Virtual Observatory --Architecture and Specifications

Virtual Observatory--Architecture and Specifications

Chenzhou CuiChinese Virtual Observatory (China-VO)

National Astronomical Observatory of China

Contents

• Virtual Observatory (VO) Introduction• IVOA Architecture• IVOA Technical Specifications• IVOA In Action

Virtual Observatory (VO)• Virtual Observatory (VO) is a data-intensively online astronomical

research and education environment, taking advantages of advanced information technologies to achieve seamless, global access to astronomical information. – 虚拟天文台是通过先进的信息技术将全球范围内的研究资源无缝透明连接在一

起形成的数据密集型网络化天文研究与科普教育平台。 • The Virtual Observatory (VO) aims to provide a research environment

that will open up new possibilities for scientific research based on data discovery, efficient data access, and interoperability.

• International Virtual Observatory Alliance

--"facilitate the international coordination and collaboration necessary for the development and deployment of the tools, systems and organizational structures necessary to enable the international utilization of astronomical archives as an integrated and interoperating virtual observatory."

What is VO

The vision is of global astronomy archives connected via the VO to form a multi-wavelength digital sky that can be searched, visualized, and analyzed in new and innovative ways.

IVOA Architecture Level 0

• Astronomy produces large amounts of data of many kinds, coming from various sources: science space missions, ground based telescopes, theoretical models, compilation of results, etc. These data are usually managed by large data centres or smaller teams. These providers provide the scientific community with data and / or computing services through the Internet. This is the Resource Layer.

IVOA Architecture Level 0

• The “consumers” of these data and computing services, be it individual researchers, research teams or computer systems, interact with the User Layer.

• The Virtual Observatory is the necessary “middle layer” framework connecting the Resource Layer to the User Layer in a seamless and transparent manner.

IVOA Architecture Level 0

• The VO provides a technical framework for the providers to share their data and services (“Sharing”), and allowing users to find (“Finding”) these resources, to get them (“Getting”) and to use them (“Using”). To enable these functionalities, the definition of some core astronomically-oriented standards (“VO Core”) is also necessary.

IVOA Architecture Level 1

• Level 1 of the IVOA architecture is an extension to the Level 0, displaying more details about the functionalities and building blocks within the different layers.

• The Resource Layer can be:• data collections• storage services• computing services

IVOA Architecture Level 1

• Interactions between Resource Layer and User Layer can be through browser based applications in a typical web browser, standalone desktop applications or scriptable applications that can be used in automatic and batch modes by a computer.

• The Virtual Observatory is the necessary “middle layer” framework which connects the Resource Layer to the User Layer in a seamless and transparent manner. The VO provides a technical framework for the providers and the consumers to share their data and services (“Sharing”).

IVOA Architecture Level 1

• Registries function as the “yellow pages” of the VO, collecting metadata about data resources and information services into a queryable database.

• Access to data and metadata collection is done through Data Access Protocols, which specify a uniform way of getting data and metadata from various different providers.

IVOA Architecture Level 1• To allow these functionalities, the definition of some core astronomically-oriented

standards (“VO Core”) is necessary. In particular, defining common formats and data models and using common semantics is required to have a uniform and common description of astronomical datasets so they can become interoperable and queryable through standard query languages to enable cross analysis amongst various datasets.

• Additional standards are required within the User Layer to enable user authentication to proprietary datasets and storage elements as well as interoperability amongst VO applications (“Using”).

IVOA Architecture Level 2

Document Standards Management

Apps Applications WG

DAL Data Access Layer WG

DaM Data Modeling WG

GWS Grid & Web Services WG

ReR Resource Registry WG

Semantics Semantics WG

SDP Standards & Documents Process WG

VOE VO Event WG

VOT VOTable WG

VQL VO Query Language WG

Resource Registration

Data Models

Semantics

Grid and Web Services

Data Access

Application and Messaging

Finding & Getting

In Action – Observation Publishing

In Action – Image Publishing

In Action – TOPCAT Catalog Access

Thank You!