sept. 2003nvo team meeting / victoria1 voql/adql/mydb for vo william omullane johns hopkins...
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Sept. 2003NVO Team Meeting / Victoria 1
VOQL/ADQL/MYDB for VO
William O’MullaneJohns Hopkins University
THE US NATIONAL VIRTUAL OBSERVATORY
Sept. 2003NVO Team Meeting / Victoria 2
Virtual Observatory Query Language Layers
VOQL3 SkyXQuery
VOQL2 SkyQL
VOQL1 WebServices
future XML-based query language.
SQL-like query language and federation system i.e. combination of SkyQuery , JVOQL and VO standards
Astronomical Data Query Language (ADQL) and VOTABLE to exchange information between machines
Sept. 2003NVO Team Meeting / Victoria 3
Architecture
Clients
VOQL PortalHigh Level Language allowing
seemingly uniform access to services.
VOQLQuery
IVOA SkyNodesLower level ADQL (including regions) and services to Support VOQL.
later End 2003
Tables
MetaData
PerformQuery
Columns
LEV1
Tables
MetaData
PerformQuery
Columns
LEV2
XMatch
Tables
MetaData
PerformQuery
Columns
LEV1
RegistryRegister
Tables
MetaData
PerformQuery
Columns
LEV4
XMatch
ExecPlan
Footprint
Tables
MetaData
PerformQuery
Columns
LEV3
XMatch
ExecPlan
Open SkyQuery PortalUses only Registry, Lev3 and Lev4 SkyNodes.
SkyQuerySkyQueryWebApp
May use Services at any level
SKYQL
ADQL
VOQL
ADQL
ADQL
Sept. 2003NVO Team Meeting / Victoria 4
SkyNode Levels
Feature LEV1–ADQL
LEV2 – XMATCH
LEV3- SKYNODE
LEV4- SKYNODEAdvanced
Optional
ADQL – circle X X X X
Xmatch X X X
Performance Query X X
Takes exec plan X X
Footprint – Region intersect
X
MYDB X
Authentication X
Sept. 2003NVO Team Meeting / Victoria 5
SkyQL and ADQL
• Same semantics different syntax• ADQL - parse tree easy for SkyNodes• SkyQL – textual easy for humans• ADQl Includes Rots regions,
Xmatch,math functions
• Simple parser working both ways(demo)ADQLtoSkyQL SkyQLtoADQL
Sept. 2003NVO Team Meeting / Victoria 6
MYDB – not in v0.4
• local space for data and results– Like astorgrid mysapce
• Requires on node– User Identification– Job tracking/monitoring– Asynchronous execution
• CasJobs does all of this (short demo)– http://skyservice.pha.jhu.edu/devel/casjobs
• Should we try to do this for OpenSkyQuery now?• What about across nodes…
Sept. 2003NVO Team Meeting / Victoria 7
MYDB across Nodes
• Need user identification across nodes– Centralize (not nice technically nor
politically)– How to integrate with exiting mysapce and
MYDB …
• Federate ! (IBM/MS Paper )– Authentication service on each node– User signs up anywhere or uses exisiting id– Accept userids issued by trusted nodes
• Authenticate userid with node it is supposed to be from
Sept. 2003NVO Team Meeting / Victoria 8
Security with federated Auth.
• How secure do we want this?• Should the userid be:
– an encrypted token – just a number
• Do we copy user info to each node so we can have integrity constarins in our db on USERID
Sept. 2003NVO Team Meeting / Victoria 9
MYVOSPACE
Next step is an integration serviceOne stop service
Sept. 2003NVO Team Meeting / Victoria 10
Current Issues for discussion
Since v0.3
Sept. 2003NVO Team Meeting / Victoria 11
Hardcore Levels
• Drop Lev3 Skynode • Require Footprint/Region intersect for
Skynodes.
• Personally – I think we will have nodes without and would rather have a name for them
Sept. 2003NVO Team Meeting / Victoria 12
Interface Issue
Currently PerformQuery returns VOTableVotable performQuery (ADQL query)
M.Hill would like a more general wrapper e.g.IVOAResult performQuery (ADQL query)
Here IVOAResult would be abstract or a wrapper containing VOTable or some pointer to a file.
Would also allow for putting other things in result (region densities Yasuda San has suggested).
Sept. 2003NVO Team Meeting / Victoria 13
Neighbours or XMatch
• Xmatch is a probabilistic matching returning all neighbours taking account of errors.
• B. Mann suggests we should use lowest common denominator which is Neighbors – this would return all objects within a certain distance of each other not using the errors.
Sept. 2003NVO Team Meeting / Victoria 14
Region Specification Issue
Have suggested Region,RefionUrl,RegionXml. Region would take simple strings like ‘Circle j200 810 34.2 0.1’
A.Rots has another suggestion for Region strings which is comprehensive Is this as complex as just using the XML …
Sept. 2003NVO Team Meeting / Victoria 15
A. Rots Region Strings
define CSys = (TimeFrame = (TimeScale='TT') and (TimeRefPosition='TELESCOPE')) and (SpaceFrame = (CoordFrame='ICRS') and (CoordRefPosition='TELESCOPE')) and (SpectralFrame = 'OBSERVATORY') and (CoordFlavor = 'SPHERICAL')define CArea = (TimeInterval = (StartTime=(ISOTime='2000-01-01')) and (StopTime=(ISOTime='2002-12-31'))) and (Region = (Circle = (Center='60.0d,30.0d') and +(Radius='10arcmin')) and (SpectraLinterval = (LoLimit='1GHz') and (HiLimit='2GHz'))define CSpec = (Time = (CoordResolution<='10s')) and (Pos2Vector = (CoordResolution<='10arcsec,10arcsec')) and (Spectrum = (CoordResolution<='50MHz'))
The query:select <SelectList> from <ResourceList> where <WhereClauses> and SearchLocation = (CoordSystem = $CSys and CoordArea = $CArea