In this section, we give a brief tour of the modules which constitute the Jupiter system. The functionality of these modules is exposed through a number of interfaces, known as the base interfaces, which are fundamental to Jupiter's design. For each facility provided by Jupiter, we first present its base interfaces, and describe it in terms of the responsibilities it encapsulates. We then describe the current implementation of that facility. It is important to note that these are examples showing the current implementation of the Jupiter facilities. The design of Jupiter allows these implementations to be changed easily.