© Roy Williams 2002 The Uphill Battle of Semantic Interoperability Roy Williams California Institute of Technology

© Roy Williams 2002 A semantic web of interoperable resources rather than THE TOWER OF BABEL This talk: 1. Services 2. Vocabularies & Translation 3. Standard services

© Roy Williams 2002 Example Service name=M51 x=10 y=10 sky_survey=DSS2_red mime_type=download_gif Client interface Request: Keyword/value Response: image/gif Server Web Services Structures in and out Self-defined (WSDL) Exceptions

© Roy Williams 2002 Networks of Services 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? Storage Service Archive Service Catalog Service User’s code Crossmatch Service Archive Service Query Check Service Query Estimator

© Roy Williams 2002 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” Line, Point, Symbol, Text, … drawing service SOHO FITS file DATE_OBS, DATE_END, DEL_TIME, EXPTIME, …. RA, Dec, Long, Lat, … FITS Image cutout service Curation: title, author, …

© Roy Williams 2002 File Shape: FITS keywords FITS keyword lists This is the heart of astro interop today….. VO will have registry of these “file shapes”?

© Roy Williams 2002 Resource Interoperability Right Ascension (degrees) Declination (degrees) Magnitude (mags) Drawing Program right ascension declination magnitude result ? Producer Consumer

© Roy Williams 2002 Cone Search Registry POS_EQ_RA_MAIN POS_EQ_DEC_MAIN POS_EQ ID URLbase RA=200&DEC=20&SR=2 Request: HTTPget of shape: Response: VOTable of shape: A collection of services that have the same shape

© Roy Williams 2002 Cone Search + Density Probe Far infrared, Finkbeiner et al Cone Search Density Probe baseURL Spacing Search radius interoperating NVO-compliant services!

© Roy Williams 2002 Semantics with UCD Templates program user form service dataset POS_GAL_LON POS_GAL_LAT POS_EQ_RA_MAIN POS_EQ_DEC_MAIN POS_EQ POS_GAL POS ID NVO: locatedSource CREDIT DESCRIPTION TITLE CONTACT SHORT LONG NAME NVO: curation URL DISCLAIMER

© Roy Williams 2002 UCD for Curation IVOA:CURATION_IDENTIFIER IVOA:CURATION_DESCRIPTION IVOA:CURATION_CREATOR IVOA:CURATION_CONTACT SHORT LONG NAME IVOA:CURATION_URL IVOA:CURATION_ACKNOWLEDGEMENT IVOA:CURATION_PUBLISHER IVOA:CURATION_TITLE IVOA:CURATION_CONTRIBUTOR SHORT LONG  CAN WE AGREE THIS PROTOCOL NOW?

© Roy Williams 2002 Namespaces “We took the table and chair dimensions, and wrote them in a table.” Namespace = mydomain.com/furniture Namespace = mydomain.com/word-processing This is a URI (NOT a URL). A URI is a unique string. A URL is an address on the Internet. FITS keywords have no namespace!

© Roy Williams 2002 Resource Interoperability Right Ascension CDS:POS_EQ_RA_MAIN Declination CDS:POS_EQ_DEC_MAIN Magnitude CDS:PHOT_MAG Drawing Program DRAW:X DRAW:Y DRAW:SIZE result Producer Consumer CDS  DRAW mapping VOSchema (Plante)

© Roy Williams 2002 Ontology Mapping Horse Pig Sheep Cochon Mouton Cheval The translation is possible if we are talking about the same things

© Roy Williams 2002 Ontology Mapping Horse Pig Sheep Voiture Bateau Bicyclette ? The mapping fails if it is impossible!

© Roy Williams 2002 VO Services Every registry is a resource returns lists of resources 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 resource curation service

© Roy Williams 2002 Elements of Conversation client registry “Send resource list” “Here is my list” service “Send Query-SD” “Here is the SDL” client service Give resources with keywords Here is my list client service Here are its params Give curation data client resource “Send service list” “Here is my list” client

© Roy Williams 2002 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?