Research On Concurrency Control For Computer-support Cooperative Work

Along with computer technology, network technology and distributionaltechnical development, computer developed from single user working pattern tomulti-user collaborative work direction. Computer Supported CooperativeDesign(CSCD)came into being under this background, whose idea reflect thegroupware, interaction, distribution and cooperation of people's work mode in thenetwork. CSCD provieds the condition of communication and cooperation betweendesigners to support group work, which increases work efficiency and quality.Different designers mainpulated the concurrent operation to the sharinginformation inevitably have the conflict occured. Managing the consistency ofdistributed data is a critical issue for many collaborative systems. In a sharingmulti-user environment, in order to avoid inconsistency, increase efficiency,guarantees the successful cooperation, it is important to coordinate the action ofdesign members.Concurrency control mechanism is studied in depth which is used when multipleusers access sharing data simultaneously. Based on visited the platform to thedomestic and overseas famous collaborative design, some universal questions wassummarized which they met during design practice. In this paper, key mechanism ofconcurrent control during collaborative design was researched and discussed, enrichedand developed the related essential technology. The main contents are listed asfollowing:1. Collaborative design system frameworkIn the process of collaborative design, works between various department tendedto parallel integration, collaboartive design system faced concurrent engineeringrequired customizing designs according to designer's actual demands, satisfiedopenness and flexibility. Based on this kind of request, the thesis analyzed cooperativeenvironment, collaborative design characteristic, cooperative work pattern, andconcurrent engineering oriented requests, an open style system framework model hasestablished.2. Concurrency control mechanism in collaborative designThe paper stuedied the characteristics of engineering design, and traditionalconcurrent control methods, a conflict management system structure based onconstraint network and a conflict resolution system structure based on rule inferencehas been put forward and realized. In the conflict detection method, analyzed themethods for conflict detection based on constraint network during collaborativedesign. Using the constraint management system, established the constraint network,through satisfied the solution to make sure whethere the porcess is consistent. Becauseof constraint satisfies solution is a search question, therefore in the process whichconfirmed finally superiorly solution, chaos optimization method was used in order torapidly get global optimum solution and greatly improve convergence rate. Moreover,high consistency and executive frequency was expected.In the process of conflict solution, the paper analyzed the reasons for conflictemergence in details, establishment an knowledge library. Conflict was soluted byusing rules inference machanism. A fast pattern-matching algorithm was used duringrules inference in order to raise frequency. Futhermore, lower time and spacecomplexity was expected during the conflict resolution procedure.3. Access control modelCollaborative design process also must provided safety mechanism, in order toprevents sharing data was illegal gained and modified. The paper has discussedspecific demands of access control mechanism in coollaborative design. Object setconcept was imported based on traditional access control mechanism RBAC model.Different designers were divided into different sets according to their differentattributes, obtained different visit authorization. Lower system complexity wasexpected.4. Data exchange modelDuring collaborative design, designers in different place needed realizingeffective resources sharing. Therefore data exchange between various sites wasneeded. The paper discussed XML technology, designed and realized a datamanagement system based on XML technology and increment transmission. Inaddition, through the present research of the actual network topology and existingtoplogy discovery technology, strengthen network robustness and tuneability fromoptimizing network topology was discussed. A safe and fast network model wasestablished.Chapter 6 summarized all achievemnets of this dissertation, reviews innovationpoints and deficiencyt, and gives the further work in the future.