The Design And Implementation Of Protocol Conversion Of Value-added System With Multi-external Interfaces

With the advance of 3G, increasing bandwidth and reducing charges, value-added services will continue to thrive. As for mobile internet, informatization, entertainment and e-commerce trends are obvious. Generally, value-added systems have to communicate with external gateways. With so many external gateways to deal with, it is inefficient to develop the communication module for each of them. In that case, increasing workload, unable to reuse along with repeated debuging and testing will hinder rolling out new products promptly.As a stable and effective communication module is indispensible to a value-added system, the paper proposes a communication pattern for data communication between value-added services and external gateways by analyzing data communication process. In the pattern, differences in communication with diversified gateways lie in differences of interface protocols. To solve the problem, the paper utilizes XML to describe message format to shade the defferences. In that way, the communication moudle can support a new interface without changing the main body of program.The key point is protocol conversion between value-added systems and external gateways. By extracting common communication mechanism, protocol conversion part is independent of communication process. The paper proposes XML-based protocol format description and PYTHON script to achieve protocol conversion. With XML-based protocol format description, main program splits a well-formed packet into fragments according to field format of source protocol; PYTHON script assembles fragments into a packet conform to destination protocol definition, and then forward the packet to destinaiton. In this way, program has dynamic loading capacity, namely, modifying XML files of protocols defintion or PYTHON script when program is running. That makes developing, debugging and testing easy.Last but not the least, a prototype is implemented accroding to design. Experiment shows that embedded PYTHON script in C++ can handle nearly 4000 packets per second; the prototype system can handle 280 packets per second in best cases; the prototype system cooperating with external interfaces can handle 200 packets per second. In practice, the prototype is used in a prepayment project to solve protocol incompatibility between prepayment protocol and service creation environment (SCE) of the company internshiped, becase private protocol is utilized in internal communication of SCE. Result shows that the design is a convenient way to solve protocol incompatibility between service systems and external interfaces. With that in hand, developers can focus on developing business logic, improving developing efficiency and maintaining consistency.