Research Of Concurrency Control Technology For Mobile Transaction

With the rapid development of the computer network technology and wireless communication technology, as well as extensive use of mobile devices, mobile computing technology is increasingly maturing. In the mobile computing environment, mobile users can not change the effects of the physical location of a mobile device to access to any data on the server anytime and anywhere. As in the mobile computing environment mobility,frequent disconnection,asymmetry of wireless computer network communication,limited communication bandwidth, etc. Such features make the traditional distributed database technology applications in mobile computing environments face many challenges, which makes the mobile database technology has become a research hotspot.Mobile transaction processing technology is one of the key technologies to the mobile database technology, transaction processing mainly support multi-user concurrent access,maintain data consistency, ensure that mobile transaction can be timely and efficient completion of the database to query and update operations. In the transaction processing, there are several transactions must be executed concurrently. However, conflicts may arise between the number of concurrent transactions (for example, at the same time to read and write the same data table,the same record and the same data item, etc.),To ensure the correctness of the results of transaction processing, especially in the mobile environment to maintain data consistency and improve transaction concurrency, So an ideal design of a mobile transaction concurrency control protocols to become the main purpose of this research project.This paper studies the affairs of the traditional concurrency control techniques, the current popular mobile transaction processing model and a variety of mobile transaction concurrency control techniques.Matters affecting the performance of transaction concurrency control have mainly concurrency,re-start rate and the rate of cut-off time delay. In order to improve mobile transaction concurrency and transaction throughput, reduce transaction response time, Tthis paper presents a new concurrency control protocol-data lock optimistic concurrency control protoco DLOCC. DLOCC is combined with the advantages of locking concurrency control protocol and optimistic concurrency control protocol, Large amounts of data on the server classify according to an updated times and access probability of data items, based on different data types using the appropriate concurrency control protocol.The simulation experiments showed that DLOCC is feasible and effective and efficient use of system resources in mobile environments,In the paper, according to the idea of data classification, Mobile client buffer is divided into three areas according to different data types:private data area, shared data area, public data area, each divided into fixed-size data blocks, a replacement algorithm based on the data update frequency and in recent times have not been visited.The replacement algorithm maintain effectively the data consistency of Mobile client cache.