1. IVOA RM, VOResources, Identifiers, Interfaces Chenzhou CUI

2. Agenda Why Registry? IVOA Resource Metadata 1.01 VOResource 0.10 IVOA Identifiers 1.1 IVOA Registry Interfaces 1.02

3. Semantic Web

4. Current Web Resources: identified by URI's untyped Links: href, src,... limited, non-descriptive User: Exciting world - semantics of the resource, however, gleaned from content Machine: Very little information available - significance of the links only evident from the context around the anchor.

5. Semantic Web Resources: Globally Identified by URI's or Locally scoped (Blank) Extensible Relational Links: Identified by URI's Extensible Relational User: Even more exciting world, richer user experience Machine: More processable information is available (Data Web) Computers and people: Work, learn and exchange knowledge effectively

6. Semantic Web 一种能让计算机理解的新型 Web 内容形 式 "The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation." -- Tim Berners-Lee, James Hendler, Ora Lassila, The Semantic Web, Scientific American, May 2001The Semantic Web

7. Metadata Metadata: data for data Dublin Core Metadata

8. The role of Resource Registries Used to discover and locate resources — data and services — that can be used in a VO application Resource: anything that is describable and identifiable. Besides data and services: organizations, projects, software, … Presently concerned with simple set of resource types Registry: a list of resource descriptions Expressed as structured metadata to enable automated processing and searching

9. An Overview of Data Discovery You can search the main VO registries to find resources based on descriptive criteria NVO Registries are “ coarse-grained ” You can find organizations, archives, catalogs Won ’ t find images, celestial objects, table records AstroGrid Registries are “ fine-grained ” Table columns, individual images and associated metadata Registry framework contains multiple registries: searchable registries publishing registries

10. Local Publishing Registry Local Searchable Registry Full Searchable Registry Local Publishing Registry Full Searchable Registry Data Centers VO Projects Specialized Portals & Services Registry Framework

11. Local Publishing Registry Local Searchable Registry Full Searchable Registry Local Publishing Registry Full Searchable Registry Data Centers VO Projects Specialized Portals & Services Registry Framework harvest (pull)

12. Local Publishing Registry Local Searchable Registry Full Searchable Registry Local Publishing Registry Full Searchable Registry Data Centers VO Projects Specialized Portals & Services Registry Framework harvest (pull) replicate

13. Local Publishing Registry Local Searchable Registry Full Searchable Registry Local Publishing Registry Full Searchable Registry Data Centers VO Projects Specialized Portals & Services Registry Framework harvest (pull) replicate selective harvesting

14. Local Publishing Registry Local Searchable Registry Full Searchable Registry Local Publishing Registry Full Searchable Registry Data Centers VO Projects Specialized Portals & Services Client Applications search queries Registry Framework

15. Local Publishing Registry Local Searchable Registry Full Searchable Registry Local Publishing Registry Full Searchable Registry Data Centers VO Projects Specialized Portals & Services Client Applications search queries Registry Framework

16. Overview of Publishing Resources are published if one can use VO facilities to find them. Multiple layers of publishing Starts with registry description of resource Data Access Services Incremental exposure for incremental effort Who are you? How you publish depends on what you want to publish. An individual with a small data collection An archive center Someone with a cool service

17. Persistent Archives:Tools for Federation Registering your resources with a VO publishing registry Enter description into registration form at one of the available NVO registries: STScI/JHU Registry: http://nvo.stsci.edu/voregistry/http://nvo.stsci.edu/voregistry/ NCSA Registration Portal: http://nvo.ncsa.uiuc.edu/nvoregistration.html http://nvo.ncsa.uiuc.edu/nvoregistration.html Caltech Carnivore: http://mercury.cacr.caltech.edu:8080/carnivore/ http://mercury.cacr.caltech.edu:8080/carnivore/ If you have a large number of resources to register, you can run your own registry on your own site NCSA VORegistry-in-a-Box http://nvo.ncsa.uiuc.edu/VO/software/ http://nvo.ncsa.uiuc.edu/VO/software/ Caltech Carnivore: http://mercury.cacr.caltech.edu:8080/carnivore/ http://mercury.cacr.caltech.edu:8080/carnivore/

