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OGC Architecture gaps Architecture working group GeoSciML meeting Edinburgh 2011.

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Presentation on theme: "OGC Architecture gaps Architecture working group GeoSciML meeting Edinburgh 2011."— Presentation transcript:

1 OGC Architecture gaps Architecture working group GeoSciML meeting Edinburgh 2011

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3 W_S Components Vocab Feature Catalog Metadata WMS WFS SOS Model Ontology Mapping Expansion Reasoning

4 Archipelago of Fullmoon UML XSD RDFS Servicia HTTP bay Vocabularia Peninsula of SKOS SPARQL crossing Desert of OWL Ishme of mapping Bottomless Bay of metadata Catalog island WMS peninsula WFS jungle SOS swamps WMC harbour HMS GeoSciML III Island of portrayal Ocean of One Geology Sea of schematron Validation straight Capabilities straight 19115 Island HMCS GWML Soft-typing quicksands HMAS ERML REST reef Persistant URI range Ontology moat EBRim bay RIF bay broaderThan narrow Sea of nillables GML cliff O&M beach SWE hill OG Sea urgh

5 OGC Gaps with community schemas  How to provides vocabularies (vocab services and mapping)  How to document properties Complex value metadata Vocabulary  How to stitch services together into an application (WMS / WFS / **S)

6 Vocabularies  Delft meeting Discussion about Ontologies and vocabularies Mapping across vocabularies  USGS constrains. They have legal binding for using a specific vocab. OWL over SKOS (because OWL allows reasoning) Creating a WG ?

7 How to expose semantic info  Schema (service registry)  Domain of values  Mappings  Governance: responsibilities  Need one standard way of exposing semantic info Slides from Delft HDWG meeting

8 Action Items - 1  Harmonization report? Here are a few interesting efforts: BODC (British Oceanic Data Center ?) has done review of options for vocab services – extend it French geol survey with INSPIRE Bureau Of Meteorology : WaterML and Geosciences vocab services Model registry (Rob) Linked Open Data (they have really interesting stuff) Mediator in GWIE (à la GEON) CUAHSI ontology work --------------- Figure out common patterns and gaps Get OGC mandate to do it (geosemanticsWG?) Slides from Delft HDWG meeting

9 Action Items - 2  Report it as a current problem with OGC architecture  NGA interested? Cross-domain; water security; situation awareness JeremyT  Would OGC be interested in finding sponsors for an effort to fill this gap in architecture  White paper: Use cases; common issues; common gaps  Get on IE agendas Slides from Delft HDWG meeting

10 Property Binding  Goals Initiated from GWIE It’s beyond « GeoSciML » The XSD and Schematron rule are good to check after the fact but we can’t deduce all the « possible values » to create GUI Vocab informations are externalised and we need a way to « bind » this property to that vocabulary.

11 Property binding Use Case  Client application is provided a WxS URL, which is used to extract the service GetCapabilities.  The client application parses the capability files and depending of the service type, spawns a user interface  Client application provides the user with a list of queryable feature types  Users picks a feature type  Client application invokes "DescribeFeatureType" to the service and extract a schema  Client application then shows an interface where the user can build a filter, The user is provided with a GUI where at some point he can build a reference to a property The user builds a property path by progressively navigating the model Once the user reachs a literal property, it allows the user to enter a value  If the value must come from a vocabulary, the client application provided a way to browse through the list of possible terms.  If the value is schema constrained (with a pattern), the application can provide either post-entry validation, or more advanced components (such as a calendar tool)  Once the filter is completed, the client application can use the filter to interact with the service.

12 Issues with community schemas  How do we access a complete schema? If the feature has subtypes in another schemas, how can I be sure to know about them.  How do we bind a vocabulary to a property?  How do we store this binding  How do we parse the vocabulary (how can we know the format)  What literal is used when referring a vocabulary term?  How we write a filter over a property that can be of several possible types (either because of polymorphism or >)?  How can we infer unit of measurement?

13 Two aspects  Property metadata How we document property (uom, term list, semantic)  Property reference How do we identify a property ? Is this enough ?

