Astronomical Data Analysis Software and Systems XV
ASP Conference Series, Vol. XXX, 2005
C. Gabriel, C. Arviset, D. Ponz and E. Solano, eds.

O7.9

Development of Japanese Virtual Observatory (JVO) :Experience on Interoperation with other Virtual
Observatories and its Future Plan
Masatoshi Ohishi, Yuji Shirasaki, Masahiro Tanaka, Satoshi Honda,
Satoshi Kawanomoto, & Yoshihiko Mizumoto
National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka,Tokyo, 181-8588 Japan
Naoki Yasuda
University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa, Chiba, 277-8582
JapanYoshifumi Masunaga
Ochanomizu Univerisity, 2-1-1 Otsuka, Bunkyo-ku, Tokyo, 112-8610
JapanYasuhide Ishihara, & Jumpei Tsutsumi
Fujitsu Ltd., 1-9-3, Nakase, Mihama, Chiba 261-8588, Japan
Hiroyuki Nakamoto, & Yuusuke Kobayashi
Systems Engineering Consultants Co. Ltd., 22-4 Sakuraoka-cho,Shibuya-ku, Tokyo, 150-0031 Japan
Abstract.
Virtual Observatries (VOs) are emerging research environment forastronomy, and 16 countries and regions have funded to develop theirVOs based on international standard protocols for interoperability. National Astronomical Observatory of Japan (NAOJ) started its VO project(Japanese Virtual Observatory — JVO) in 2002, and developed its prototypes. We have succeeded to interoperate the latest JVO prototype
system with VOs in the USA and Europe since December 2004. Someobserved data by the Subaru telescope, ASCA satellite operated by theJAXA/ISAS, etc. are connected to the prototype. Successful interoperation of the JVO prototype with other VOs means that astronomers in theworld will be able to utilize top-level data obtained by these telescopesfrom anywhere in the world at anytime.
System design of the JVO system, experiences during our development including problems of current standard protocols defined in theIVOA, and proposals to resolve these problems in the near future aredescribed.

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1.

Ohishi et al.
Introduction

The National Astronomical Observatory of Japan (NAOJ) operates the Subaru
telescope in Hawaii and large radio telescopes in Nobeyama. All the observed
data are digitally archived and are accessible via internet. The radio telescopes ofNobeyama produce about 1 TBytes per year, and the Subaru telescope outputs
about 20 TBytes per year. NAOJ has joined the international project, ALMA,
and it is foreseen that more than a few PBytes of data per year will be produced
for the astronomy community.
Because astronomical objects radiate electromagnetic waves in wide frequency range, it has been recognized that multi-wavelength analyses are essential to understand physical and chemical behavior of galaxies, stars, planets andso on. The idea of the Virtual Observatory (VO) has recently appeared to resolve such situation, and the system has been developed in 16 countries andregion around the world. These individual VO projects set up an alliance, theInternational Virtual Observatory Alliance (IVOA1 ), to standardize protocols
for their interoperations.
JVO is designed to seamlessly access to multi-wavelength, federated databases
and data analyses systems for astronomers through high speed network facility. The basic concept and a new query language to access to the distributed
databases, JVO Query Language, are described in Ohishi et al. (2003).
Our past prototypes were not connected to other VOs, and it was desired toconnect with other VO prototypes. Thus we have incorporated several standards
that were developed in the IVOA, and have succeede to interoperate between
VOs in the US/Europe and JVO. This paper describes its implementation andassessment of the performance.
2.

