The Research And Implementation Of Embedded Mobile Database System-NimbleDB

The network environment of mobile computing has bright characteristics: mobility, disconnection, bandwidth diversity, scalability, weak reliability, non-symmetry of network communication, limits of powerability, etc. Mobile computing and unique characteristic make existing DBMS unable to support the mobile computing environment effectively, so must to mend or redesign traditional database, form a kind of database technology that can support the mobile computing environment in an all round way, that is Embedded Mobile Database.Transaction processing is a basic function of the database management system, it is used for maintaining the consistency of the data mainly , support the multi-user's concurrency visit, make user can query and update the database reliably. It is demand that mobile database system offer transaction processing ability too, in order to meet the mobile applied requirement. On Account of the paritcularity of mobile computing environment, it is necessary to consider the question which needn't consider in traditional computing environment in designing mobile database system, such as mobility of the client, frequent disconnecting, weak connection, switching in different areas and so on. So how to make server process mobile transaction perfectly become a very important subject.The goal of this subject is design an embedded mobile database system, called NimbleDB. NimbleDB considers practical data manage requirement, through the research on mobile transaction processing technology, copying technology and broadcasting technology, either use existing technology, or design new technology, avoid the fluence of mobile computing environment effectively, then form an embedded mobile database system to support application in various industries. Because of the basical position of mobile transaction process in EMDBS, in this subject, wo place our attention on mobile transaction processing. And we design NimbleDB on the basis of the research on mobile transaction processing. We consider mobile computing environmental confine and restriction on the mobile database transaction management, imbibe the experience of the past mobile transaction model, proposed E02PC-MT mobile transaction model. EO2PC-MT model considerssufficiently the requiremnt of strict consistency and weak consistency to data management in partical application, designs strict consistency mode and weak consistency mode. The two modes uses different transaction processing strategy, supports transaction mobilty, frequent disconnect and data consistency effectively.