Download VO-DAS

VO-DAS
Chenzhou CUI
Chao LIU, Haijun TIAN, Yang YANG, etc
National Astronomical Observatories, CAS
VO Data Access Service (VO-DAS)
 An OGSA-DAI based service system to provide unified access to
astronomy data, including catalogs, images and spectra.
 Goals of VO-DAS
 Supporting high volume data query
 Interlinking distributed and heterogeneous archives
• catalogs, images, spectrums
 Providing a software that works for astronomers
First Science Paper from China-VO
 Candidate Milky Way satellites in the Galactic halo（Liu et al., 2008,
A&A)
 SDSS DR5 photometric data were searched for new Milky Way
companions or substructures in the Galactic halo.
 Data analysis procedures were based on the VO-DAS.
 Five candidates are identified as over-dense faint stellar sources that
have color-magnitude diagrams similar to those of known globular
clusters, or dwarf spherical galaxies.
Predicted Features
 Goals: Uniform access to heterogeneous distributed datasets,
bulk of data support
 Functions









Catalog, image, and spectrum support
Dataset encapsulating and registry
Data discovery
Metadata description
Jointed query on heterogeneous databases
Bulk of data transfer support
Sync and async queries
Query status tracer
ADQL support
Architecture
 Components





VO-DAS server
DataNode
Clients
Registry
Data storage
Technical Highlights
OGSA-DAI based data node
Asynchronous query and cross match on
distributed databases
Extended ADQL, supporting catalog, image
and spectrum at the same time
Async Query
 Query segmented into subqueries
 Queries assigned to specific
DataNodes
 Query results transfer among
DataNodes
 Final results sent to data storage
service (VOSpace, FTP, etc)
 VO-DAS server supervises the
whole process
 No data exchange between
DataNode and VO-DAS server
Extended ADQL
SELECT s.ra, s.dec, s.g-s.i gi, s.i FROM
SDSSDR5:star s WHERE s.ra>=120 AND
s.ra<=270 AND s.dec>=25 AND s.dec<=70 AND
s.i>=19 AND s.i<=22 AND s.g-s.i>=0 AND s.gs.i<=1
SELECT f.Access_reference FROM
SDSSDR6:specfile f, SDSSDR6:sspParams s
WHERE s.specID=f.specID AND f.SNR>10 AND
s.alphafea<=0.2 AND s.feha>-0.9
VO-DAS Clients
 GUI
 CLI
 WebBrowser
 MATLAB Client
Interoperability
PLASTIC, SAMP
MATLAB based DM environments
VO Tools
(Aladin, TOPCAT)
Astrobox
MATLAB
VO-DAS Client
VO-DAS
MATLAB
Database Toolbox
Java
Libraries
VOTables
PLASTIC
Local
DB
AstroBox
VO Tools
(Aladin, TOPCAT)
PLASTIC
AstroBox
MATLAB
VO-DAS Client
VO-DAS
MATLAB
Database Toolbox
Java
Libraries
VOTables
 A plug-in package for MATLAB to
provide an astronomical data mining
application service, supporting VO
protocols and tools.
 A high-level data analysis
environment supporting:
 PLASTIC
 VOTable
 Local DB
 VO-DAS client
 Astronomical algorithms
Local
DB
MATLAB based DM environments (cont.)
Science case：
Sub-structure
study for the
Galaxy
Methodology
Density count in area (ra=120~270deg,
dec=25~70deg) where i=19~22 and g-i=0~1 in
the SDSS DR5 (bin=0.2x0.2deg)
Obtained 524 over density area
Calculate CMD for each area
Identify these CMDs by hands
Results
Work done by VO-DAS
 70 millions records queried from
SDSS DR7 database
 Calculate CMD for each over
density area
Other tasks done by MATLAB
Lessons learned
Grid and SOAP based Too complex to
data access solution
control
is feasible
Low performance
Current: RESTful TAP DAS
Collaboration Environment
CSCW(computer supported cooperative work)
e-Science
VO
LAMOST DBs
ObservationDB
Collaboration Enviroments
Data
Processing
Scientific WGs
SciDB (internal)
Project Scientists
Research
Projects
Papers
SciDB (public)
Public Users