This new reference provides a detailed road map on how semantics and Semantic Web technologies can play a significant role in creating a middleware system and in managing heterogeneous software systems. The book builds a rigorous approach towards giving the declarative descriptions of components and services a well-defined meaning by specifying ontological foundations and by showing how such foundations may be realized in practical, up-and-running systems. An introduction to the basics of middleware technology is provided, along with a discussion of ontologies, to help readers who are not familiar with the area to get the necessary background information.