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

Abstract

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.

A CRDT Supporting Selective Undo for Collaborative Text Editing

“…There are two general approaches to collaborative editing, based either on operation transformation (OT) [6,7,10] or on commutative replication data types (CRDT) [8,9,[11][12][13][14]. With OT, a remote operation is transformed and integrated in the local site.…”

“…Currently, most related work can only apply undo to insertion and deletion of atomic objects [2][3][4][5][6][7][8]. To the best of our knowledge, only our previous work [9] supports selective undo of string operations. However, [9] does not account for possible undesirable effects of undo.…”

“…To the best of our knowledge, only our previous work [9] supports selective undo of string operations. However, [9] does not account for possible undesirable effects of undo.…”

“…Our current work is built on our previous work. The general view-model system structure is similar to the one described in [9]. The underlying scheme for character identifiers is similar to the one described in [11].…”

“…User studies show that users indeed expect to be able to undo other users' operations when working on common tasks [1]. In the research community of collaborative editing, selective undo is widely regarded as an important feature [2][3][4][5][6][7][8][9]. With selective undo, a user can undo an earlier operation, regardless of when and where the operation was generated.…”