Figure 1.

The SKB architecture. The SKB is based on a three-layer architecture. Data sources are stored in the data layer. In the ontology layer data elements from these data sources are mapped to nodes in controlled vocabularies. The interface layer allows query, browsing and submission. For instance, the interface layer receives user requests, submits queries to the data layer through the ontology layer and obtains corresponding results. The three layers connect data from consumers (users submitting query) with data providers (data sources) via ontologies.