Requirement Checking For Web Applications

Requirement consistency is an important stage to ensure the trustworthiness of software. It is shown that approximately 40% of software failures are caused by requirement inconsistency .In general, requirement consistency checking has three aspects: system design checking, refinement checking and implementation checking.For the first and second aspects, we can apply some static analysis techniques to find whether the design model or the refined model is consistent with the initial requirements. Since errors could be created while the design is refined and bugs could be planted in the implementation. So for an implemented system, it is still needed to check whether the system's initial requirements are satisfied, i.e. the third aspect of requirement checking.Currently, there are mainly two methods applied to the third aspect of requirement checking: testing and model checking. Testing is used for correctness checking of implementation. Test cases are derived from requirements. Since different tests are unrelated, only piece of the software can be checked during each testing. Thus testing can not guarantee the completeness, in other words, testing can not check the whole behavior of a system. Model checking can check the whole behavior of a system, but it is difficult to build a model from program code .This paper focuses on the third aspect of requirement checking for web applications. Since web applications have some special characters, such as navigation, hypermedia and so on, we proposed a new checking method based on its navigation character. The main idea is as follows. 1) Rebuilding requirements based on system implementation. We first get log file from user navigation,then after applying natural language process technique to the log file,we get use cases or the requirements for the implementation.2)Model transformation. Based on system's initial requirements and the requirements from implementation, we construct the corresponding use case models respectively, and then transform each use case model to SCA component model systematically.3)Requirement checking. By comparing the two SCA component models obtained from 2), we can check if the implementation satisfies the initial requirements. The SCA component model not only contains signature info, but also specifies system behaviours, thus, it can be used to compare on signature level and dynamic level.We build a prototype to support our moethod, and market information system [3] is employed to illustrate our methods and to perform analysis.