Concurrency Control Research And Implementation In Cooperative Editing System

In cooperative editing systems there will be carried out the conflicts when users operate the share information at the same time. How to resolve conflicts and to maintain data consistency is a key issue in the cooperative editing systems.Firstly, the paper introduces the cooperative editing systems'concept, architecture and its core content, and lists some of the existing cooperative editing systems. Then the paper compares with the existing concurrency control methods, studies their advantages and disadvantages and lists the fields of application, as the existing concurrency control methods are not yet fully meet the needs, this thesis proposes a new consistency maintenance algorithm based on previous research on concurrent control, which combine the distributed OPeration Transformation (dOPT) with the document mark method, and a directory path lock method for the auxiliary. This algorithm combines the advantages of the dOPT and the document mark method, and maintains the users'intent and the data. It is convenient to users to browse the content with using the form of the file directory tree to display the share documents in users'Interface, and control the users'concurrent access using the directory path lock method to maintain the integrity of documents'structure.Based on the above algorithm this paper designs and implements a cooperative editing system, which based on the B/S mode. It realizes that the algorithm is better than the original concurrency control methods on the space and time complexity.