slide1
Download
Skip this Video
Download Presentation
China-VO Data Access Service Based on OGSA

Loading in 2 Seconds...

play fullscreen
1 / 45

China-VO Data Access Service Based on OGSA - PowerPoint PPT Presentation


  • 80 Views
  • Uploaded on

Chinese Virtual Observatory. China-VO Data Access Service Based on OGSA. Jian Sang National Astronomical Observatory of China. Outline. VO,Grid and OGSA Build the catalog data service Build the image mosaic service Faced technical difficulties. The total area of astro telescopes in m**2.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' China-VO Data Access Service Based on OGSA' - saxton


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Chinese Virtual Observatory

China-VO Data Access Service

Based on OGSA

Jian Sang

National Astronomical Observatory of China

IVOA Small Projects Meeting 2003

outline
Outline
  • VO,Grid and OGSA
  • Build the catalog data service
  • Build the image mosaic service
  • Faced technical difficulties

IVOA Small Projects Meeting 2003

the increase of astronomical data

The total area of astro telescopes in m**2

The total Gigapixels of CCDs.

The number of pixels and the data double every year!

The Increase Of Astronomical Data

IVOA Small Projects Meeting 2003

challenges
Challenges
  • The quantity of data nearly amounts to PB.
  • The data is distributed and stored in heterogeneous DBMSs in heterogeneous

host environments.

IVOA Small Projects Meeting 2003

the vo s goal
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!

IVOA Small Projects Meeting 2003

what is grid
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

IVOA Small Projects Meeting 2003

what grid offers
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.

IVOA Small Projects Meeting 2003

what is ogsa
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

IVOA Small Projects Meeting 2003

the open grid services architecture
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,…

IVOA Small Projects Meeting 2003

the structure of grid service
The Structure of Grid Service

IVOA Small Projects Meeting 2003

grid service interfaces
Grid service interfaces

IVOA Small Projects Meeting 2003

construct the astronomical data grid
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

IVOA Small Projects Meeting 2003

outline1
Outline
  • VO,Grid and OGSA
  • Build the catalog data access service
  • Build the image mosaic service
  • Faced difficulties

IVOA Small Projects Meeting 2003

the classification of astronomical data service
The Classification of Astronomical Data Service
  • Astronomical Catalog Service
  • Image Mosaic Service
  • Spectrum Data Service
  • Simulation Data Service

IVOA Small Projects Meeting 2003

slide15

Existing Astronomical Datasets we have

IVOA Small Projects Meeting 2003

build catalog data service
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?

IVOA Small Projects Meeting 2003

define catalog service interface
Define Catalog Service Interface

Some standards we used:

  • Input Query Language : SQL(now),ADQL (plan)
  • Output Data Format: VOTable 1.0
  • Catalog resource metadata registry protocol:

VOResource 0.9

input: ADQL query sentence

output: VOTable format result

it makes service interface/API simple.

IVOA Small Projects Meeting 2003

how to use existing databases and programs to create catalog data service
How to use existing databases and programs to create catalog data service

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…..

IVOA Small Projects Meeting 2003

catalog data service based on db
Catalog data service based on DB

GT3 Interface

VOTable

ADQL

ADQL/SQL

Translator

VOTable

Wrapper

SQL

ResultSet

JDBC

Catalog/metadata

DBMS

IVOA Small Projects Meeting 2003

advantage and disadvantage
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

IVOA Small Projects Meeting 2003

data service based on search program
Data service based on search program

GT3 Interface

ADQL

VOTable

ADQL

Translator

VOTable

Wrapper

parameters

stream

JNI/

program

Data Files

IVOA Small Projects Meeting 2003

advantage and disadvantage1
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.

IVOA Small Projects Meeting 2003

catalog access service provided by us
Catalog Access Service Provided by us

IVOA Small Projects Meeting 2003

how to call a catalog data service
How to call a Catalog data service

Resource

Registry

1.<Find Factory>

<registry>

2.<Factory GSH>

3.<create data service>

Data

Service

Factory

Grid

Client

4.<Data service GSH>

Create

Data

service

5.<data request(ADQL)>

Data

Service

Instance

6.<result (VOTable)>

Database

IVOA Small Projects Meeting 2003

use data service to build www service for end user

End Users

Data service

Data service

Data service

Use Data Service to build www service for end user

Web Client

End user don’t know where the data services are

http

Data Mining

Service

Data Visualization

Service

Data processing

Service

Web server

Grid Client

Resources

Register

Services

Register

MySQL

Oracle 9i

Files

IVOA Small Projects Meeting 2003

use data service to create other service
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.

IVOA Small Projects Meeting 2003

the steps of multi wavelength cross identification
The steps of multi-wavelengthcross-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.

IVOA Small Projects Meeting 2003

requirements
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

IVOA Small Projects Meeting 2003

slide30

Registry

MWCI

Factory

Data

Service

2

4

2MASS

1

MWCI

5

MWCI Service Provider

User

Application

.

.

.

3

6

.

.

.

5

Data

Service

storage

Factory

7

6

NVSS

4

storage

Storage Service Provider

IVOA Small Projects Meeting 2003

outline2
Outline
  • VO,Grid and OGSA
  • Build the catalog data access service
  • Build the image mosaic service
  • Faced technical difficulties

IVOA Small Projects Meeting 2003

build the image mosaic service
Build The Image Mosaic Service
  • Use DSS-I sky image build our first image mosaic service.

IVOA Small Projects Meeting 2003

the definition of interface of service
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

IVOA Small Projects Meeting 2003

realization of dss i image mosaic service
Realization of DSS-I imagemosaic service

GridFTP

GT3 Interface

JNI/

Fits file

parameters

GetImage

DSS-I Image

Files

IVOA Small Projects Meeting 2003

outline3
Outline
  • VO,Grid and OGSA
  • Build the catalog data access service
  • Build the image mosaic service
  • Faced technical difficulties

IVOA Small Projects Meeting 2003

technical difficulties
Technical Difficulties
  • service/resource registry and discovery!
  • ADQL2SQL translator
  • protocol shortcoming

IVOA Small Projects Meeting 2003

protocol shortcomings
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

IVOA Small Projects Meeting 2003

slide38

Thank You

Q & A

?

www. .org

IVOA Small Projects Meeting 2003

our provided catalogs in catalog service
Our provided catalogs in Catalog Service

IVOA Small Projects Meeting 2003

the step of calling a data service
The Step Of Calling A Data Service

IVOA Small Projects Meeting 2003

transparencies for astro data access
Transparencies for Astro Data Access
  • Heterogeneity Transparency
  • Name Transparency
  • Distribution Transparency

IVOA Small Projects Meeting 2003

what is grid service
What is Grid Service?

IVOA Small Projects Meeting 2003

what is the data grid
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
    • Abstractionsfor storage repositories, information repositories, and access APIs
    • Latency management

IVOA Small Projects Meeting 2003

using a data grid in abstract

Data delivered

Ask for data

  • The data is found and returned
  • Where & how details are managed by data grid
Using a Data Grid –in Abstract

Data Grid

  • User asks for data from the data grid

IVOA Small Projects Meeting 2003

ad