| This thesis presents the work of investigating remote flow meter maintenance technologies, and the design and implementation of an intelligent, mobile maintenance servicing system for IC card flow meters. The mobile maintenance servicing system consists of some mobile clients and a server communicating on the Internet. The repairers can take the mobile terminal of the system to the falling meters and carry out the maintenance on site, instead of taking the falling meters to maintenance centers, so that a lot of social resources can be saved.The thesis discusses the model of the mobile servicing system, the communication data design of the mobile servicing system, the steps of replanting embedded operating system, the design of embedded software, the oriented object persistent technology, and multi-layer enterprise application framework in detail. Based on these investigations, a mobile maintenance servicing system for IC card flow meters has been developed and delivered to Wuhan Natural Gas Co. Ltd.Firstly, in the system design, the whole communication data were classified into several kinds according to their different functionalities or services they provided, and put into corresponding "service frames". A "service frame" is made up with a service name, a type of the state code of implementation, a value of the state code of implementation, a list of parameters, the number of parameters and the value domains of parameters. The format of the service frame makes analyzing the data frame more conveniently, classifying the data frame more clearly, and expanding the type of the date frame more easily. With the service frame introduced, we can apply object-oriented methods to the design more naturally since it provides a natural way of data encapsulation.Secondly, in the design of communication data using GPRS, in order to resolve the problem that some GPRS modules can only identify standard ASCII coding, a technique of translating complex characters, such as Chinese characters, into standard ASCII codes was adopted, which makes the system can run well on different hardware platforms. Thirdly, in the design of embedded software, a multi-layer architecture replaces the traditional sequential function modules structure. The multi-layer architecture puts the sequential functions into the hardware layer, the application layer and the user interface layer vertically. The embedded software designed with this method could be easily replanted, modified and expanded.Finally, in the development of the server software, this thesis puts forward a seven-layer architecture based on the traditional architecture with three layers or five layers of enterprise application software. This seven-layer architecture improves the architecture with three layers or five layers of enterprise application software by expanding the business logic layer into basic logic layer, service-providing layer and advanced business logic layer. The software designed using this seven-layer architecture has less coupling between layers. Hence it could be replanted and modified more easily. |
