Supporting flexible communication in heterogeneous multi-user environments

A flexible communication model for multi-user interfaces is presented. It allows for coupling arbitrary user interface objects between heterogeneous applications dynamically. When coupled, UI objects are synchronized by broadcasting events and re-executing the corresponding actions in the different application environments. To be coupled, objects have to be compatible, but not necessarily identical. The communication mechanism is based on a centralized server. In addition to multiplexing callbacks, it also handles arbitrary remote procedure calls in a standardized way, thus allowing the transfer of internal state information between applications. Our communication mechanism is implemented as a set of primitives that extend an OSF/Motif-based UI toolbox library. It can be easily used to develop multi-user interfaces in very much the same way as single-user applications, or to extend single-user applications to multi-user ones