The Uphill Battle of Semantic Interoperability

1. The Uphill Battle of Semantic Interoperability Roy WilliamsCalifornia Institute of Technology

2. A semantic web of interoperable resources rather than THE TOWER OF BABEL This talk: 1. Services 2. Vocabularies & Translation 3. Standard services

3. Example Service • Web Services • Structures in and out • Self-defined (WSDL) • Exceptions Client interface Server name= M51 x= 10 y= 10 sky_survey=DSS2_red mime_type=download_gif Request: Keyword/value http://archive.eso.org/dss/dss/image Response: image/gif

4. Networks of Services Catalog Service Query Check Service Query Estimator Archive Service User’s code Crossmatch Service Archive Service Storage Service What does the service do? Who is responsible? How can I use the service from Perl/Java/C++? What can I get from the service? What are the keywords, their meanings?? What values can they take? What authentication do I need?

5. DATE_OBS, DATE_END, DEL_TIME, EXPTIME, …. SOHO FITS file Line, Point, Symbol, Text, … drawing service RA, Dec, Long, Lat, … cutout service Curation: title, author, … FITS Image Service/File Shape • Each service has a shape • Defined by a combination of labels from a vocabulary • NVO works with community on standardizing the “bricks”

6. File Shape: FITS keywords • FITS keyword lists • This is the heart of astro interop today….. • VO will have registry of these “file shapes”?

7. right ascension declination magnitude Resource Interoperability Producer Consumer ? result Drawing Program

8. ID POS_EQ_RA_MAIN POS_EQ POS_EQ_DEC_MAIN Cone Search Registry A collection of services that have the same shape URLbase RA=200&DEC=20&SR=2 Request: HTTPget of shape: Response: VOTable of shape:

9. Cone Search + Density Probe baseURL Spacing Search radius Density Probe interoperating NVO-compliant services! Cone Search Far infrared, Finkbeiner et al

10. program user form service TITLE CREDIT dataset SHORT DESCRIPTION LONG NVO: curation NAME CONTACT EMAIL URL DISCLAIMER Semantics with UCD Templates ID POS_GAL_LON POS_GAL NVO: locatedSource POS_GAL_LAT POS POS_EQ_RA_MAIN POS_EQ POS_EQ_DEC_MAIN

11. UCD for Curation IVOA:CURATION_TITLE SHORT IVOA:CURATION_PUBLISHER LONG IVOA:CURATION_CREATOR SHORT IVOA:CURATION_DESCRIPTION LONG IVOA:CURATION_CONTRIBUTOR IVOA:CURATION_IDENTIFIER NAME IVOA:CURATION_CONTACT EMAIL IVOA:CURATION_URL IVOA:CURATION_ACKNOWLEDGEMENT CAN WE AGREE THIS PROTOCOL NOW?

12. Namespace = mydomain.com/furniture Namespace = mydomain.com/word-processing FITS keywords have no namespace! This is a URI (NOT a URL). A URI is a unique string. A URL is an address on the Internet. Namespaces “We took the table and chair dimensions, and wrote them in a table.”

13. Resource Interoperability Producer CDSDRAW mapping Consumer DRAW:X Drawing Program result DRAW:Y DRAW:SIZE VOSchema (Plante)

14. Ontology Mapping Horse Pig Sheep Cochon Mouton Cheval The translation is possible if we are talking about the same things

15. Ontology Mapping ? Horse Pig Sheep Voiture Bateau Bicyclette The mapping fails if it is impossible!

16. VO Services A service may be described by a SD, expressed in a SDL Inputs and outputs are hierarchical keyword/value set stream of VOTable records stream of XDF objects • A resource is a set of services that include • Send description • Send curation • Send query SDL • Send query registry registry resource • Every registry is a resource • returns lists of resources curation service service

17. “Send resource list” “Send service list” “Send Query-SD” client client resource service “Here is the SDL” “Here is my list” “Here is my list” Give resourceswith keywords client service Here is my list client service Give curation data Here are its params Elements of Conversation client registry

18. Astronomy Conversation • Do you speak VO version 3.5.2? • If you have catalogs, give me the list. • Give me the schema for catalog X • Give me query mechanisms (service types) • Answer this query on catalog X CAN WE AGREE THIS PROTOCOL NOW?