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Service composition

Service composition. Roberto Lucchi joint work with Anders Friis-Christensen, Michael Lutz and Nicole Ostlaender European Commission – DG Joint Research Centre Spatial Data Infrastructure Unit Ispra, Italy. Outline. ORCHESTRA Service chaining and Service Chain Access Service Pilot

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Service composition

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  1. Service composition Roberto Lucchi joint work with Anders Friis-Christensen, Michael Lutz and Nicole Ostlaender European Commission – DG Joint Research Centre Spatial Data Infrastructure Unit Ispra, Italy

  2. Outline • ORCHESTRA • Service chaining and Service Chain Access Service • Pilot • Control flow and data flow patterns • Related issues

  3. ORCHESTRA – Goals • Develop and test interoperable software architecture for risk management applications • specify interoperable risk management services • input to standardisation (OGC, ISO, CEN…) • Role JRC–IES: • Technical supervisor • Pilot development within two application areas (forest fires and flooding)

  4. ORCHESTRA pilot: Pan-European Assessment of Natural Hazards • Implement distributed geo-processing for • Forest Fire Risk analysis • (Flood) Damage assessment • by chaining existing ORCHESTRA (SOAP) services • Feature Access Service (FAS) • Map Access Service (MAS) • Processing Service (PS) • in a new (risk specific) service executing the workflow FAS  OGC WFS MAS  OGC WMS PS  OGC WPS

  5. Service Chaining in ORCHESTRA • ISO 19119 Opaque chaining (aggregate services) • Hide the business logic • Service chain instance functionalities can be re-used • Service chain descriptions based on BPEL • Usage of the Service Chain Access Service (SCAS) for • Managing service chain descriptions • Deploying the service chain instances in ORCHESTRA Service Networks • SCAS provides a means to: • getServiceChain: Get a service chain description • createServiceChain: Create a new service chain instance based on a chain description • deleteServiceChain: Delete service chain instances • getCapabilities

  6. SCAS SCAS client FFRA DA Catalogue MyChain Workflow Description <entry …> Height Difference Store Zonal Rating MyChain SCAS: Creating new service chains ORCHESTRA Services Network • CreateServiceChain request • Chain Description (M) : MyChain • Catalogue endpoint (O) : CatUrl Deploy Register the created service chain instance <entry …> <entry …> <entry …> <entry …> <entry …> <entry …> <entry …> <entry …>

  7. SCAS: get service chain description • The operation getServiceChain (ID) provides MetaInformation on the chain and a link to the service chain description getServiceChain Sample response • Requesting existing service chain descriptions can be used to: • Re-deploy in different ORCHESTRA service networks • Modify existing workflows (use new services, different techniques)

  8. Pilot Application – Thematic Focus Scenario - Forest Fires - • Assessing natural hazards and related risks

  9. Pilot Application – Requirement Analysis • End users: Domain experts in the context of forest fires conducting policy support towards various EC DGs • Functionalities: • Interoperable access to heterogeneous MS fire records • Harmonisation of heterogeneous data into a common schema • Flexible and distributed Forest Fire Hazard and Risk mapping • Measures • Forest fire frequency: number of forestfires aggregated by administrative unit • Forest fire density: forest firefrequency normalised by area • Forest fire risk: forest fire densityclassified into risk classes

  10. Pilot Application – Conceptual Level • Access • Fire records from EU Member States • Schema mapping • Spatial and temporal aggregation • Based on Administrative Units • Or based on European Grid • Analysis • Fire frequency • Fire density • Fire risk classes

  11. Distributed Geoprocessing – Approach • Identify the processing tasks required to produce the requested analysis information • Define workflows producing the required information • Provide workflows execution as OT-Risk-Specific Services • implemented using opaque chaining (via BPEL) • the client applications use one single service

  12. Distributed Geoprocessing – Processing Tasks • Forest Fire Frequency • Spatial Join of Forest Fire Points with NUTS polygons • Counting joined points per NUTS polygon  Join and Aggregation service • Forest Fire Density • Normalizing Forest Fire Frequency by area of NUTS polygons  Normalisation service • Forest Fire Risk • Classifying risk based on forest fire density per NUTS polygon into risk classes  Classification service

  13. Distributed Geoprocessing in the Pilot Application

  14. Forest Fire Risk Assessment Service

  15. Control and data flow patterns • We also invetigated different chaining patterns and data passing modalities Centralized control flow and data passed by value =separation of control and data flow  BPEL + storage functionalities Cascaded control flow (e.g. WPS) Centralized control flow data passed by value

  16. Final remarks and open issues • No standard service chain interface • High flexibility, but complicates • clients development • service chain re-usability (and discovery) • Service chains conformance • getCapabilities: is it mandatory? • What kind of data reference mechanism? • URL • WPS and WCS 1.1 can store results and return a URL • getResourceByID (OWS Common 1.1.0) • Alternative interaction modalities • Asynchronous invocation of service chains

  17. Extra slides

  18. PS PS PS Join & Aggreg. Classification Map Algebra The ORCHESTRA Service Types and Taxonomy OA info-structure service FAS Catalogue MAS OA support service SCAS OT support service OT risk specific services Forest FireRisk Analysis Damage assessment FAS  OGC WFS MAS  OGC WMS PS  OGC WPS Obtained by chaining ORCHESTRA services

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