1. www.g-vo.org SimDB as a TAP service various TIG members (IVOA.IVOATheorySimDB)IVOA.IVOATheorySimDB

2. www.g-vo.org Overview History of SimDB SimDB is a TAP service –protocol –metadata Object relational mapping TAP as information integration protocol

3. www.g-vo.org History Simple Numeric Access Protocol (SNAP) –Cambridge 2006 –Victoria 2006 follow DAL v2 S*AP (ala SSAP) –data model –queryData –getData (accessURL) LARGE simulations (3+1D/ cosmological/...) –too large for accessURL –getData more complex: cut-outs etc Separated in 2 –Simulation database (SimDB) –Simulation Data Access Protocol (SimDAP)

4. www.g-vo.org SimDB SimDB is a protocol for a database containing metadata about simulations –like a Simulation registry (DONT MENTION REGISTRY) SimDBs data model (SimDB/DM) prescribes the databases data model Should support discovery of simulations, i.e. queryData of SNAP –query expressions –result format

5. www.g-vo.org SimDB/DM relatively complex (see tomorrow)

6. www.g-vo.org SimDB/TAP Claim: such a omplex model requires flexible query language –Choose ADQL Consequently(?) SimDB is a TAP service Special: Predefined data model Restrictions on required functionality –sync-only ADQL queries mandated –no upload –... (discuss tomorrow, TIG session) TAP 0.5, p10, comment about inheriting services

7. www.g-vo.org SimDB/TAP_SCHEMA Requires relational model for SimDB/DM –Object-Relational mapping –Impedance mismatch –some standard approaches Expressed as –VODataService –TAP_SCHEMA inserts –empty VOTable VOTable serialisation of the TAP_SCHEMA tables

8. www.g-vo.org OR mapping class table attribute column reference foreign key composition foreign key to container inheritance

9. www.g-vo.org class table CREATE TABLE t_Experiment ( ID BIGINT NOT NULL, -- Surrogate key publisherDID VARCHAR(128) NOT NULL,... ) ALTER TABLE t_Experiment ADD CONSTRAINT pk_t_Experiment_ID PRIMARY KEY(ID);

10. www.g-vo.org attribute column CREATE TABLE t_InputParameter ( ID BIGINT NOT NULL, name VARCHAR(128) NOT NULL, ucd varchar(128, datatype varchar(32) NOT NULL, multiplicity varchar(10),... ) Note: data type mapping required

11. www.g-vo.org reference foreign key CREATE TABLE t_Experiment ( ID BIGINT NOT NULL, protocolID BIGINT NOT NULL,... ) ALTER TABLE t_Experiment ADD CONSTRAINT fk_t_Experiment_protocol FOREIGN KEY (protocolId) REFERENCES t_Protocol(ID);

12. www.g-vo.org composition foreign key to container CREATE TABLE t_Column (... containerId BIGINT NOT NULL, -- Table... ); ALTER TABLE t_Column ADD CONSTRAINT fk_t_Column_container FOREIGN KEY (containerId) REFERENCES t_Table(ID);

13. www.g-vo.org inheritance Requirement: Each class, abstract and concrete, can be queried on –select * from Simulation –select * from Experiment –Select * from Resource Obtains all attributes, including inherited ones.

14. www.g-vo.org inheritance Some standard approaches 1.1 table per class, no inherited attributes primary key = foreign key to base table 2.1 table per hierarchy gather columns from subclasses DTYPE column 3.1 table per concrete (= non-abstract) class, all attributes

15. www.g-vo.org inheritance following 1 CREATE TABLE t_Resource ( ID BIGINT IDENTITY NOT NULL, DTYPE VARCHAR(32),... ); CREATE TABLE t_WebService ( ID BIGINT NOT NULL,... ); ALTER TABLE t_WebService ADD CONSTRAINT fk_t_WebService_extends FOREIGN KEY (ID) REFERENCES t_Resource(ID);

16. www.g-vo.org Add views, one per class CREATE VIEW Resource AS SELECT ID, DTYPE, name, description, referenceURL, created, updated, status FROM t_Resource CREATE VIEW WebService AS SELECT b.*, t.baseURL, t.type, t.registryId FROM t_WebService t, Resource b WHERE b.ID = t.ID

17. www.g-vo.org Comments (discussed tomorrow) Implementations in progress Heterogeneity and quantities cause problems for ADQL –Albertos proposal might help: fix units for quantities (defined by vocabulary) –May need simpler, dedicated protocols How to register SimDB/TAP? Extensions to DM allowed? SimDB/REST+XML as well? VOExplorer-like approach to browsing a SimDB

18. www.g-vo.org Conclusions Approach might be used for –SIAP, SSA, Registry Not for –STC, Characterisation Is (??) already used/planned for –Atomic/molecular lines, Source catalogue Complexity of SimDB caused be heterogeneity –simpler for other cases Finally, need participation in SimDB effort.