Progress Report of VOQL WG

Progress Report of VOQL WG May 15 (Thu) Masatoshi Ohishi (Japan)

1. WG on 14th • About 20 people attended the WG: UK, US, Canada, Germany, France, ESA, Korea, Japan • Secretary: Bob Mann minutes – on TWiKi • 8 presentations • Succeeded to establish a human-network(layer 8) for our common goal.

2. Activities on QLs • 2 major trends • Extended SQL based QL • XML-based query

Extended SQL based QL • More than 90 % of astronomical DBs are RDBs, and SQL is used to query to DBs. • Functions are not sufficient to make access to federated DBs (e.g., multi- wavelength) with astronomical specific requests. • Prototypes are running. • Compact, and easy to learn.

EX. JVO QL • Retrieves catalog data and images from multiple data servers via a single user interface • Extension of SQL • Catalog.UCD • Box(Point(c1.ra,c1.dec), width1,height1) • XMATCH(c1,c2,!c3,…)< 3 arcsec • Select Catalog: Keyword1 & Keyword2 • Select by [[MAX|MIN](PROPERTY) | ALL] [NAME] • Area : [inside|outside] area0 • Area1 [overlap|union] area2 | shape • SHAPE: box, circle, oval, triangle,point • DIFF(x.obs_date, y.obs_date) > 30 days

XML-based QLs • Possible to make semantic expressions, but a QL file becomes larger than SQL-based QLs. • More generalized than SQL-based QLs. • It will take at least two years to finalize the basic delevopments. • XMLs are rapidly developling.

EX. Problem Statement Language • Return RA, Dec, Vmag for stars with 13<Vmag<15 and 10:12:53.5<RA<13:13:43 and 18:38:00<DE< 18:40:00. • PSL: <object class=“star”> <property name=“Vmag”> <range min=“13” max=“15”/> <value>?vmag</value> </property> <property name=“RA”> <range min=“10:12:53.5” max=“13:13:43”/>\ <value>?ra</value> </property> <property name=“DE”> <range min=“18:38:00” max=“18:40:00”/> <value>?de</value> </property> </object>

Agreement • Two level approach • Level-1 : Extended SQL-based QL as the first version, we develop a prototype by the end of 2003, and will revise by the end of 2004.(Wil O’Mullane and Naoki Yasuda) • Level-2 : Higher-level VOQL will be based on the XML-based QLs. Need to watch progress on XML-based QLs. (Ed Shaya and Patrick Dowler)

Cross-Match Cross-Match query Line-Match Meta-data Table Join ? SimpleQuery Clients Possible VOQL Architecture later sooner WebServices Participants VOQL Portal High Level Language allowing seemingly uniform access to services. Meta-data AreaQuery VOQLQuery Lower level QL (including AREA) and services to Support VOQL. Registry

3. Science Use Cases • It is important to collect science use cases to consider which functions are necessary to be implemented in the VOQL. • XMATCH, LINEMATCH, ,,,,

4. Definition of VOQL ? What is the definition of VOQL ?? Option A) VOQL expresses only what astronomers want to “OBSERVE” on VO(s). science cases →(VOQL)→ VO system Option B) VOQL is a protocol just to communicate between two VOs. Option C) VOQL is a general protocol to communicate inside VO system(s).

Possible Definition "A language for the exchange of astronomers' queries with the VO system, which allows expression of the science user scenarios, within reason, and output structured data. needs info on data model !!

5. Requirements for VOQL • Need to express scientific use cases to the maximum extent (not ALL !) • Extensible • Easy to learn (For averaged users GUIs are necessary. Advanced people may want to describe/ edit requests.) • Independent from metadata / registry

Further Discussion Continued on the net : voql@ivoa.net Join us !!

Progress Report of VOQL WG