一种能让计算机理解的新型Web内容形式

1、IVOA RM, VOResources, Identifiers, InterfacesChenzhou CUIAgendaWhy Registry?IVOA Resource Metadata 1.01VOResource 0.10IVOA Identifiers 1.1IVOA Registry Interfaces 1.02Semantic WebCurrent WebResources: identified by URIs untyped Links: href, src, . limited, non-descriptive User: Exciting world - sema

2、ntics of the resource, however, gleaned from content Machine: Very little information available - significance of the links only evident from the context around the anchor. Semantic WebResources: Globally Identified by URIs or Locally scoped (Blank) Extensible Relational Links: Identified by URIs Ex

3、tensible 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 Semantic Web一种能让计算机理解的新型一种能让计算机理解的新型Web内容形内容形式式 The Semantic Web is an extension of the curren

4、t 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 2001 MetadataMetadata: data for dataDublin Core MetadataThe role of Resource RegistriesUsed

5、 to discover and locate resourcesdata and servicesthat can be used in a VO applicationResource: anything that is describable and identifiable.Besides data and services: organizations, projects, software, Presently concerned with simple set of resource typesRegistry: a list of resource descriptionsEx

6、pressed as structured metadata to enable automated processing and searchingAn Overview of Data DiscoveryYou can search the main VO registries to find resources based on descriptive criteriaNVO Registries are “coarse-grained”You can find organizations, archives, catalogsWont find images, celestial ob

7、jects, table recordsAstroGrid Registries are “fine-grained”Table columns, individual images and associated metadataRegistry framework contains multiple registries:searchable registriespublishing registriesLocal PublishingRegistryLocal SearchableRegistryFullSearchableRegistryLocal PublishingRegistryF

8、ullSearchableRegistryDataDataCentersCentersVOVOProjectsProjectsSpecializedSpecializedPortals & ServicesPortals & ServicesRegistry FrameworkLocal PublishingRegistryLocal SearchableRegistryFullSearchableRegistryLocal PublishingRegistryFullSearchableRegistryDataDataCentersCentersVOVOProjectsPro

9、jectsSpecializedSpecializedPortals & ServicesPortals & ServicesRegistry Frameworkharvest(pull)Local PublishingRegistryLocal SearchableRegistryFullSearchableRegistryLocal PublishingRegistryFullSearchableRegistryDataDataCentersCentersVOVOProjectsProjectsSpecializedSpecializedPortals & Serv

10、icesPortals & ServicesRegistry Frameworkharvest(pull)replicateLocal PublishingRegistryLocal SearchableRegistryFullSearchableRegistryLocal PublishingRegistryFullSearchableRegistryDataDataCentersCentersVOVOProjectsProjectsSpecializedSpecializedPortals & ServicesPortals & ServicesRegistry F

11、rameworkharvest(pull)replicateselectiveharvestingLocal PublishingRegistryLocal SearchableRegistryFullSearchableRegistryLocal PublishingRegistryFullSearchableRegistryDataDataCentersCentersVOVOProjectsProjectsSpecializedSpecializedPortals & ServicesPortals & ServicesClientClientApplicationsApp

12、licationssearchqueriesRegistry FrameworkLocal PublishingRegistryLocal SearchableRegistryFullSearchableRegistryLocal PublishingRegistryFullSearchableRegistryDataDataCentersCentersVOVOProjectsProjectsSpecializedSpecializedPortals & ServicesPortals & ServicesClientClientApplicationsApplications

13、searchqueriesRegistry FrameworkOverview of PublishingResources are published if one can use VO facilities to find them.Multiple layers of publishingStarts with registry description of resourceData Access ServicesIncremental exposure for incremental effortWho are you? How you publish depends on what

14、you want to publish.An individual with a small data collectionAn archive centerSomeone with a cool servicePersistent Archives:Tools for FederationRegistering your resources with a VO publishing registryEnter description into registration form at one of the available NVO registries:STScI/JHU Registry

15、: /voregistry/NCSA Registration Portal: /nvoregistration.htmlCaltech Carnivore: :8080/carnivore/If you have a large number of resources to register, you can run your own registry on your own siteNCSA VORegistry-in-a-Box http:/nv

16、/VO/software/Caltech Carnivore: :8080/carnivore/What can/should you register?Should: your OrganizationDeclares yourself as a publisher with an IDShould: your CollectionCan: your existing servicesBrowser-based services: e.g. search pageTraditional CGI serv

17、icesWeb ServicesThe next levelImplement and register one or more standard servicesCone SearchSimple Image AccessSkyNode*Simple Spectral Access*standard still in developmentPersistent Archives:Tools for FederationResource Metadata: XML SchemaClasses of ResourcesOrganisation, DataCollection, Service,

18、RegistrySpecific classes inherit from generic Organized into separate schemas:Core resource metadata: VOResourceVarious extensions schemas containing specific typesCapable of describingData centers, research organizations, missions, observatoriesData collections, archives VO standard services: Cone

19、Search, Simple Image AccessExisting Browser/CGI-based servicesWeb ServicesDescribing Resources with XML:VOResourceModel: types of ResourcesGeneric ResourceExtensions: e.g. DataCollection, Service, ConeSearch, VOResource: Family of XML schemasCore schema: VOResourceCommon set of metadata applicable t

20、o all resources including Dublin CoreResource types: Resource, Service, OrganisationExtension schemas to describe specific kinds of resourcesExtended type inherits generic metadataadds metadata specific to the type of resourceExtensibility allows for evolutionDevelopers only need to support types of

21、 interest to themAllows developers to experiment with non-standard extensionsCurrently transitioning from v0.9 to v0.10Lastest status of metadata standards:http:/ Extension SchemasVODataService: describing data and servicesTypes: DataCollection, SkyService, TabularSkyServiceConeSearch: describes loc

22、ation and behavior of a Cone Search serviceTypes: ConeSearchSIA: describes location and behavior of a Simple Image Access serviceTypes: SimpleImageAccessVORegistry: metadata for managing registriesTypes: Registry, AuthorityIVOA IdentifiersTwo formatsStringXMLTwo componentsAuthority IDResource KeyA w

23、ord about IdentifiersIVOA Identifier: a globally-unique URI identifying a resourceEx: ivo:/adil.ncsa/targeted/SIARequired as part of a registered resource descriptionAs publisher, you control what it looks likeTwo components:Authority ID: e.g. adil.ncsa, hst.nasa, vlt.esoDefines a namespace for iden

24、tifiersOwned by a single publishing organizationResource Key: e.g. targeted/SIA, acs/SIAName for the resource unique within the namespaceEncourage re-use of local identifiersIVOA Standard Registry InterfaceIVOA Working Draft: 2 partsHarvesting: sending descriptions from publishers to searchable regi

25、strySearchingSearchingmethods keywordSearch(string words, boolean combineByOr)search(ADQLWhere constaints)Returns a list of VOResource descriptionsAdvanced searching with ADQL:Just the “where” parti.e. search constraints-of ADQLIn place of column names, use XPath to VOResource elementCuration/Publis

26、her like %NASA%Query extensible to any VOResource XML extensionMaps readily to registry implementations based on RDBMS or XML-DB.Registry InterfacesSearchSearchKeywordSearchGetResigistriesHarvestingIdentifyListIdentifiersListRecordsGetRecordsListMetadataFormatsListSetsWhy might a client use the stan

27、dard search interface?Uniform interface to all VO RegistriesNot dependent on a single registryDirect relationship between information you are querying and information you get back.Extensible to any type of resource descriptionRe-use of ADQLCustom interfaces to Registries:Registries can provide extended functio