This paper describes a service-oriented architecture for accessing resources through semantically designed portals called hubs. The services are dedicated to: (a) ontology management, (b) annotation generation from texts based on linguistic or machine learning techniques, (c) persistent storage of ontologies and metadata, and (d) semantic search in annotation bases or ontological databases. These services are, themselves, semantically annotated in order to facilitate their identification and composition. The application of our methodology is carried out within the e-WOK_HUB project in the geological domain.