Research And Implementation Of System Communication Based On Network Connected Multi-media Terminal

Network products have penetrated every corner of our daily life with the rapid development of information science and technology.Embedded Linux based terminals-PDA,mobile phones,set-top box,network tools,car-computers,security system,medical instrument,audio and video equipment,and also information home appliances,etc,have also become an important part of IT products.Embedded Linux based terminals,making full advantage of Linux operating system,reduces the cost for developing related software;they fully meets the needs for the integration of functions,economization of resources and acceleration of booting when undergoing cutting and transplanting.Nowadays,Embedded Technology has evolved to such an extent that the processing capacity of embedded system far exceeded its control over terminals.Thus it is a tremendous waste of resources if a traditional way(viz.simply responsible for playing videos and surfing) continues to be employed.Meanwhile,the development of network and communication technologies increases people's expectation of control,management,and communication capacities,along with an increasingly emerging of network.In the thesis,the state-of-the-art report and the trend for future development of terminal system communication is presented.Based on the research of system communication of embedded Linux based terminal,the design mode of hierarchical network was put forward;the function of related module and its processing procedures are investigated.Finally,C/C++ technology is employed to realize the Service logic of terminal communication,the real-time connecting mechanism of network and the effective transmission of network data.The module of system communication is categorized into four components: management modules of network connection,transmission layer,application layer and business logic.Their functions are defined as follows respectively.Management module of network connection is responsible for the connection and disconnection of network socket,the data transmission and reception.Management module of transmission layer realizes the data subcontracting and verification,guarantees the accuracy of data sent to the application layer.Management module of application layer is responsible for packing data group of service layer into Application-Level frames,and decoding data from transmission layer into Application-Level frames. Management module of business logic manages the responses of orders.Any requirement alteration only needs the update of management module of Service logic, keeping unchanged the data transmission and reception of bottom layer and thus improving the maintainability of programs.After subjected to testing,the module of system communication implemented in this thesis is self-contained in function and stable when operating and realizes the distant control over terminal products by platform management system.It possesses good extensibility and lays a solid foundation for the development of follow-up versions.