WWW is a repository of information mainly oriented to human consumption. The lack of explicit and formal expression of data semantics makes the Web increasingly difficult to use and exploit. To remedy it, Knowledge Management Sphere (KMSphere), taking advantages of Semantic Web, Web Services and Virtual Organizations, is proposed to explore important aspects of service-oriented and ontology-driven knowledge management on the grid. By building two kinds of mappings, ontologies construct a knowledge space on top of data repositories. KMSphere, based on OGSA, emphasizes how to organize, discover, utilize, and manage the knowledge resources in that space. This paper describes in detail the architecture of KMSphere.