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

7 SCAS: get service chain description The operation getServiceChain (ID) provides MetaInformation on the chain and a link to the service chain description getService Chain 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 Scenario - Forest Fires - Pilot Application – Thematic Focus 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 forest fires aggregated by administrative unit –Forest fire density: forest fire frequency normalised by area –Forest fire risk: forest fire density classified into risk classes

10 Pilot Application – Conceptual Level 1.Access –Fire records from EU Member States –Schema mapping 2.Spatial and temporal aggregation –Based on Administrative Units –Or based on European Grid 3.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 data passed by value Cascaded control flow (e.g. WPS) Centralized control flow and data passed by value =separation of control and data flow BPEL + storage functionalities

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