1. 2007-04-12/13SNAP data model Simulation data model

2. 2007-04-12/13SNAP data model Overview Goal and approach Domain model Logical model Discussion Other data models –IVOA –Concrete Usage in query protocol

3. 2007-04-12/13SNAP data model Goals Describe spatial simulations for SNAP ( SSSAP ?) Use in –Discovery (simulation registry) –Query phase in SSSAP protocol –Meta data in returned data See whether we can produce a model serving other types of simulations as well.

4. 2007-04-12/13SNAP data model Modeling approach Step 1: Analyse universe of discourse, resulting in a domain model : –Application independent –Implementation (language) neutral (UML) Step 2: Specialise to requirements, create logical model –Application dependent –Implementation neutral (UML) Step 3: create mappings to implementation languages, physical model: –XML schema –Relational database schema

5. 2007-04-12/13SNAP data model Simulation domain model Based on domain model for astronomy http://www.ivoa.net/internal/IVOA/IvoaDataModel/Domai nModelv0.9.1.doc http://www.ivoa.net/internal/IVOA/IvoaDataModel/Domai nModelv0.9.1.doc Main areas/namespaces: –Experiment –Protocol –Phenomenology –Storage –Standards –Model

6. 2007-04-12/13SNAP data model Domain model overview

7. 2007-04-12/13SNAP data model Domain model packages

8. 2007-04-12/13SNAP data model Domain model experiment

9. 2007-04-12/13SNAP data model Domain model protocol

10. 2007-04-12/13SNAP data model Domain model phenomenology

11. 2007-04-12/13SNAP data model Experiment:simulation Protocol::simulation

12. 2007-04-12/13SNAP data model Logical model Not aim to describe all details of simulations, nor all types of simulations Focus on those aspects of interest to –discover interesting SNAP services –query a SNAP service for interesting simulations –provide meta data for a data product produced by SNAP service How to find out? Ask scientists (as well as ourselves)!

13. 2007-04-12/13SNAP data model Example questions What questions would you ask a database containing (meta-data about) simulations: –What is simulation about? –What physical processes are implemented? –What values do certain parameters have? –What observables are provided? –What are characteristics of observables? –What type of data products can be returned? –What special data products can be provided as well? –What special services are available on server?

14. 2007-04-12/13SNAP data model Logical model For our purposes (SNAP), a simulation is the execution of software that produces a representation of a spatial system, and possibly follows its evolution in time by approximating the true physical processes of the system with numerical algorithms.

15. 2007-04-12/13SNAP data model Logical model (see wiki page and doc)

16. 2007-04-12/13SNAP data model Discussion SNAP_DataModel.doc SNAP_DataModel.doc

17. 2007-04-12/13SNAP data model Relations to other DMs DM WG –CharacterisationCharacterisation –Quantity (?!)Quantity Resource Registry WG –Resource MetadataResource Metadata Semantics WG –UCDUCD –standard vocabularystandard vocabulary –Ontology of astronomical object typesOntology of astronomical object types

18. 2007-04-12/13SNAP data model Characterisation We have a generalisation of (part of?) characterisation –a priori and a posteriori –No support/fill, do we need it? How? –No accuracy/sensitivity, do we need it? How? How do we proceed? –use Characterisation patterns –use implementation ACTION ITEM –tiger team to complete this aspect of model

19. 2007-04-12/13SNAP data model Resource Metadata Registration of SNAP resources Registration of related services Description of simulations published through SNAP sufficient? ACTION ITEM –tiger team for proposing how/what to register

20. 2007-04-12/13SNAP data model Semantics Various usages of standard vocabularies, ontologies Are the current lists sufficient for SNAP+Simulation description/querying? What is missing? ACTION ITEM –tiger team to evaluate this –propose more concepts –push for getting such lists accepted in IVOA

21. 2007-04-12/13SNAP data model Quantity (?) Could this DM play a role in defining how different data products are stored? Can be retrieved? Possibly suggest standard representations for complex data structures. Possibly suggest bindings to various popular languages. Opinions...?

22. 2007-04-12/13SNAP data model Mapping of concrete models Need to validate our model by checking whether concrete models out there are properly supported –ITVO data modelITVO data model –Horizon data modelHorizon data model –GalICS data modelGalICS data model –Data model from OWLS-GIMIC HDF-5 filesData model from OWLS-GIMIC HDF-5 files –GAVO hydrosims data modelGAVO hydrosims data model –Millennium database data modelMillennium database data model –Example input parameter filesExample input parameter files

23. 2007-04-12/13SNAP data model Usage of data model Query protocols –HTTP –ADQL Serialisation –XML schema –Relational database schema

24. 2007-04-12/13SNAP data model HTTP GET Parameter-value based Not simple if underlying model complex (or is it?) At least not in one query use multiple queries: drill-down Requires more sophisticated (web) applications, possibly session aware. Useful to have this done in a centralised meta data repository.

25. 2007-04-12/13SNAP data model ADQL SQL based Requires relational mapping (see later) Requires supporting a relational database as well as ADQL Again, useful to have a limited number of meta-data repositories (registry++?).

26. 2007-04-12/13SNAP data model Mappings (see doc) XML schema –Mapping prescription ( http://www.ivoa.net/twiki/bin/view/IVOA/VOResource010RevNotes ) http://www.ivoa.net/twiki/bin/view/IVOA/VOResource010RevNotes –Can be automated (XSLT or ArchitectureWare from XMI files) Relational model –Simpler and rather many standards for OR mapping (JDO, Hibernate) –For ADQL/TAP? need some extra files to provide database metadata If agree on mappings, both can be postponed until UML is done.

27. 2007-04-12/13SNAP data model How to proceed.

28. 2007-04-12/13SNAP data model TODO items Previously mentioned teams for ironing out certain issues wrt other IVOA efforts –characterisation –ontologies –registry model –quantity Test cases –map concrete models to SNAP model –implement services Gather feedback from community –explanatory document –questionnaire –incorporate comments –Euro-VO DCA TEG