Synchronous collaboration is the "same time, different place" mode of groupware. It is based upon a "What You See Is What I See" environment. Here, we concentrate on shared structured object spaces, also called multiple shared artifacts, which may simultaneously provide different representations for different users. This rules out any type of simple window sharing for the distribution task. Rather we propose some type of operation passing which is managed by an awareness server which forms a middle layer above a database system and below the client visualization engines. This awareness server also coordinates the viewports of all clients, called foci in the terminology of Rodden et al., and the cursors of all participants (nimbi). Besides discussing the major design issues which arise from this concept, including the notion of visual transactions which give up isolation in favor of awareness, we are able to present first snap-shots from a running prototype based upon TclD...