WS-GIS: Towards a SOA-Based SDI Federation

1. Fábio Luiz Leite Júnior Information System Laboratory University of Campina Grande fabio@dsc.ufcg.edu.br http://www.lsi.dsc.ufcg.edu.br WS-GIS: Towards a SOA-Based SDI Federation

2. Outline Introduction Architecture Example Scenario Conclusion and Further work

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

4. 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

5. 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”.

6. Introduction

7. 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 ?

8. 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

9. 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

10. Architecture

11. 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

12. Semantic integration among catalogues

13. Architecture

14. Architecture

15. 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

16. 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)

17. Example Scenario

19. 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

20. 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

21. Thank you very much! Questions?