sharing single user application over distance

Share is a view-sharing system, where text-based applications are shared between participants of a real-time geographically distributed meeting through a shared window. Each participant sees an image of the running application on their screen, and has opportunity to interact with it by taking turns. We formed new insights by decoupling the view-sharing kernel from the floor-control interface, resulting in a system that can be customized to the needs of the participants and the group.

The screen snapshot illustrates how one user (Saul) sees a Share session involving three people. Each user sees:

  1. A shared view in this case of the emacs editor.
  2. The floor control interface. This example shows a pre-emptivefloor control system, where any user can "grab" the floor (ie. permission to type into the shared view) from the other. Saul is currently the only person who can type.

Another example of the same shared view with a different floor control interface. In this case, three users are using round-robin floor control. Saul again has control, but when he presses theNext Person's Turn button, control is passed onto Thorne. When he is done, it will be passed onto Ack, and then back to Saul and the cycle continues. Other users will not see the Next Person's Turn button until it is their turn.

we have built other floor control interfaces as well, including central mediators, pause detection, explicit release, and so on. What makes this all powerful is that the developer can devise a wide variety of floor control mechanisms that suit the characteristics of the individual participants and the group as a whole.

Primary Investigators

Ralph Bohnet (Internship Student)
Saul Greenberg (Supervisor)


  • Architecture for sharing and flexible floor control built.
  • Example Floor Control interfaces produced.
  • Papers published at various conferences.

Current Status

  • Completed. This was the first groupware system we built (late 1980's).