The Global Change Master Directory (GCMD) provides discovery/collection-level metadata of Earth science resources and offers scientists a comprehensive and high quality database to reduce overall expenditures for scientific data collection and dissemination. The GCMD maintains several web services for discovering and retrieving Earth science metadata and the Earth Science keyword taxonomy. The web services are: (1) Metadata Web Service (MWS), (2) Keyword Management Service (KMS), (3) OpenSearch, and (4) RSS/ATOM.
The Metadata Web Service is a RESTful service for retrieving and publishing Earth science resources, including data set descriptions, service descriptions and ancillary descriptions. The Keyword Management Service (KMS) is a RESTful web service for maintaining keywords (science keywords, platforms, instruments, data centers, locations, projects, services,resolution, etc.) in the GCMD system. The KMS allows access to the keywords as SKOS Concepts (RDF) or as XML objects. OpenSearch is a web service for publishing results in an OpenSearch standard response suitable for syndication and aggregation. This feature allows aggregators to combine searches from multiple search engines. The RSS/ATOM feed allows users to subscribe to new and updated metadata collections in the GCMD. Users can also subscribe to a feed based on a specific search criteria.