Japanese Virtual Observatory (JVO) Prototype 2
Masahiro Tanaka, Yuji Shirasaki, Satoshi Honda, Yoshihiko Mizumoto, Masatoshi Ohishi (NAOJ), Naoki Yasuda(U. Tokyo), Yoshifumi Masunaga, (Ochanomizu U.), Yasuhide Ishihara, Katsumi Abe, Jumpei Tsutsumi (FujitsuLtd.), Hiroyuki Nakamoto, Yuusuke Kobayashi, Tokuo Yoshida, Yasuhiro Morita (SEC Ltd.)
URL: http://jvo.nao.ac.jp/ABSTRACT
We describe the architecture of the Japanese Virtual Observatory (JVO) prototype system version 2. JVO aims at seamless access to astronomical data archives stored in distributed data servers as well as
data analysis environment. For this purpose, it is important to build a framework for access to remote servers, including remote procedure calls (RPCs) and data transfer. A data request for distributed
database is written in the JVO Query Language. The JVO system parses the query language, decomposes it into individual remote procedures such as retrieval of catalog, image and spectrum and crossmatching, and generate a work flow. Based on this work flow, remote procedures are called. For RPCs of JVO prototype system 1, we employed Globus toolkit 2 (GTK2). However, latency time of GTK2
RPCs was too long for successive short-time jobs. Therefore, we employ Globus toolkit 3 (GTK3) for JVO prototype system 2. As the result, we find that Grid Service in GTK3 improves performance of RPC.
In addition to Grid Service, Reliable File Transfer (RFT) is used for efficient data transfer. Astronomical data stored in distributed servers are discovered through a registry server which provides metadata
discussed in the IVOA registry working group and is built using a XML database.

Configuration ofJVO Prototype 2

Development ofJVO Prototype 2

The main purpose of the JVO prototype is to test
functionality of JVOQL and employed technologies.
This description is based on JVO prototype version 2.

Query Interface

Result Display

You can choose catalogs andspecify query conditions on
WWW browser. Then JVOQL
sentence is automaticallygenerated.

You can browse search results (VOTable,FITS) on your WWW browser with varioustools (table viewer, three-color synthesis,color-color plot, etc).

Three-colorsynthesis

JVO developmentJVO Project start ― April 2002
Prototype 1 finish ― March 2003
Prototype 2 (this poster) finish ― March 2004
Prototype 3 ― under development

Data Discovery

Subaru SXDS catalog
and images•Proto1: UDDI
–UDDI is for “Service discovery”, not for “Data discovery”•Proto2: XMLDB–XMDB product “Karearea” is used.

SDSS QSO catalog
and spectra.

User–XPath search–enables both “Data discovery” and “Service discovery”–Metadata contents are based on IVOA standardController

JVO PortalComponents

User Interface•“JVOQL Parser” generates queryfor each host•“Scheduler” generates schedulebased on execution results•“Executer” executes services onremote hosts

Description of Workflow•Count queries can be executed inparallel.
•Search and XMatch service canbe called sequentially.
→ “Dependency” is considered.

Subaru
ALMA
SDSS
2MASS
...

Registry

Grid Service

is a facility to maintain and provide
metadata, i.e., information on remoteservers, services and observational
data archives. Metadata is expressedin XML form, and stored into XML DB.

Registry(XML DB)

Controller
JVOQL parser
Scheduler
ExecuterGrid Service
RFT, SFS

Users’ Storage

Performance of Grid ExecutionProto1:–Globus toolkit ver 2–globus-job-run command is used
–1 call = 30 sec — slow!
•1 query ~10 min!

Proto2:

Grid•Distributed servers of JVO are federated using Grid.
•Globus Toolkit ver.3 is employed as a Grid middleware.
•Grid Service is used for remote procedure calls.
•RFT (Reliable File Transfer) is used fordata transfer between data servers, andSFS (Self-certifying File System) for transfer
between server and portal.

Grid Service
RFT, SFS

Grid Service
RFT, SFS

Query&XMatchservice

Image&Spectrum
service

Data
Archives

Data
Archives

Data ServerSubaru, SDSS and 2MASS data are stored into distributed dataservers using RDB. Query services are implemented to handle
JVOQL-specific functions and output VOTable. XMatch service
and Image/Spectrum retrieval services are also implemented.
These services are called by Grid Service.

Grid Service
RFT, SFS

Data
AnalysisAnalysis Server
As an example of research using
JVO, We implemented a service
to search for gravitational lens
objects from Subaru data.

–Globus toolkit ver 3–using Grid Service–1 call = 2-3 sec — fast!
•overhead time is only ~ 30 ms

Data Transfer•We tried:–RFT (Reliable File Transfer; GridFTP)–GSI-SFS•We employed RFT–SFS is not flexible (A server cannot be a client).
•However,–Need support for HTTP and Web Services tointeroperate with IVOA.

Plans toward Prototype 3•support SIAP, SSAP, SkyNode•implement ADQL
•employing OAI-PMH architecture•flexible workflow architecture•introduce User management•etc.