18. What can/should you register? Should: your Organization Declares yourself as a publisher with an ID Should: your Collection Can: your existing services Browser-based services: e.g. search page Traditional CGI services Web Services The next level … Implement and register one or more standard services Cone Search Simple Image Access SkyNode* Simple Spectral Access* *standard still in development Persistent Archives:Tools for Federation

19. Resource Metadata: XML Schema Classes of Resources Organisation, DataCollection, Service, Registry Specific classes inherit from generic Organized into separate schemas: Core resource metadata: VOResource Various extensions schemas containing specific types Capable of describing … Data centers, research organizations, missions, observatories Data collections, archives VO standard services: Cone Search, Simple Image Access Existing Browser/CGI-based services Web Services

20. Describing Resources with XML:VOResource Model: types of Resources Generic Resource Extensions: e.g. DataCollection, Service, ConeSearch, … VOResource: Family of XML schemas Core schema: VOResource Common set of metadata applicable to all resources including Dublin Core Resource types: Resource, Service, Organisation Extension schemas to describe specific kinds of resources Extended type inherits generic metadata adds metadata specific to the type of resource Extensibility allows for evolution Developers only need to support types of interest to them Allows developers to experiment with non-standard extensions Currently transitioning from v0.9 to v0.10 Lastest status of metadata standards: http://www.ivoa.net/twiki/bin/view/IVOA/ResourceMetadata

21. Extension Schemas VODataService: describing data and services Types: DataCollection, SkyService, TabularSkyService ConeSearch: describes location and behavior of a Cone Search service Types: ConeSearch SIA: describes location and behavior of a Simple Image Access service Types: SimpleImageAccess VORegistry: metadata for managing registries Types: Registry, Authority

22. IVOA Identifiers Two formats String XML Two components Authority ID Resource Key

23. A word about Identifiers … IVOA Identifier: a globally-unique URI identifying a resource Ex: ivo://adil.ncsa/targeted/SIA Required as part of a registered resource description As publisher, you control what it looks like Two components: Authority ID: e.g. adil.ncsa, hst.nasa, vlt.eso Defines a namespace for identifiers Owned by a single publishing organization Resource Key: e.g. targeted/SIA, acs/SIA Name for the resource unique within the namespace Encourage re-use of local identifiers

24. IVOA Standard Registry Interface IVOA Working Draft: 2 parts Harvesting: sending descriptions from publishers to searchable registry Searching methods keywordSearch(string words, boolean combineByOr) search(ADQLWhere constaints) Returns a list of VOResource descriptions Advanced searching with ADQL: Just the “ where ” part — i.e. search constraints--of ADQL In place of column names, use XPath to VOResource element Curation/Publisher like ‘ %NASA% ’ Query extensible to any VOResource XML extension Maps readily to registry implementations based on RDBMS or XML-DB.

25. Registry Interfaces Search KeywordSearch GetResigistries Harvesting Identify ListIdentifiers ListRecords GetRecords ListMetadataFormats ListSets

26. Why might a client use the standard search interface? Uniform interface to all VO Registries Not dependent on a single registry Direct relationship between information you are querying and information you get back. Extensible to any type of resource description Re-use of ADQL Custom interfaces to Registries: Registries can provide extended functionality More advanced capabilities: e.g. XQuery Simpler interfaces for specialized purposes Client toolkits can provide simplifying interfaces Support for ADQL/s XPath aliases

27. The Registry standard addresses the need for an astronomer to be able to locate, get details of, and make use of, any resource located anywhere in the IVO space, ie in any Virtual Observatory.

28. IVOA Registry Definition: The IVOA Registry will allow an astronomer to be able to locate, get details of, and make use of, any resource located anywhere in the IVO space, ie in any Virtual Observatory. The IVOA will define the protocols and standards whereby different registry services are able to interoperate and thereby realise this goal.

29. IVOA Resource Registry Specifications

30. OAI links Open Archives Initiative Protocol for Metadata Harvesting (2.0) OAI - Repository Explorer( 检测接口与 OAI 的兼容性） OAI Tools Registry Interface Registry Interface, HarvestingIssuesHarvestingIssues