An Approach to Ensuring Consistency in Peer-to-Peer Real-Time Group Editors

Abstract

Real-time group editors allow distributed users to edit a shared document at the same time over a computer network. Operational transformation (OT) is a well accepted consistency control method in state-of-the-art group editors. Significant progress has been made in this field but there are still many open issues and research opportunities. In particular, established theoretic OT frameworks all require that OT algorithms be able to converge along arbitrary transformation paths. This property is desirable because group editors that implement such algorithms will not rely on a central component for achieving convergence. However, this has not been achieved in any published work to our knowledge. We analyze the root of this problem and propose a novel state difference based transformation (SDT) approach which ensures convergence in the presence of arbitrary transformation paths. Our approach is based on a novel consistency model that is more explicitly formulated than previously established models for proving correctness. SDT is the first and the only OT algorithm proved to converge in peer-to-peer group editors.