Multi-user environments, using 3D graphics, more and more find their way into areas like e-business, entertainment and cooperative work. Due to the increasing capabilities of hardware and network, even smaller devices, like laptop computers or PDAs, become suitable for the visualization of 3D graphics. A possible approach for distributing the 3D information is to use a server, which provides all clients with the necessary data. In this paper we define a client-server software framework, which supports the design of three-dimensional multi-user environments. We define requirements of the software infrastructure for a client-server framework that can provide a number of different 3D scenes, each with several users. The number of 3D scenes and users should be only limited by the hardware. Furthermore, we present a solution for each requirement and finally we discuss the results.