From Undo to Multi-User Applications

The interaction history of a document can be modelled as a tree of command objects. This model does not only support recovery (undo/redo), but is also suitable for cooperation between distributed users working on a common document. Various coupling modes can be supported. Switching between modes is supported by regarding different versions of a document as different branches of the history. Branches can later be merged using a selective redo mechanism. Synchronous cooperation is supported by replicating the document state and exchanging command objects. Optimistic concurrency control can be applied because conflicting actions can later be undone automatically.

• Type: Conference
• Year: 1993
• Where: VCHCI
• Authors: Thomas Berlage, Andreas Genau
• Keywords: Command Objects, Document, Human Computer Interaction, Various Coupling Modes, VCHCI 1993