The Study Of Concurrent Control Based On Operational Semantic In Collaborative Editing

Computer Supported Cooperative Work(CSCW)is more and more popular with the rapid development of information technology and network technology.Collaborative editing is a research focus of CSCW,and it has a broad application prospect.It has received extensive attention of people since it was put forward.It is an extension of single user editing that supports multiple users editing the shared document together with no limited by geographical location,time and space segmentation.It enables collaborative users make full use of their time and improve the efficiency of work.The concurrent control and consistency maintenance is the main direction of the research in collaborative editing.This paper focuses on the study of concurrency control and consistency maintenance in collaborative graphics editing.In terms of concurrency control,we propose a transformation control algorithm,named TICOT(Two-side Improved Context-based Operational transformation).In terms of consistency maintenance,we introduce the graphics semantics,make the definition of the semantic operation,and design a suitable transformation function for graphical editing environment.The parameter of transformation function is semantic operation and normal operation.The algorithm which we proposed solves four types of consistency maintenance including semantic consistency.For concurrent control,we introduce the common used concurrent control algorithms and their insufficiencies in collaborative editing.We also analyze and discuss the Context-based Operation Transformation algorithm(COT)and the problem of redundant about operation transformation.By introducing the conception of the operational sequence and the total order of the operational sequence,the COT algorithm is improved from two sides:the combination broadcast of local operations,the reception and transformation of remote operations,and we call it TICOT.At last,we make one simulation about the execution instance which used the improved algorithm.We can verify that the improved algorithm could effectively reduce the execution time of remote operations by do the simulation experiment about COT algorithm and TICOT algorithm.For consistency maintenance,we introduce the problem of semantics is in graph editing.Firstly,we do the classification and expression about the semantics in collaborative editing,and design semantic operation that suitable for context-based conditions.Secondly,we made a detailed analysis on the conflict or compatible relation between the normal operation and the semantic operation in the collaborative graphics editing.Then,according to the definition of the inclusion transformation function,we design the Specific transformation function for collaborative graphics editing by setting the priority of operations.Finally,we theoretically prove the validity and correctness of the proposed algorithms that combine the TICOT algorithm and inclusion transformation.In the end,we design a prototype of collaborative graphics editing.We implement the transformation control algorithm and transformation function in prototype,and verify the feasibility of the overall concurrency control algorithm through a prototype example.