Research On Theory And Method Of Protocol Interoperability Testing

Protocol Testing is a most important step in protocol engineering, its purpose is to ensure the protocol implementation executed steadily and reliably as the protocol specification, and it is significant for the quality assurance of communication production. Protocol testing includes conformance testing, interoperability testing, performance testing and robust testing. Conformance testing is to check whether the protocol implementation conforms with its specification, while interoperability testing is to check whether two implementations can interoperate properly. Both of them are the based assurance of the implementation's correctness. In the past, research on communication protocol testing mainly concentrated on conformance test. Although conformance testing is regarded as a necessary step on the way to achieving interoperation, it is agreed that it is insufficient to ensure interoperation of communication network entities. Some sort of direct testing of interoperation is considered indispensable.Design of testing system and generation of testing suite, are the two most significant problems in protocol testing. Testing system design is to solve the problem of testing method and testing framework (or architecture), while testing suite generation is to solve the problem of "thoroughness" , "standardization" , and "automatization" . The research work on interoperability testing can be roughly classified into two categories: general concepts and experiences of interoperability testing, and systematic generation of interoperability test suites.The work in this paper is concentrated on automatically generation method of interoperability test suite, testing coverage, testing reliability, etc. The following are included in detail: (1)Generation method of minimal-cost interoperability test suite. Test cost is a most important guide line to evaluate the test suite in test sequence generation algorithm. But most current research work on interoperability test only discuss how to generate transition-covered test sequence to cover all interoperating behaviors of interactive systems, under the condition that the whole systems can be formally described and controlled, but little is considered about the cost of test sequence. This paper will analyze the composition of the interoperability test cost in detail, construct composite FSM by reachability analysis of system, then use the edge-covered problem of digraph with edge-weight to generate the minimal cost test sequences, and finally give a approximate algorithm with greedy strategy. This method can effectively enhance the test efficiency.(2) Interoperability Testing method of partial-described system.In interoperability test there always exists such a situation: we needto test one system's interoperability with another exist system, but because we have not enough information about the specification of the existing system, or the system is too complex to be described, we can't formally describe the whole communicating system. In this case, we should generate test sequences to cover all possible interactive sequences to ensure the thoroughness of test. This paper gives a test method for the partial described system with digraph model, so called unilateral interoperability test method. A test criteria in interoperability test call minimal complete coverage criteria is bring forward and relative test sequences generating algorithm that satisfies the criteria is given. Test suite generated by this algorithm is a minimal set that can cover all interoperating transition sequences. Thus more interoperating error can be checked by executing less test sequences.(3) Testing reliability and dynamic test method The conventional method sometimes gives wrong test results because it is based on static test sequences. That is, faulty transitions that exist in the preamble and the postamble of a static test subsequence have an effect on testing a target transition. To solve this problem, a dynamic protocol test method is introduced in this paper. Dynamic protocol test method can avoid some local error of the implementation under test and apply more sufficient test on it, but the reliability of test result may descend due to the fault of local error indication. When the local-error-diagnostic algorithm is introduced to the dynamic test method, the problem can be solved effectively, the fault coverage can be increased and the running efficiency of test activity can be improved.