A hierarchical peer-to-peer reduction and merging framework for efficient operational transformations in collaborative editing

The primary goals in a synchronous, real-time collaborative editing system (RTCES) involve ensuring a high level of concurrent access (editability) to users while maintaining the properties of the CCI model (consistency, causality-preservation, and intention-preservation). The field of RTCES research has advanced in techniques to overcome some of the challenges inherent in the support of synchronous editing of a shared document via Operational Transformation (OT), however current OT techniques require high message and storage costs. Their performances degrade as the storage for past operations into history buffers increases. In this paper, we present a novel algorithmic framework for history buffer reduction, which minimizes the size of the history of operations and reduces storage overheads. We show how this algorithm can be pipelined within a hierarchical document tree, enabling for further efficiency and opportunities for intention preservation - currently a hard problem. Further, we show how to distribute this algorithm in a peer-to-peer RTCES and present empirical simulation results that demonstrate the validity of our approach. Our contributions are breaking new grounds in the field of synchronous collaborative editing.