geospatial data Usage and entitlement data Models Source: Vertessy 2006: Australia’s water resources information imperative and the role of the Water Resources Observation Network (WRON)

4 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Interest in water data standards Water budget combining 4 sub-domains Atmospheric Water (& Climate) Surface water Groundwater (& Geology) Human use of water Need to manage features and observations Complex cross-domain interactions e.g. transfer between surface water and groundwater Need for a consistent standard basis (& method) Data and Metadata

5 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Generations of “standards” & integration complexity ASCII-based DB-based Registries XML Model-driven generation of XML schemas Custom XSL transfo. & web services Distributed systems with same db schema UML & XML schemas Reuseable XML schema stack Master Data Manag t OWL ontologies Semantic integration EPA STORET EPA WQX GWML WOML WFD schemas eWater (EU) SANDRE SANDRE XML Surface water & groundwater “standards” Integration support Standard users Standard developers ODM WaterML (CUAHSI)

6 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Semantic Web technologies for standards development RDF (Resource Description Format) for the “web of data”: annotations and links Value: flattened, web-compatible method to manage and link data into set of triples OWL (Web Ontology Language) for the web of (data) models Several variants based on description logic with different expressivity / scalability ratios Value: reasoning support to build class hierarchy and verify logical consistency

7 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Building expectation that OWL can be useful Past and present efforts to create and use OWL versions of standards Drexel University (HydroSeek) Uni of Muenster (ACE-GIS, SWING, EDINA) Discussions at the Water Resources Information Model Workshop (Canberra, Sep 2007) Recognition of the ontological value of some standards e.g. OGC Observations and Measurements Finney: Australian Marine Ontology, WALIS Forum 2008 Brodaric & Probst: DOLCE Rocks AAAI Spring Symp. 2008

8 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Reasons to share our experience in building ontologies High demand for OWL versions of standards Transition and ramping up period from a manual process to a semi-automated one Recently developed methods (ODM) and tools (TopBraid) to create ontologies from UML models or from XML schemas Re-evaluation of current standard development practice Push for harmonisation of spatial standards (INSPIRE) Development of OGC Model driven approach ISO Ontology group, led by Jean Brodeur Can SW help ISO TC 211? Can ISO TC 211 help SW?

9 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia What we present today Work on OWL versions for multiple standards ISO and OGC standards Standards based on ISO and OGC standards defined for the water domain Findings on the transformation method Comparison of ontology generation tools from UML models and from XML schemas Findings on the resulting ontologies Tactics to build better ontologies

10 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Standards to transform into OWL Focus on water standards describing Features & Observations because of our interest in: Reference datasets (continental scale) Identification of water features and of their topological and hydrological relationships Data exchange language for individual and aggregated observations

11 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Two key building blocks to build features and observations standards ISO 19109: Geographic information -- Rules for application schema Defines a method to specify features know as the General Feature Model (GFM) OGC Observations and Measurements (O&M) Refines the GFM method to manage observations Supported by common schema generation technologies (UML to XML schemas) To implement UML patterns out of “stereotypes” To create definitions on top of existing schemas Example of tools: ShapeChange, FullMoon (CSIRO)

12 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Common principles used for standards based on GFM and O&M A core model defines the main classes forming the standard Through their relation to other specified classes or to generic spatial definitions Extra design flexibility is given in three areas Attachment of properties to features, Introduction of externally managed code lists Provision for alternative usage (union) Specific restrictions on the applicability of the definitions can be added with a constraint language, such as Schematron

13 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Added value of the Observations & Measurements standard Two user-managed class hierarchies in GFM-based specs: Feature and FeaturesCollection: a Feature-type is characterized by a specific set of properties Up to five user-managed class hierarchies in O&M- based specs Observation, SamplingFeature, PropertyType, Procedure and Result An Observation is an Event whose result is an estimate of the value of some Property of the Feature-of-interest, obtained using a specified Procedure Stronger ontological value for O&M More branches and separation of concern: Example: Difference between Feature and SamplingFeature Feature for the real world objects e.g. an aquifer SamplingFeature to characterise how a measure is done e.g. along a borehole

14 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Standards transformed into OWL Application standards based on ISO TC 211 General Feature Model OGC Observations & Measurements Corresponding ISO/OGC standards from two origins: UML model grouping all the ISO TC 211 standards from the Harmonized Model Maintenance Group XML schemas from OGC (schemas.opengis,net) Including GML, SensorML, …

15 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Selected ontology generation methods XSL-based approaches XO (CSIRO-developed) from UML 2.0 or XML schemas to OWL Rhizomik.net xsd2owl.xsl (open source but restricted to non commercial usage) TopBraid Composer (commercial tool) Transformation from UML 2.0 and XML schemas to OWL Enterprise Architect files can be pre-processed with an EA-specific openArchitectureWare plugin

16 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Generated ontologies

17 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Example 1: om:Observation from XML schemas (TopBraid)

18 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Example 2: om:Observation from UML model (TopBraid) Long URIs based on package names hasFeatureOfInterest: [0..1]

19 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Example 3: om:Observation from UML model (XO)

20 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Example 4: om:Observation from XSD (Rhizomik)

21 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Important findings XML schemas easier to transform than UML models As long as the transformation tool is capable to process tricky xsd:include and xsd:import cases Modularity schemes in place for UML or XML schemas are not necessarily directly applicable in OWL Suggested alternative is to simply use the XML namespace scheme to group together schemas sharing the same namespace into one or a limited number of modules The method to define URIs works better with XML schemas than with UML models XSL-based approaches better handle low quality (or incomplete) UML input Known problems with UML/XMI files

