An Embedded Client The C / S-systems And Applications

New business and applications boom with the development and popularization of social informationalization, and the maturity of Internet and wireless network. Embedded device and wireless communication are two technologies of development fast recently. Embedded device may not only operate data effectively when disconnected from the network and the enterprise, but also exchange data from center data source via wireless network. It makes work more flexible and effective. But it is a distributed compute environment which has itself features and difficulties , so some traditional technologies can not support this application effectively. It must redesign structrue of system and layout data' s assign in this new system.This paper mainly discuss a type of study and implementation in C/S system based on embedded client, and application programming on it. The system is a distributed application environment, because it differs from traditional C/S structure, this paper uses an extend form base on traditional C/S, Client/ Synchronization Server/Server 3-tier structure. In client side, a part of center database data are replicated on which embedded device is used. The author develop application program using J2ME MIDP in order to manipulate local data for user. In server side, the author creates center database and develop synchronization server program which takes charge of dealing with client request and synchronizing data between client and server. This paper brings forward a synchronization scheme combines session connection with data gain base on changed, and client side data priority base on timestamp. When the system is running , embedded device manipulates data in disconnection status which results in difference from center database. Changed data is stored in client side. Then client reconnects the server via wireless network and synchronizes the changed data to center database using the synchronization scheme. The server uses the update data to process the next manipulation.First, it introduces the featrues of embedded system and device briefly, then describes the concept of the data synchronization technology and enumerates the technology of some systems. Second, we discuss the system structure, synchronization scheme and function modules. Third, it describes practice software programming and implementation combine with an application of low voltage transformer substation. Last, this paper puts forward the ways of improvement of the following work base on the recent work.