MMI Web Services Luis Bermudez, John Graybeal The Marine Metadata Interoperability (MMI) Project promotes the exchange, integration and use of marine data through enhanced data publishing, discovery, documentation and access. One of our goals is to provide interoperable demonstrations bringing together heterogeneous data sets. We will explain the design architecture of Tethys, which is one if these interoperable experiments. We will explain how semantic mediation services can be used by both data producers and data clients, and describe the implementation of these services by both entities. _________________________________ Luis Bermudez, John Graybeal 7700 Sandholdt Road Moss Landing, CA 95039-9644 email: bermudez@mbari.org