Architecture of the Interoperable JVO system

Schematic diagram of the JVO system is shown in Figure 1. Its fundamental
design is similar to our previous prototype systems (Ohishi et al. 2003; Shirasaki
et al. 2004; Tanaka et al. 2004). Major diﬀerences are, e.g., adoption of theWeb Services instead of the Grid Services, adoption of standardized protocols
for the VOs (SIAP for images, SSAP for spectra, and ADQL for catalogs), andintroduction of resource meta data exchange mechanism based on the OAI-PMH.
Queries issued by a user are sent from the user terminal to the JVO portal, and are parsed into single queries to appropriate servers that are foundby consulting the registry. The parsed querying processes are executed by thescheduler, being passed to individual servers through appropriate protocol. The
query results are sent back with the VOTable format.
Major database servers connected to this prototype are SuprimeCAM from
Subaru telescope, ASCA (X-ray satellite) database operated by the Institute ofSpace and Astrocautical Science, Japan Aerospace Exploration Agency (JAXA/ISAS), and others. We succeeded to interoperate the JVO prototype with VOs
in the North America (NVO, VO-Canada) and Europe (ESO, ESAC, Astro1

http://www.ivoa.net/

Development of Interoperable JVO System

Figure 1.

3

Architecture of Interoperable JVO system.

grid2, CDS) in December 2004, and more than 110 astronomical resoureces areavailable as of Ocotober 2005.
The protocols to access images, spectra and catalogs have been developled
separately. Therefore it is necessary to prepare separate query interface to access to each resource. Astronomical researches may sometimes utilize images,spactra and catalogs simultaneously, and it is desirable to use an integrated
query interface to make such queries easier. Shirasaki et al. (2004) proposedsuch an integrated query language by using the ”virtual column” concept. We
implemented the integrated query language interface to the interoperable JVO
prototype, and succeeded to retrieve images/spectra/catalogs though a singleinterface. Further details are described in Shirasaki et al. (2005) in this volume.

3.

Measurement of Access TimeWe measured elapsed time to access data servers in the US. Table 1 summarizes”best” values obtained during our measurement. The elapsed times in our first
prototype was around several tens of seconds to access database servers ”within”
our prototype system (Ohishi et al (2003). This was because previous prototype
used the globus tool kit (GTK), and because a component in the globus tool kit
had a fixed waiting time of 30 seconds. Since the GTK was designed to makecollaborations for CPU-intensive jobs possible, we found the Web Services are
more suitable for data-intensive jobs with less CPU times. This is clearly shownin Table 1 where elapsed times for queries to the US are less than 10 seconds.
With such small elapsed times it would be possible for a user to interact with
the VO systems to search for suitable data for her/his researchs.

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Ohishi et al.

Table 1.

Sample Elapsed Time for Databases in the US.

bandSurvey Name

X-ray
InfraredRadio

Chandra
2MASS
VLA4.

Servercda.harvard.edu
mercury.cacr.caltech.edu
adil.ncsa.uiuc.edu

Time (second)
1.715
3.536
7.115

Future Plan

Now it was established to access data servers via VO interfaces. Thus it isnesessary for astronomical researches to analyze obtained data on the VO environment. We have been designing a work flow language to access remotely
located analysis engines. The work flow language will enable users not only
data queries but data analyses through a single user interface. The details aredescribed in a separate paper (Tanaka et al. 2005) in this volume. We plan toopen to some volunteers to use and to evaluate the JVO system by March 2006.
Then we plan to implement Single-Sign-On mechanism for secure user access, and other standardized interfaces by the IVOA, and to disseminate standard VO interfaces to astronomy communities not only in Japan but in (East)
Asian countries to further promote international collaborations. Such activity
is crucial for the ALMA era that we expect to produce more than a few Peta
Bytes per year.

Acknowledgments. This work was supported by the JSPS Core-to-Core
Program and Grant-in-aid“ Information Science ”(15017289 and 16016292) carried out by the Ministry of Education, Culture, Sports, Science and Technologyof Japan.
References
Ohishi, M. et al. 2003, in ASP Conf. Ser., Vol. 314, ADASS XII, ed. F. Ochsenbein, M. Allen, & D. Egret (San Francisco: ASP), [P3-11]
Shirasaki, Y. et al. 2004, will be given at a later time, [P1.1.23]
Shirasaki, Y. et al. 2005, this volume, [P.105]
Tanaka, M. et al. 2004, will be given at a later time, [P.1.1.24]
Tanaka, M. et al. 2005, this volume, [P.107]