Due to Intranets and Internets, more and more information sources become technically available. An increasing number of users now either wishes to integrate these different information sources or to have a uniform view of these. As a consequence, the integration of heterogeneous information sources has become a field of investigation of growing importance. The schematic and semantic heterogeneity is one of the difficulties in the integration of heterogeneous knowledge and data bases. There are several distinct research and development areas explicitly or implicitly addressing semantic heterogeneity.
Most approaches reconcile the semantic conflict implicitly.
However, they do not help the user with the heterogeneity problem. Other approaches take the semantics of knowledge or data more closely into account and represent the semantics explicitly. The ontologies may be used to reconcile the conflicts or act as a global domain specification. However, there is still a great number of disciplines whose subtask is at least the integration of information. Although each research and development community has its own view of the integration of information sources the basic problems concerning for example the semantic and schematic heterogeneity remain the same.