Research On The Mobile Database Transaction Processing Model

With the rapid development of wireless network and hardware technology, themobile internet becomes a present research focus. The demand is still achieved by themobile transaction in mobile internet, so the mobile transaction processing is one of theessential features of mobile database systems. However, there are some factors, such asthe characteristics of the mobile transaction, the limitations of the mobile computingenvironment and the requirements of continuous processing when mobile hostdisconnects, making traditional transaction processing schemes no longer suited, so atransaction processing model aiming at the environment comes into being.This thesis performs an in-depth study on the existing typical mobile transactionprocessing model, summarizes the design ideas and inadequacies of key issues (such ashandoff, disconnection, long lived transaction, support weak consistency transaction) inthe mobile transaction processing. An extended optimistic two-phase commit mobiletransaction processing (EO2PC-MT) model is proposed based on it, the modelincorporates the design idea of the02PC-MT model: support interactive long livedtransaction; allow mobile host random move, meanwhile, makes up for the deficiencyof O2PC-MT model in the following aspects:①P roviding support for the weak consistency transaction:the mobile transactionsshould execute by the local copy of data before they are sent to the server. This canmake full use of the resources of the mobile host, and reduce the server load pressure,thereby enhance overall performance of the system.②I mproving2PC protocol adopted by O2PC-MT model: it provides backupMTCS to solve the performance bottleneck generated by single MTCS in O2PC-MTmodel, and to avoid MTCS failure result in obstruction.③Improving the algorithm of conflict detection in O2PC-MT model: Because ofthe possibility of disconnection, it is difficult to get the exact run-up time of transaction,this thesis adopts the timestamp interval and the principle of "strong-read weak-writepredecessor priority" to get timestamp. Some conflicts has been avoided largely in theprocess of getting global timestamp, so the work of conflict detection reduces sharplyon off-line mode.Finally, this thesis designs and analyses the prototype system of the EO2PC-MTmodel, and simulates its process using a representative instance, and verifies its validity.