Recent Advances in Geospatial Service Chaining Open Standards 2008 Composability within SOA...

Recent Advances in Geospatial Recent Advances in Geospatial Service ChainingService Chaining

Open Standards 2008

Composability within SOA Symposium

April, 2008

Raj Singh, PhD

<[email protected]>

OGC Director of Interoperability Programs

AgendaAgenda

• Background on OGC• OGC Test beds and OWS-5, the workflow test bed• Background on the domain problem – Conflation• The added complexity of cross-organization interoperability• The solution: OGC Web Services and BPEL workflow

2Helping the World to Communicate Geographically Copyright © 2008, Open

Geospatial Consortium, Inc., All Rights Reserved

OGC, the OrganizationOGC, the Organization

Everything happens somewhere – and “somewhen”!Everything happens somewhere – and “somewhen”!

• …it’s estimated that 80 to 90% of all data maintained or archived in databases has some geographic property!

• Can anyone think of an activity that does not have the properties of geographic location and time, or that impacts a location over time?



The ChallengesThe Challenges

• Discovery: These data are distributed in tens of thousands of repositories

• Access: They will never, ever be put into massive centralized repositories

• Processing and fusion: These data typically must be processed in order to be useful for the end-user application

• Decision makers, policy makers, scientists, researchers, consumers, emergency response – all need access to the latest and best geo content and services – when and where they need it!



OGC SnapshotOGC Snapshot

• A not-for-profit, voluntary, consensus Standards Organization founded in 1994

• To serve as a global forum for the development, promotion and harmonization of open and freely available geospatial standards

• Currently ~350 member organizations• Twenty four adopted standards• Four OGC Standards are now also ISO Standards



Alliance PartnershipsAlliance PartnershipsCritical To Successful Standards Development and ImplementationCritical To Successful Standards Development and Implementation

and others…



OGC’s Foundation Data Access StandardsOGC’s Foundation Data Access Standards

• WMS: Web Mapping Service: web images of maps

• WFS: Web Feature Service: vector data

• WCS: Web Coverage Service: raster imagery and grids

• GML: Geography Markup Language: XML encoding of data

• SOS: Sensor Observation Service: real-time data

• CSW: Catalogue Service for the Web: geospatial search

• WPS: Web Processing Service: run a model/algorithm/process



But now we must combine them into But now we must combine them into processing and fusion servicesprocessing and fusion services

Source: Broadstroke



The OGC Interoperability ProgramThe OGC Interoperability Program& OWS-5& OWS-5

OGC’s Approach for Advancing InteroperabilityOGC’s Approach for Advancing Interoperability

• Interoperability Program (IP) - a global, innovative, hands-on prototyping and testing program designed to accelerate interface development and validation, and bring interoperability to the market

• Specification Development Program –Consensus processes similar to other Industry consortia (World Wide Web Consortium, OMA, OMG, etc.).

• Outreach and Community Adoption Program – education and training, encourage take up of OGC specifications, business development, communications programs

Rapid InterfaceDevelopment

StandardsSetting

MarketAdoption



Testbeds Enhance StandardsTestbeds Enhance Standards



Examples of Interoperable (Open) Examples of Interoperable (Open) Geospatial Service ChainingGeospatial Service Chaining

Why?Why?

• Large data sets: up to terabytes• Issues of provenance• Organizational information management



Imagery Processing WorkflowImagery Processing Workflow

…

Internet

OGC Interfaces

Service chaining creates value-added products from SWE Observations

WCS = Web Coverage ServiceWCTS = Web Coordinate Transformation ServiceWPS = Web Processing Service

SOS WCTS WPS WFS

decision supportclient



Data Reduction WorkflowData Reduction Workflow

Steven Keens, PCI



Use Case: workflow for geospatial Use Case: workflow for geospatial data conflationdata conflation

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Conflation Use CaseConflation Use Case

• Conflation is the process of unifying multiple separate sources of data into one integrated all-encompassing result

• Conflation is a complex task with many variations and rules that guide the discovery and combination of features

Helping the World to Communicate Geographically Copyright © 2008, Open Geospatial Consortium, Inc., All Rights Reserved

Conflation Use CaseConflation Use Case

• Preserve geometry connectivity (vertical red to green, upper center right)

• Resolve potential overshoot issues (unique red feature, middle center right)

• Conflate attributes



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Issues in ConflationIssues in Conflation

• Metadata• Lineage: the origins of each feature must be retained • Absolute Horizontal Accuracy: spatial accuracy relative to true location

• Feature Type: Feature description information• Alignment: Spatial agreement among features• Competition: choice of alternatives when determining common features • Geometry: point, line, area (polygon) and other geometries • Coordinate Specification: issues associated with potential differences• Duplicate Features: duplication in coordinates and/or attribute values• Schemas: differences in description of attributes, data type, units of measure, domain• Feature Association

• full feature matching: association made on complete features only

• partial feature matching: only a subset of a feature associates to a feature in the other data set

• single feature matching: matched exclusively on a one-to-one basis, in whole or part

• multi-feature matching: any given feature in one source matches to several in the other


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Families of Conflation Business RulesFamilies of Conflation Business Rules

MatchingSimilarity Selection

To find the same features and attributes

Feature Types - Names and Codes

Schema – attribution names, units, enumeration

To match two or more features

Geometry/location – accuracy and tolerance

Attribute matching values, null/unknown attribute value

Feature Type matching

Geometry Type matching

To select the Quality of the resultant features

Quality preference rules

Join/Merge attribute precedence and conversion of expected output

All of the common Conflation Tools have some form of business rule definition and logic that is applicable to these families of rules.


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Rules as Web ServicesRules as Web Services


Workflow deployment strategyWorkflow deployment strategy

• Idealized– Rules are web services– BPEL describes rules

application– Client has a rule editor

• Pick rules from a GUI• Build a BPEL workflow

• Actual– Rules are processes– BPEL describes calling a

Web Processing Service– WPS is a web services

wrapper for rules

23Helping the World to Communicate Geographically

Copyright © 2008, Open Geospatial Consortium, Inc., All Rights Reserved

Web Processing ServiceWeb Processing Service

WPS

WPS-client

Web Processing Service

GetCapabilities DescribeProcess Execute

Algorithm Repository

……

Algorithm 1

…

…Data Handler A

Data Handler Repository

Communication over the web using HTTP



Deployment of Conflation Services – IdealDeployment of Conflation Services – Ideal



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Deployment of Conflation Services – ActualDeployment of Conflation Services – Actual

BPEL Engine

WPS

WFS

WFS

Radius Studio™

Source data

Template Rules (xml)

Results (xml)

Parameterised Rule (xml)

Result Data

Client

GML 3.2.1

GML 3.2.1

SOAP request

SOAP response

WFSGML 2

HTTPGet/Post

SO

AP


27

Lessons LearnedLessons Learned

• BPEL + OGC Web Services works

• Initial hurdles were hard, so we only have simple workflows– SOAP-WSDL for all OGC services– SOA for rules

• Future work items– More complex workflows– More detailed WPSes


Recent Advances in Geospatial Service Chaining Open Standards 2008 Composability within SOA...

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