The MMI Ontology Registry and Repository: A portal for Marine Metadata Interoperability

To address important marine research and application challenges, there is a critical need for ocean observatories to share data in a way that is easy to use and integrate. Fulfilling this interoperability requirement is greatly facilitated by several standards efforts and recent advancements in Web technology. Although these infrastructures provide a fundamental capability for data sharing, there remains a gap from mere syntactic interoperability toward a more powerful, semantic interoperability, in which the diversity of terminologies, vocabularies, and conceptualizations across multiple observatories can be more effectively harmonized, exchanged, and fully integrated. In this paper, we describe the MMI Ontology Registry and Repository and associated semantic services developed by the Marine Metadata Interoperability Project. We present the architecture and the suite of key functions that allow data providers and users to include, use, and exploit semantic information in representative real world scenarios. We show how OGC Sensor Web Enablement services describing sensor systems and data products can be enriched with semantic references that client applications can readily resolve in corresponding semantic descriptions. Data discovery mechanisms enhanced with the provided semantic services are demonstrated with a Web data portal for integrated ocean observing systems. Services for resolution of Web identifiers, along with query and inference mechanisms, which can be accessed in a programmatic way, enable better data integration capabilities. We also demonstrate the ability to relate data quality flags across agencies, to fully describe processing tests and methods, as well as the ability to link definitions to bibliographic references, also registered using the MMI semantic portal.