Concurrency Control For Multilevel Secure Database In Mobile Broadcast Environments

With the rapid development of computer technology and mobile communication technology, a new computer modle-mobile computing harvests amazing growth. Nowadays, an increasing number of database application has been used to support concurrent transactions through the mode of broadcasting, plus information system has more and more sensitive information processing on it. Therefore, the priority of mobile computing is to resolve the concurrency control problem of multilevel secure database in the mobile broadcasting environment.Firstly, the thesis briefs the background and status quo of research in mobile computing, mobile databases, multilevel secure database and concurrency control.Secondly, under the premise of the research status at home and abroad, seeing that the existing concurrency control of multi-level security cannot fit into such features as the mobility and frequent disconnection in mobile network environment, therefore, LFMVO-2PL protocol is proposed. The protocol prevents the creation of covert channel, the occurence of retrieve exception, the starvation of high-level transaction is also relieved. At the same time, it provides a multi-level serializable transaction scheduling, improves concurrency and reaches security requirements of multilevel secure database in mobile broadcast environment.At last, a performance analysis of LFMVO-2PL protocol is carried out through simulation experiment, and compared with other protocols. The results of the experiment show that the LFMVO-2PL protocol has higher transaction throughput, can guarantee the correctness of multi-level transaction scheduling and performs better than other protocols.