Title: Earth Science Web Service Advertisement and Discovery
Primary Author: Di, Liping 
Organization: George Mason University
Co-Author(s): Peisheng Zhao, Christopher Lynnes

A new scalable Service-Oriented Architecture (SOA) is emerging as the basis for distributed computing and large networks of collaborating applications. More and more geospatial contents and capabilities for Earth science are available online as Web services which significantly enhances the interoperability of geospatial information and processing. As the number and variety of geospatial Web service increased rapidly, how to publish and locate a service is a big challenge. Currently, government agencies and international organizations are taking great efforts on developing and implementing the standards and systems for service catalog. NASA Global Change Master Directory (GCMD) offers a high quality directory system to enable users to advertise and discover Earth science data sets and services relevant to global change and Earth science research. The registry system of Global Earth Observation System of Systems (GEOSS) allows members of the intergovernmental Group on Earth Observations (GEO) to advertise their services based on industrial standards and provides a formal and searchable listing and description of registry entries. The service casting led by the Federation of Earth Science Information Partners (ESIP) provides scalable service advertisement with self-described information, and enables automatic service aggregation and discovery by search engines and feed readers. This paper focuses on how to advertise and discover a geospatial Web service in NASA GCMD, GEOSS Registry and ESIP Service Casting. The basic registry standards, mechanisms and information models are examined to architect service taxonomy and description. An example is also provided to illustrate the challenge and implementation of gesoaptial Web service advertisement and discovery.