Role - Based Control of Shared Application

Collaboration often relies on all group members having a shared view of a single-user application. A common situation is a single active presenter sharing a live view of her workstation screen with a passive audience, using simple hardware-based video signal projection onto a large screen or simple bitmap-based sharing protocols. This offers simplicity and some advantages over more sophisticated software-based replication solutions, but everyone has the exact same view of the application. This conflicts with the presenter's need to keep some information and interaction details private. It also fails to recognize the needs of the passive audience, who may struggle to follow the presentation because of the amount of interaction details, display clutter or insufficient familiarity with the application. Views that cater to the different roles of the presenter and the audience can be provided by custom solutions, but these tend to be bound to a particular application. This thesis describes a general technique and implementation details of a prototype system that allows standardized role-specific views of existing single-user applications and permits additional customization that is application-specific with no change to the application source code. Role-based policies control manipulation and display of shared windows and image buffers produced by the application, providing semi-automated privacy protection, relaxed verbosity and added visual cues to meet both presenter and audience needs. The system's prototype was evaluated in a formal user study, in a task training scenario using a shared view. The study showed that adding visual cues improves accuracy, while privacy filters do not result in performance penalties but can even assist viewers.