Generic operation transformation scheme for consistency maintenance in real-time cooperative editing systems

In real-time cooperative editing systems, independent operations on any part of the shared document may be generated from multiple cooperating sites. It is very important and technically challenging to ensure that the effect of executing an operation at remote sites, in the presence of concurrent execution of independent operations, achieves the same effect as executing this operation at the local site at the time of its generation, thus preserving its intention and maintaining system consistency. In this paper, we investigate the technical issues involved in preserving intentions of concurrent operations, explain the reasons why traditional serialization-based concurrency control strategies and existing operational transformation strategies failed to solve these problems, and propose a generic operation transformation scheme for intention preservation and consistency maintenance in real-time cooperative editing systems. The proposed scheme has been implemented in an Internet-based prototype REDUCE (REal-time Distributed Unconstrained Cooperative Editing) system.