22 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia XML schemas easier to transform than UML models UML models High variability in the usage of stereotypes Risk of problem if the UML model is not fully validated or messy XML schemas Availability of validation tools even for multi-part schemas Less work to interpret the modelling intent Always available directly or after generation from UML Tighter management of successive versions Being able to generate the same output from both types of input for the same standard is critical to strengthen the transformation process

23 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Modules (files), namespaces (prefix) and URIs (IDs) in OWL Difference with XML: can not have same namespaces in different modules

24 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Method to define ontology modules OMG ODM recommendation to replicate UML package is inapplicable in our view Too many modules and the wrong ones TopBraid’s UML import operation creates 184 OWL files for the O&M model (which includes the ISO TC 211 standards) Recommendation For XML schemas, group together schemas sharing the same namespace into one or a limited number of modules Define a method producing the same results for UML models Record the source module or schema as an annotation property for traceability and/or round trip purposes

25 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Method to define URIs Using UML package names to create URIs is not recommended See example 2 Keeping the original XML schema namespace works well in practice Maybe two generation options are needed To create separate definitions for different versions of the same source To merge definitions from different versions of the same source

26 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Three central issues with the current OMG ODM specification Modules derivation from packages Impossible to apply in practice (too many modules) Naming conventions to disambiguate property names Can lead to an explosion of the number of properties often not required Does not discuss the union & substitution group patterns which are widely used in ISO/OGC standards

27 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Building better ontologies Assumption Ontologies can help standards amateurs to understand them without reading the documentation or learning how they have been created This discussion Tactics to capture the semantic essence of ISO/OGC & derived standards

28 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Tactic 1: Stick to the original definitions Rendition of ISO standards which mirrors the original UML model Drexel University team ISO and OGC ontologies in OWL-Protégé 2.1 ( ) ISO 19103, , 19115, OGC Spatial referencing by Coordinates and GML Success factor: traceability to the origin of definitions (often overlooked)

29 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Tactic 1: benefits of traceability Handle multiple definitions of Observations OM1_Observation: published OGC O&M spec. (part 1) version 1.0 OM: Draft version of O&M GML: gml:Observation

30 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Tactic 2: Modularise, Winnow, Align with Upper Ontology University of Muenster (and EU projects partners) ACE-GIS: OWL-Protégé 1.2 (2004), SERES: OWL-Protégé 2.2 (2005), SWING: WSML (2008) Spatial representation (19107), Location ( ), O&M (alignment with DOLCE and SWEET) Generally based on a costly manual process Match what the end user wants Weaker traceability to the sources of definitions

31 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Tactic 3: Try to do both Replace the manual process by a smarter transformation designed to normalise the ontology skeleton Define the right branches at the top Isolate unambiguous primitives (e.g. units) Use modules/namespace/URIs to position source- specific definitions against common ones Specific effort needed to Reduce the number of root classes Create deeper class & property hierarchies Handle ambiguous property definitions

32 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Example of normalised ontology skeleton Define the right branches at the top Isolate unambiguous primitives (e.g. units) Use modules/namespace/URIs to position source-specific definitions against common ones

33 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Conclusions Better ontology generation tactics can help to satisfy the demand for OWL versions of (groups of) standards Three priority areas have been identified Systematically develop parallel transformation chains from UML and XML schemas to enable cross-checking of outputs Develop more convenient and more robust modularity, namespace and URIs schemes Give feedback to ISO/OGC Policy group on the compatibility of their approach with OWL

34 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Inputs for ISO Ontology group Can SW help ISO TC 211 (and OGC)? Modelling and reasoning power of OWL Sub-properties in v. 1.0 and role composition in v. 2.0 Top level class hierarchy skeleton: normalised form of ontologies, alignment to upper ontologies Can ISO TC 211 (and OGC) help SW? Method to define a standard as a derived product of another one Transposable experience on how to extend or restrict a specification Use cases to inform SW work on ontologies and rules

35 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Acknowledgements Thanks to: Ross Ackland, WRON Theme Leader, CSIRO Simon Cox, Research scientist, CSIRO and OGC Amit Parashar, CSIRO and Australian W3C office And also to: TopQuadrant for TopBraid Composer Rhizomik.net for xsd2owl.xsl Rick Jelliffe et al: XSL pre-processing of XML schemas

36 CSIRO ICT Centre Laurent Lefort Senior Research Engineer (Ontologies) Phone: Web: wron.net.au Contact Us Phone: or Web: Thank you

37 Backup slides

38 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Standards GeoSciML (Geoscience Markup Language) GFM-based, first standard to partially leverage O&M GWML (Groundwater Markup Language), WOML (Water Observation Markup Language) Two preliminary efforts based on O&M to create groundwater and surface water standards: CSML (Climate sciences Modelling Language) Adapting & completing O&M for Met/Ocean data DHS-GDM (Department of Homeland Security Geospatial Data Model) Huge compilation of standards for homeland security applications

39 CSIRO Moving ISO TC 211 & OGC standards into the Semantic Web “Metadata DownUnder”: 11th Open Forum on Metadata Registries Sydney, NSW, Australia Summary of the 4 methods Transfo. method URI manag t Modules based on OWL variant Comments TopBraid XSD NamespaceNamespaces using specific conventions  DLBest result in g al TopBraid UML Package  too complex URIs Package  too many modules DLImport not always successful  Rhizomik XSD Unique EL+Adapted to handle multi-part schemas XO UML Unique EL+Stereotypes (esp. Unions) 


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