Consistency maintenance in Web-based real-time group editors

Consistency maintenance is a fundamental issue in many areas of distributed computing systems, including distributed databases, distributed shared memory systems and distributed groupware systems. Operational transformation is an innovative technique invented by groupware research for consistency maintenance in real-time group editors. This technique is particularly suitable for systems requiring high responsiveness and high concurrency and working in networking environments with high communication latency, such as the Internet. We propose an approach to applying operational transformation for consistency maintenance among multiple Java editing applets in the Web environment. Technical contributions include a novel compressed state vector timestamping scheme and related operation dependence checking and garbage collection schemes. These techniques are very general and could potentially be applied to other distributed computing systems using a star-like communication system architecture.