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1. Semantic Integration of Heterogeneous NASA Mission Data Sources
2. Goal: Virtual data integration Virtual Integration: enable construction of single virtual data source that presents a semantically unified view across a set of heterogeneous data sources
3. Outline Semantic Integration Basics
SemanticIntegrator (SI) Architecture
Application to Science Ops Planning
Conclusions
4. What is Information Integration? Integration involves:
bringing together information from multiple sources
synthesizing a unified view of the information
5. Syntactic vs. Semantic Integration Syntactic integration: integrate based on surface commonalities across data labels and values
Eg: correspond temperature field in one DB with temperature field in another based on identical field name and datatype (numeric)
Semantic integration : integrate based on commonalities in meaning behind data
Eg: correspond temperature fields based on the fact that both measure the same property of the same physical subsystem and their scientific units are compatible
6. Shallow vs. Deep Integration Shallow integration: retrieve the union of all potentially-relevant information from all data sources and present everything to the user (Google-like approach)
Deep integration: synthesize a single view from all available data sources and present that integrated view to the user
Requires defining a common integrated view of data
Requires identification and disambiguation of similar data across sources
Is challenging!
7. Deep, Semantic Integration Example
8. Ontologies: Key to Deep, Semantic Integration
9. Outline
10. Generic Integration Architecture
11. Integration Problems/Approaches
12. SemanticIntegrator Architecture
13. Outline
15. Mobile Agents Data Sources Field Data
Images of field sites, environ. features, mineral samples
Voice notes
Site data (lat/lon, topography)
Stored in ScienceOrganizer semantic repository
Analytic Data
Sample analysis data (e.g., composition)
Stored in Excel spreadsheet
Mineralogy Data
Chemical composition, atomic weight
Available @ minerals.com
GIS Data
Satellite images
Geographic data (e.g., population, features)
Available from Microsofts TerraServer Web service
16. Applying SemanticIntegrator to Mobile Agents 4 data sources
5 ontologies:
4 different ontologies to impart meaning to data sources
1 ontology represents the integrated source
Rules capture translations between sources
Simple interface to display integrated data (SIMA: SemanticIntegrator for Mobile Agents)
17. Ontologies
18. SIMA Interface
19. Outline
20. Conclusions Goal: avoid expensive hard-coded, one-off integration strategies
SemanticIntegrators explicit integration framework enables reuse of components and knowledge, reducing incremental integration overhead:
Data source wrappers/ontologies can be reused
Rules can be reused