11/27/2003IVOA Small Projects Meeting China-VO Data Access Service Based on OGSA Jian Sang National Astronomical Observatory of China Chinese Virtual Observatory

11/27/2003IVOA Small Projects Meeting Outline VO,Grid and OGSA Build the catalog data service Build the image mosaic service Faced technical difficulties

11/27/2003IVOA Small Projects Meeting The Increase Of Astronomical Data The number of pixels and the data double every year! The total area of astro telescopes in m**2 The total Gigapixels of CCDs.

11/27/2003IVOA Small Projects Meeting Challenges The quantity of data nearly amounts to PB. The data is distributed and stored in heterogeneous DBMSs in heterogeneous host environments.

11/27/2003IVOA Small Projects Meeting The VO’s Goal The VO’s initial goal is to federate existing astronomical data archives and provide standard services for manipulating these data. HOW TO REACH THIS GOAL ? The Grid technology can solve the problem!

11/27/2003IVOA Small Projects Meeting What is Grid Grid technology has been driven by genesis from metacomputing, but … In practice, the Grid is about resource sharing and coordinated problem solving in dynamic, multi-institutional virtual organizations Focus on how to enable, maintain and control the sharing of resources to achieve a common goal

11/27/2003IVOA Small Projects Meeting What “Grid“ offers:  Resource management protocols and services that support secure remote access to shared data resources and computing and the co-allocation of multiple resources.  Security solutions that support management of credentials and policies.  Information query protocols and services that provide configuration and status information about resources,organizations and services.  Data Management services that locate and transport datasets between storage systems and applications.

11/27/2003IVOA Small Projects Meeting What is OGSA The Open Grid Services Architecture (OGSA) represents an evolution towards a Grid system architecture based on Web services concepts and technologies. The OGSA integrates key Grid technologies (including the Globus Toolkit with Web services mechanisms to create a distributed system framework based around the Open Grid Services Infrastructure (OGSI). In Grids,Everything is Service

11/27/2003IVOA Small Projects Meeting The Open Grid Services Architecture Service orientation to virtualize resources From Web services:( everything is service) - Standard interface definition mechanisms:multiple protocol bindings,multiple implementations,local/remote transparency Building on Globus Toolkit: -Grid service :semantics for service interactions -Management of transient instances -Factory,Registry,Discovery,other services -Reliable and secure transport Multiple host environments:J2EE,.NET,C,…

11/27/2003IVOA Small Projects Meeting The Structure of Grid Service

11/27/2003IVOA Small Projects Meeting Grid service interfaces

11/27/2003IVOA Small Projects Meeting Construct The Astronomical Data Grid The astronomical data service is the most fundamental and important component in Virtual Observatory. In the aspect of data share, the VO can be think as a astronomical Data Grid VO=Astronomical Data Grid

11/27/2003IVOA Small Projects Meeting Outline VO,Grid and OGSA Build the catalog data access service Build the image mosaic service Faced difficulties

11/27/2003IVOA Small Projects Meeting The Classification of Astronomical Data Service Astronomical Catalog Service Image Mosaic Service Spectrum Data Service Simulation Data Service

11/27/2003IVOA Small Projects Meeting ClassDataSet NameData Amount （ zipped ） Catalog CDS/ADC Catalog sAbout 30G Other CatalogsAbout 120G Survey RealSky5G5G ROSAT X-ray Survey10G BATC360G DSS I60G DSS IIAbout 620G SDSS EDR30G SDSS DR1 (part)65G 2dF 2003 /2QZ7G Archive ROSAT X-ray Point28G Einstein X-ray Data5G Library ADS350G Total >1700GB Existing Astronomical Datasets we have

11/27/2003IVOA Small Projects Meeting Build Catalog Data Service How to federate the catalog data into VO,that is, how to build Data Service using the existing databases and programs?

11/27/2003IVOA Small Projects Meeting Define Catalog Service Interface Input Query Language : SQL(now),ADQL (plan) Output Data Format: VOTable 1.0 Catalog resource metadata registry protocol: VOResource 0.9 Some standards we used: input: ADQL query sentence output: VOTable format result it makes service interface/API simple.

11/27/2003IVOA Small Projects Meeting How to create a catalog data service that can understand ADQL and generate VOTable format result?? we adopt two ways! Reconstruct the existing catalog DBMS Encapsulate search program,like pmm The CDS has offered search program for big catalog like USNO A2,0….. How to use existing databases and programs to create catalog data service

11/27/2003IVOA Small Projects Meeting Catalog data service based on DB Catalog/metadata VOTable Wrapper ADQL/SQL Translator GT3 Interface ADQL VOTable JDBC SQLResultSet DBMS

11/27/2003IVOA Small Projects Meeting Advantage and disadvantage Can sufficiently use the functions of SQL language and implement complex query. DBMSs offer the most powerful functions for data management and maintenance. Need many works to reconstruct the DBs. To big catalogs, like USNOB1.0,2MASS PSC, query efficiency is low

11/27/2003IVOA Small Projects Meeting Data service based on search program VOTable Wrapper ADQL Translator GT3 Interface ADQLVOTable JNI/ stream program Data Files parameters

11/27/2003IVOA Small Projects Meeting Advantage and disadvantage Positional search is quicker than DB Only offer search functions that programs could offer. Many programs only offer position search functions,no statistical functions.

