移动平台下实时协同关联图文档模型一致性维护算法研究  

Research for Consistency Maintenance of Real-time Collaborative Associated Graph Model in the Mobile Platform

作　　者：高丽萍[1,2] 张鑫 GAO Li-ping;ZHANG Xin(School of Optical-Electrical Computer Engineering,University of Shanghai for Science ＆ Technology,Shanghai 200093,Chin;Shanghai Key Laboratory of Data Science,Fudan University,Shanghai 200093,China)

机构地区：[1]上海理工大学光电信息与计算机工程学院,上海200093 [2]复旦大学上海数据科学重点实验室,上海200093

出　　处：《小型微型计算机系统》2018年第8期1700-1706,共7页Journal of Chinese Computer Systems

基　　金：国家自然科学基金项目(61202376;61572325)资助;上海市自然科学基金项目(15ZR1429100;17ZR141900)资助;上海市数据科学重点实验室重点开放课题项目(201609060003)资助

摘　　要：移动平台下实时协同图形编辑系统是协同交互式应用的重要分支.在图形编辑系统中,不同图形对象之间往往存在某些约束和关联关系,而传统文档一致性维护算法的研究大多是在无约束关系的线性文档下展开的,且仅支持基本的插入(Insert)、删除(Delete)、更新(Update)操作.本文在传统操作转换算法所能支持的基本操作(Create、Delete、Update)的基础上,拓展了位移(Move)操作,关联操作(Relate)和关联解除操作(Relieve),使得图形对象间的位置属性之间可以出现联动的效果.对象间位置关系被映射成关联图文档模型,根据非线性模型下不同操作类型之间产生的并发冲突类型,分别设计相应的冲突消解策略,维护实时协同编辑下共享图形文档的一致性.当包含多操作类型的图形编辑系统应用于移动平台下,由于移动网络的不稳定性,会导致现有的以稳定网络为研究前提的乐观并发控制算法不能适用于新的应用场景下.所以针对移动网络环境下信号不稳定的特点,本文亦对传统操作转换控制算法进行适当改进,基于客户端对丢失操作提出重发请求和服务器端处理该重发请求的机制,设计了不稳定移动网络平台下并发控制算法.最后本文在Android平台下开发了移动协同图形编辑系统Co-Paint,并通过相关仿真试验进一步验证了以上控制算法和转换函数的正确性与可行性.Real-time collaborative graph editing system is one of the most important branches of collaborative interactive applications in the mobile platform. In a graphical editing system, there are certain constraints and associations between different graphic objects. However, the traditional consistency maintenance algorithm is mainly conducted in the linear document with unconstrained relation- ships, and only supports three basic operations （Insert, Delete, Update）. Based on basic operations （ Create, Delete, Update） supported by traditional operation transformation algorithms, this paper extends some operations （Move, Relate, Relieve ） which can represent the linkage effect on the location property of graph objects. And the relationship between objects is mapped to the associated graph docu- ment model. According to types of concurrent conflict generated by different operation types under the non-linear model, some reason- able conflict solutions are designed to maintain consistency of the shared graphical document under real-time collaborative editing. Be- sides, when a graphical editing system containing multiple operations types is applied to the mobile platform, the existing optimistic concurrency control algorithm based on stable networks may be not applicable to the new scenario because of the instability of the mo- bile networks. In view of the characteristics of signal instability in mobile network environment, the traditional OT control algorithm is improved in this paper and new concurrency control is also introduced. Based on the mechanism of sending the re-transmission request for lost operations on the client site and processing it on the server side, the concurrent control algorithm in the mobile platform of un- stable network has been designed. The paper develops a mobile collaborative graphics editing system named as Co-Paint, and some simulation test further verify the correctness and feasibility of the above control algorithm and conversion functions.

关 键 词：移动平台 协同计算 关联图文档 操作转换 一致性维护 

分 类 号：TP393[自动化与计算机技术—计算机应用技术]