14 Complex value  Try not to change WFS operation  Let « old » client work « new » client ingests new information  Externalise the solution  Use existing technology

15 Schema  Requirement 1. All operations that return a community schema shall only return references (import statements) to the original locations of community schemas.  Requirement 2. A schema describing a queryable resource must include all relevant xsd:import to allow discovery of all queryable extensions of the exposed resource.  Requirement 3. Import statement shall use absolute paths.  Recommendation 1. When a specific type is requested, all sub types from another namespace should be casted using xsi:type to the namespace of the request type.

16 Property reference An example from GeoSciML is the lithology property that is bounded to a vocabulary. The vocabulary used in the context of a map : (MappedFeature/specification/GeologicUnit/composition/Compo sitionPart/material/RockMaterial/lithology) can be different from the same property in a borehole context : (Borehole/MappedInterval/specification/ GeologicUnit/composition/CompositionPart/material/RockMater ial/lithology)

17 Property reference  Requirement 4. Reference to property must be expressed using the service location, the method, and the context type following the syntax {serviceURL}/{Method}/{contextFeature}/{path}  Requirement 5. When a property reference might contain substitution, the path shall use '*' in place of substitutable elements  Requirement 6. When more than one reference property matches a target path, the reference with the less degree of freedom shall be used.  Requirement 7 : A property that refers to a feature shall accept xlink:href syntax to represent this association  Requirement 8. Property metadata shall be expressed in SWECommon  Requirement 9. Property metadata shall have a mandatory identifier  Requirement 10. Property metadata shall use HTTP URI as unique identifier

18 Property reference  Recommendation 2. property that links a property to a SWE description shall be named ogc:propertyMetadata  Recommendation 3. inverseOf ogc:propertyMetadata shall be ogc:property

19 Data record

20 Date record  Requirement 11. Complex value shall be expressed in valid swe:Record  Requirement 12. A reference to a DataRecord component shall be expressed using field names as proxies for literal path  Requirement 13. The filter shall always target the XML encoding  Requirement 14. When a service realises that an inadequate vocabulary has been used, it shall raise an exception  Requirement 15. An error following the usage of the wrong dictionary shall identify the faulty dictionary and the property path used in the filter.  Recommendation 4. A compliant service shall have an extension in their GetCapabilities where dictionary reference are explicitly listed.  Requirement 15: Vocabulary shall be available in RDF representation  Requirement 17: Each term shall be identified by a HTTP URI  Recommendation 5. Vocabulary should be available in SKOS.

21 Data record  Requirement 18: Term used in the filter shall be the full HTTP URI of the term  Requirement 19: Property that are controlled by a vocabulary shall be documented by a swe:Category  Requirement 20: Category swe:identifier shall be a unique identifier for this vocabulary mapping  Requirement 21: swe:codeSpace shall be a reference to the SKOS collection http://ngwd-bdnes.cits.nrcan.gc.ca/Reference/uri-cgi/classifier/ca.on/Vocabulary/OntarioWaterWellLithologies Ontario lithologic vocabulary List of lithologic terms use in their water well database http://ngwd-bdnes.cits.nrcan.gc.ca/Reference/uri-cgi/classifier/ca.on/lithology/442

22 Remaining issues  Ordinal terms  Complex knowledge  Rob,Boyan and now Simon (in unison) : Ontology reasoning (and query expansion)

23 OWS Context  OGC® OWS-7 Information Sharing Engineering Report  OGC 10-035r2  WMC (Web Map Context) in steroid  Based on Atom (RSS type of file)  Pointed to by D. Arctur when we whined about WMS / WFS / SOS binding in GWIE  Ongoing (can be influenced ?)

24 Different implementations  1G is « client knows » Specific client that reads from the catalog and redirects GFI to information service  GSML TB 3 « client knows » Specific client knows where the get the WFS URL in the capabilities document.  GIN « mediator knows » Mediator wraps WMS service and intercepts requests

25 OWS Context application state  The principle use case for an OWS Context document is for defining the application state of an Integrated Client. When this application state is reproduced by two or more Integrated Clients, such clients are said to share a common operational picture.

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27 Collection of Resources Vocabulary ?

28 Context UML (as for 5 hrs ago)


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