Abstract: Semantic Grid applications based on the cooperation of Grid Services need semantic modeling tools and functions to access and manage ontologies stored on the Grid. Although many tools and methodologies exist for ontology editing and management, they often work in a centralized way and are not available on the Grid. The paper proposes a distributed ontology management framework where ontology schema is replicated and instances are distributed among nodes of the Grid. A distributed ontology kernel that offers querying and updating APIs and a graphical query interface for ontology browsing have been fully designed. The kernel leverages distributed data management functions offered by the Grid middleware to store and access ontology fragments. It has been embedded into an ontology-based workflow editor allowing distributed users to design and execute bioinformatics applications. Domain ontologies, partitioned and managed by the ontology kernel, are accessed by the editor enhancing workflow composition. The ontology distribution allows to design a complete application whatever availability of Grid nodes.
