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JOINT RESEARCH CENTRE

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JOINT RESEARCH CENTRE Powered By Docstoc
					    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




                                                               1
                   Outline

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



                                              2
            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)

                                                     3
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)            FAS  OGC WFS

   – Map Access Service (MAS)                MAS  OGC WMS
                                             PS  OGC WPS
   – Processing Service (PS)
• in a new (risk specific) service executing the
  workflow
                                                        4
      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

                                                                    5
               SCAS: Creating new service chains
                                                        ORCHESTRA Services Network

               CreateServiceChain request
               • Chain Description (M) : MyChain
               • Catalogue endpoint (O) : CatUrl
SCAS                                                                       SCAS   Deploy
                                                                                           MyChain
client
                                                                                           FFRA
                                 Register the created                                      DA
    MyChain                      service chain instance
Workflow Description

 Height Difference
                                             Catalogue
                                         <entry …>   <entry …>
                                         <entry …>   <entry …>
                                         <entry …>   <entry …>
                                         <entry …>   <entry …> <entry …>


       Store



Zonal Rating

                                                                                              6
     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)
                                                                          7
    Pilot Application – Thematic Focus

• Assessing
  natural hazards
  and related risks
                         Scenario
                      - Forest Fires -




                                         8
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

                                                                    9
Pilot Application – Conceptual Level
1. Access
   – Fire records from EU Member States
   – Schema mapping
                                          cd Data Model


                                            ForestFireRegistration_Common




2. Spatial and temporal aggregation
                                             +   fireID: char
                                             +   dateAl: char
                                             +   timeAl: char
                                             +   timeIn: char
                                             +   dateIn: char
                                             +   dateEx: char



   – Based on Administrative Units
                                             +   timeEx: char
                                             +   codeCom: char
                                             +   nuts3: char
                                             +   nameCom: char
                                             +   tba: char



   – Or based on European Grid
                                             +   fba: char
                                             +   nfba: char
                                             +   cause: char




3. Analysis
   – Fire frequency
   – Fire density
   – Fire risk classes

                                                                            10
  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

                                                 11
 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


                                                                      12
                        Distributed Geoprocessing in the Pilot Application
                                                                                PEUNHA
                                                                                 Client


                                                                     (0) provide execution parameters

                              uses          MAS                                                                        FAS-X           uses
                                                              (6) render features
                                                                    in a map             (1) retrieve forest
                 Symbology                                                                  fire features                                 Mapping Rules to
                   Rules                                                                                               accesses           Common Schema
                                                                             Forest Fire
                                                   (5) classify                 Risk                                MS1 forest fire
                                                     features                Assessment                              registration
                         Classification
                 uses                                                                                                        MS2 forest fire
                            Service                         (4) normalise                        (2) retrieve admin.
                                                          features by area                          unit features
                                                                                                                              registration
Classification
   Rules
                                                                          (3) aggregate forest
                                                                              fire features
                                           Normalisation                    by admin. units                        FAS
                                             Service
                                                                                                                  accesses
                                                                           Join &
                             Processing
                                                                         Aggregation                           Administrative
                              Services
                                                                           Service                                units

                                          Client                              MAS = Map Access Service
                                          OA Info-Structure Service           FAS = Feature Access Service
                                          OT Support Service                  FAS-X = Translating FAS
                                                                                                                                                13
                                          OT Risk Specific Service
Forest Fire Risk Assessment Service




                                      14
              Control and data flow patterns
• We also invetigated different chaining patterns and data
  passing modalities
Centralized control flow   Cascaded control flow   Centralized control flow
data passed by value       (e.g. WPS)              and data passed by value
                                                   =separation of control and data flow
                                                    BPEL + storage functionalities




                                                                               15
         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
                                                             16
Extra slides




               17
   The ORCHESTRA Service Types and
             Taxonomy
OA info-structure service                          Catalogue                  FAS
                                MAS

OA support service                                                         SCAS


OT support service                      PS                                      PS
                                  Join & Aggreg.
                                                            PS            Map Algebra
                                                     Classification


OT risk specific           Damage                                       Forest Fire
services                assessment                                    Risk Analysis


FAS  OGC WFS               Obtained by chaining ORCHESTRA services
MAS  OGC WMS
                                                                                 18
PS  OGC WPS

				
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posted:9/29/2011
language:English
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