WS-GIS: Towards a SOA-Based SDI Federation

Fábio Luiz Leite JúniorInformation System LaboratoryUniversity of Campina Grandefabio@dsc.ufcg.edu.brhttp://www.lsi.dsc.ufcg.edu.br

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Outline

Introduction Architecture Example Scenario Conclusion and Further work

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Introduction

The increasing of spatial digital data Petabytes / year in satellite images Digital maps Use of maps in mobile devices

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Main issues: Spatial-aware search engines Data replication should be minimized The use of standards is mandatory

Spatial Data Infrastructure Global, national, and local scale, Using semantic Based on Service-Oriented Architecture

Introduction

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Introduction

SDI – “Technologies, policies, and people necessary to promote sharing of geospatial data throughout all levels of government, the private and non-profit sectors, and the academic community”.

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Introduction

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Introduction

... in the spatial domain base maps, coordinate transformation,

gazetteer, location-based systems, routing, overlay, buffer

how to find out precisely the service a user is requesting ? Keyword-based search ?

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Introduction Web services limitation:

UDDI registry contains little textual information about the underlying services

Keyword-based search may retrieve many irrelevant services just because they contain the addressed keyword

WSDL and UDDI descriptions express almost none of the service semantics

When dealing with spatial data these directories should become spatial-aware

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Our proposal – WS-GIS

A Spatial Data Infrastructure based on SOA for data and services sharing

Users may query a distributed catalog service, semantically enhanced with ontologies

WS-GIS enables spatial search on distributed catalog

Data sharing through some SDI

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Architecture

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Architecture Semantic integration among catalogues

Each SDI defines its own ontology that is used in its catalogues

Assumption: there is a set of concepts which can be shared among the SDIs Clustering semantic communities [Hameed et

al, 2004] Communities are formed through semantic

mapping between SDIs Catalogues that receive the propagated

query make the semantic mapping between the local ontology and the global one

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Semantic integration among catalogues

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Architecture

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ArchitectureService

Description Tool

Service Description

Tool

Geographic MatchmakerFunctionalities

Geographic MatchmakerFunctionalities

Query Propagation

Query Broker

Ontology Reconciliation

Service Providers

Service Designers

Semantic Web servicedescriptions (OWL-S)

Description Repository

SDI Ontology

fin

d W

eb s

erv

ices

submit queries

uses

uses

Service Description

Tool

Service Description

Tool

Geographic MatchmakerFunctionalities

Geographic MatchmakerFunctionalities

Query Propagation

Query Broker

Ontology Reconciliation

Service Providers

Service Designers

Semantic Web servicedescriptions (OWL-S)

Description Repository

SDI Ontology

fin

d W

eb s

erv

ices

submit queries

uses

uses

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Architecture

The catalog service is the core of our architecture Responsible for SDIs integration at local,

national or international scope Each SDI maintains a spatial-aware

catalogue which may find resources locally Communication protocol which propagates

rewritten queries to other SDI catalogues Strategy to maintain the federation Comply with OGC Catalogue API standard

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Example Scenario

Suppose that a user would like visualize a SVG map Regions of Paraíba (AESA) Rivers (and water quality) in Sertão

region (SUDEMA) Roads of the entire state (DER)

AESA SDI Contains Gazetteer service Map conversion service (GML - SVG)

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Example Scenario

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Conclusion

This is a work in progress WS-GIS architecture which aims to

implement a SOA-based SDI A set of spatial services and a federation

of catalogues to enable distributed queries Main purpose

to enable integration of heterogeneous spatial data sets,

by promoting interoperability, flexibility and service chaining

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Further Work

To improve the workflow service Load balancing, Quality of service monitoring, Data provenance and service context

Automatic ontology reconciliation To extend to mobile GIS applications Performance evaluation To analyse the use of grid computing in

our architecture

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Thank you very much!

Questions?