Supporting String-Wise Operations and Selective Undo for Peer-to-Peer Group Editing

Real-time group editing has been envisioned as an effective manner of collaboration. For years, operational transformation (OT) has been the standard concurrency control mechanism for real-time group editing, due to its potential for high responsiveness to local editing operations. OT algorithms are generally non-trivial to be error-free and are computation intensive. Recently, commutative replicated data types (CRDT) have appeared as an alternative to OT. The state-of-the-art OT and CRDT work still lacks the basic functionality found in single-user text editors. In particular, there is no published work that supports both string-wise operations and selective undo. This paper presents an approach that combines and extends OT and CRDT strengths. It is fully decentralized and supports string-wise editing operations and selective undo. Our performance study shows that it provides sufficient responsiveness to the end-users.