Research On Distributed Version Management System

The computer-supported collaborative design(CSCD) is a combination of design, computer technology, and network technology. It can satisfy the requirements such as distribution, interaction, and dynamism. Large collaborative projects such as aircraft design involve multiple disciplines and participants from different fields and regions. In this process, multiple rounds of iteration should be carried out, so it is necessary to record characteristics of each stage. That is, the design version should be managed effectively. Distributed version management can help designers to manage a large amount of information during the design and avoid the loss and confusion of the middle information. Therefore, it is meaningful to study distributed version management in depth due to its theoretical significance and real application. In practical implementation, the distributed version management model is simple and the concurrency control efficiency is low. This paper contains the following tasks:1. This paper analyzes the key issues involved in the distributed version management and the design process of large-scale collaborative design projects, and determines the research objective.2. The traditional version management model cannot be used universally and with the traditional model, it is difficult to achieve distributed deployment. To handle this, a semantic model is proposed to organize unstructured data into structured data, which can be used to describe the changes of design objects. Furthermore, a semantic-based distributed version management model(SDVMM) is proposed. The comparison experiment shows that the SDVMM is superior to the other version management model in time and space overhead.3. Considering the poor adaptability and low running efficiency of existing concurrency control algorithms, this paper proposes an adaptive concurrency control algorithm based on collision rate prediction(ACC-CRP). This algorithm divides the concurrency control into two stages, including information collection and policy selection. In the information collection stage, a prior transaction queue is used to ensure the execution of the transaction and the transaction execution state of the system is collected by the cycle conflict queue. The policy selection stage uses the improved weighted moving average method to predict the next phase of the conflict rate. Experiments show that when the transaction arrival rate is high, the ACC-CRP algorithm can result in high transaction execution efficiency and accurately perceive the change of the collision rate.4. Based on the existing theory, this paper designs and implements the basic function of the distributed version management system on the aircraft cooperative design platform based on B/S and C/S hybrid architectures, and the test results show that the proposed model and algorithm are feasible and practical.