Aus-VO Workshop 2003 International Virtual Observatory Alliance effort on Virtual Observatory Query Language Naoki Yasuda (JVO), VOQL WG

Aus-VO Workshop 2003 VOQL Working Group Chair : Masatoshi Ohishi (JVO) William O'Mullane, Tamas Budavari, Vivek Haridas, Nolan Li, Tanu Malik, Alex Szalay (NVO, JHU) Martin Hill, Tony Linde, Bob Mann, Clive Page (AstroGrid) Jim Gray (Microsoft) Yoshihiko Mizumoto, Naoki Yasuda (JVO) have contributed.

Aus-VO Workshop 2003 Brief History Jan 2003 at Seattle : First IVOA Meeting Start WG May 2003 at Cambridge : IVOA Interoperability Meeting Agreed on ADQL and SkyNode concept Jul 2003 : First Working Draft Discussions on mailing list have been continued. Oct 2003 at Strasbourg : IVOA Interoperability Meeting More detailed discussion Nov 2003 : Version 0.6 Working Draft is available

Aus-VO Workshop 2003 Architecture

Aus-VO Workshop 2003 Architecture Description Astronomical Data Query Language (ADQL) is an SQL like language but passed as an XML document. SkyNodes have standard interface and will accept ADQL and return the query result as VOTable. SkyQL have the same semantics as ADQL but the syntax would be an SQL like string rather than XML. VOQL is an ambitious language at a higher level than ADQL.

Aus-VO Workshop Layers of VOQL

Aus-VO Workshop 2003 ADQL and SkyQL Many astronomical data are tabular data and they are stored in relational database. SQL as a first step The only SQL command allowed in ADQL is aselect. Additional predicates are Region and XMatch. XMatch is supported in Full SkyNode. See the XSD for complete structure of ADQL.

Aus-VO Workshop 2003 Select t.*, b.* From Tab t, Bob b Where t.g <> b.g and Region('Circle J ') t b Tab t Bob b t g <> b g Ra Dec SkyQL vs ADQL We need SkyQL as a human readable expression.

Aus-VO Workshop 2003 SkyNode All data servers joining the IVO would implement a standard IVOA SkyNode Interface based on Web Services. All VO WebServices shall implement theMetaData port. All VO WebServices shall implement theHeartbeat port.

Aus-VO Workshop 2003 Basic / Full SkyNode FeatureBasic SkyNodeFull SkyNodeOptional ADQL – circleXX FunctionsXX XMatchX QueryCostX Takes exec planX Footprint – Region intersectX MYDBX Authentication – must have with MYDB X

Aus-VO Workshop 2003 Basic SkyNode Interface //Return RSM compliant VOResource public VOResource MetaData(); //Return a list of all tables that may be used from this node. public string[] Tables(); //Return ucd, name, unit, type for each column of table public MetaColumn[] Columns(string table); //Return available query result formats, VOTable, DataSet, ASCII public string[] Formats(); //Return available functions public MetaFunctions[] Functions(); //Return the result of executing ADQL query in requested format public VOResult PerformQuery(Select query, string format);

Aus-VO Workshop 2003 Full SkyNode Interface //Returns object density per square degree for a given criteria. public float QueryCost(Select query); //Return Cross matched objects according to Query and input Tables public VOResult XMatch(Select select, VOTABLE[] votables); // Return result of executing an ExecPlan, format specified in plan public VOResult ExecutePlan(ExecPlan plan); //Return region of intersection between given region and this SkyNode public Region Footprint(Region region);

Aus-VO Workshop 2003 Open SkyQuery Portal Portal should not be in this specification, but some description will help how to use SkyNodes. Open SkyQuery Portal will enable the following query select s.ra, s.dec, s.r, s.i, s.g, s.objid, p.* from SDSS:PhotoObj s, Twomass:Photo t,First:Photo f, SDSS:Spectro p, IVOA:MyDB.MyObjList m where XMatch (s,t,f,m) < 3 and Region(Circle Cartesian ) and s.objid=p.objid and s.r<15 and abs(s.i-t.j_m)<2 Open SkyQuery Portal is open version of SkyQuery developed at JHU based on Microsoft.NET technology. Currently Open SkyQuery Portal will use only Full SkyNodes.

Aus-VO Workshop 2003 Discussions How to use Unified Content Descriptors? UCDs will hide raw column names. UCDs are not unique. XMatch algorisms? User customized XMatch. XMatch vs Neighboring Search Someone need all possible corresponding objects.

Aus-VO Workshop 2003 Summary ADQL and SkyNode architecture is adopted in VOQL WG. ADQL is SQL like language. SkyNode is WebService interface. Specifications of ADQL and SkyNode are almost finalized (Jan 2004). Full XML-baed VOQL (SkyXQuery) will be available in a few years. See details on