11/27/2003IVOA Small Projects Meeting Catalog Access Service Provided by us BandNameNum of objectsAmount X-rayRASS-BSC GB RASS-FSC GB optical USNO B GB USNO A GB GSC GB GSC GB UCAC >0.5 GB UCAC GB Tycho GB Hipparcos GB infrared2MASS PSC GB 2MASS ESC GB radioNVSS GB FIRST GB Total About 110 catalogs About 220GB

11/27/2003IVOA Small Projects Meeting How to call a Catalog data service Grid Client Resource Registry Data Service Factory Data Service Instance Create Data service Database

11/27/2003IVOA Small Projects Meeting Use Data Service to build www service for end user End Users Data service Services Register Services Register MySQL Oracle 9i Files Grid Client Web server Web Client Resources Register Resources Register http Data Mining Service Data processing Service Data Visualization Service End user don’t know where the data services are

11/27/2003IVOA Small Projects Meeting Use data service to create other service Our next work is to build a multi-wavelength cross-identification service (MWCI)based on the catalog data service. What is multi-wavelength cross-identification ? To cross-identify datasets by positional consistency, we can understand objects from different wavelength properties.

11/27/2003IVOA Small Projects Meeting The steps of multi-wavelength cross-identification Cross-identify datasets from different wavelengths within error radius. Divide the result of cross-identification into three situations: one-to-one, one-to-two, one- to-many. Choose the one-to-one entry for data mining The other two situations need statistical analysis to determine which source are the true counterpoint.

11/27/2003IVOA Small Projects Meeting Requirements Locate the datasets that users want to use. (dataset discovery) How to cross-match the datasets in heterogeneous DBMSs at different locations effectively and efficiently. Find storage resource to store the results

11/27/2003IVOA Small Projects Meeting User Application NVSS Storage Service Provider storage Factory MWCI Factory Registry Data Service 2MASS Data Service MWCI Service Provider storage MWCI

11/27/2003IVOA Small Projects Meeting Outline VO,Grid and OGSA Build the catalog data access service Build the image mosaic service Faced technical difficulties

11/27/2003IVOA Small Projects Meeting Build The Image Mosaic Service Use DSS-I sky image build our first image mosaic service.

11/27/2003IVOA Small Projects Meeting the definition of interface of service Input parameters: 1.RA,2.Dec,3.image height,4.image width transport protocols :gridFTP Output Data format :fits

11/27/2003IVOA Small Projects Meeting Realization of DSS-I image mosaic service GT3 Interface JNI/ Fits file GetImage parameters DSS-I Image Files GridFTP

11/27/2003IVOA Small Projects Meeting Outline VO,Grid and OGSA Build the catalog data access service Build the image mosaic service Faced technical difficulties

11/27/2003IVOA Small Projects Meeting Technical Difficulties service/resource registry and discovery! ADQL2SQL translator protocol shortcoming

11/27/2003IVOA Small Projects Meeting protocol shortcomings The shortcomings of VOTable 1.0 protocol 1.How to encapsulate result of join query!! 2.The standard to encapsulating spectrum data 3.the definition of FIELD element is not strict and uncompleted The shortcoming of UCD 1.Can’t express concrete meaning,such as “ERROR”,Error for what?? 2. incomplete, example:HTMID has no UCD Lack of standard for Unit

11/27/2003IVOA Small Projects Meeting Q & A ? Thank You

11/27/2003IVOA Small Projects Meeting Our provided catalogs in Catalog Service BandNameNum of objectsAmount X-rayRASS-BSC GB RASS-FSC GB optical USNO B GB USNO A GB GSC GB GSC GB UCAC >0.5 GB UCAC GB Tycho GB Hipparcos GB infrared2MASS PSC GB 2MASS ESC GB radioNVSS GB FIRST GB Total About 110 catalogs About 220GB

11/27/2003IVOA Small Projects Meeting The Step Of Calling A Data Service

11/27/2003IVOA Small Projects Meeting Transparencies for Astro Data Access Heterogeneity Transparency Name Transparency Distribution Transparency

11/27/2003IVOA Small Projects Meeting What is Grid Service?

11/27/2003IVOA Small Projects Meeting What Is The Data Grid DataGrid : A dynamic logical namespace that enables coordinated sharing of heterogeneous distributed storage resources and digital entities based on local and global policies across administrative domains in a virtual enterprise. DataGrid –Logical name space for location independent identifiers –Abstractions for storage repositories, information repositories, and access APIs –Latency management

11/27/2003IVOA Small Projects Meeting Data Grid Using a Data Grid – in Abstract Ask for data User asks for data from the data grid Data delivered The data is found and returned Where & how details are managed by data grid

11/27/2003IVOA Small Projects Meeting