Achieving data consistency by contextualization in web-based collaborative applications

Recent years have witnessed the emergence and rapid development of collaborative Web-based applications exemplified by Web-based office productivity applications. One major challenge in building these applications is maintaining data consistency while meeting the requirements of fast local response, total work preservation, unconstrained interaction, and customizable collaboration mode. These requirements are important in determining users' experiences in interaction and collaboration, and in meeting users' diverse needs under complex and dynamic collaboration and networking environments; but none of existing solutions is able to meet all of them. In this article, we present a data consistency maintenance solution capable of meeting these requirements for collaborative Web-based applications. Major technical contributions include an efficient sequence-based operation transformation control algorithm based on the concept of contextualization, an operation broadcast protocol for supporting a variety of collaboration modes, an operation replaying algorithm for ensuring fast local response and efficient remote operation replay, and a set of communication protocols for managing the integrity of collaborative Web-based sessions. The proposed solution has been implemented in a prototype collaborative Web-based editor WRACE and the correctness of the solution is formally verified in the article.