Charging of services in a distributed system will become more and more important for systems which are utilized commercially. Such an important distributed system exists in form of a Computational Grid (CG), offering a variety of services on different layers to many users, academic and industrial ones. Although by itself a CG defines a research and operational problem area, the dedicated task of charging CG services, by definition a new grid service, has to be considered crucial, once a large number of users will share computational resources as well as services offered by a CG. Safely assuming that the Internet will form the all-embracing communication technology in use in the near future, Internet-based communication layer services will offer the potential to differentiate higher layer and distributed services of the CG. Therefore, the Internet communication model of the Differentiated Services Architecture will underlie an open and flexible CG architecture in support of basic and v...