The Resource Catalog (aka ResCat) service provides scalable registration and location of public resources available in the LEAD space, along with the metadata describing them. Resources include data products, individual files and collections (DataCatalog part of ResCat) and web-services (ServiceCatalog part of ResCat), but can be generalized to any network reference-able entity with metadata. The metadata is resource specific: a variation of FGDC, called the LEAD Metadata Schema, is used for data products; WSDL, Service Maps, Host maps, etc. are used for web-service resources. A web-service API is provided to manage the resource registrations (add, update, delete) and querying for them based on their metadata. The catalog is primarily populated by crawling known THREDDS catalogs, publishing collection from myLEAD, and by web-services being registered. It can be used to select services when composing workflows, locate service maps for creating services thro' the application factory, searching for input data products for workflows, etc.
The Resource Catalog is derived from the deprecated VO Catalog project that was part of the GSX toolkit. The VO Catalog was an implementation of the OGSI Grid Service Registration portType and was used to register Grid services and data products as OGSI ServiceGroupEntries. The resource catalog sheds the conformance to the now deprecated OGSI specification and is designed as a plain web-service.
ResCat's service catalog currently supports registration of Service Maps, Host maps, Abstract WSDLs, Concrete WSDLs and generic XML documents with it. It provides a web-service API using XSUL to add, delete, and query by ID for these documents. It also supports supports XQueries over these XML documents and uses the Sleepycat Berkley DBXML database for storing the XML documents natively. Lifetime management is provided for the Concrete WSDLs. A client side utility library to invoke the service and a command line shell for accessing the catalog are available. A web search interface for querying concrete WSDLs is also available here. The WSDL for the web-service API can be found here.
The data catalog part of ResCat supports registration of data collections available as THREDDS catalogs or provided as LEAD Metadata documents conforming to the XML schema. Once registered, the THREDDS catalogs are crawled using a metadata crosswalk to convert them to the LEAD Metadata schema, and indexed in the Lucene index. LEAD Metadata documents sumbitted in LEAD metadata schema are directly indexed without requiring crawling. The catalog can be searched for using the web-service API or the commandline client. Geo-Gui, a graphical portlet interface for querying the default LEAD data catalog, is also available here.
|Author: Yogesh L. Simmhan||
Last modified: $Id: index.html,v 1.10 2006/05/08 16:06:29 ysimmhan Exp $