Supporting scenario-based requirements engineering

Scenarios have been advocated as a means of improving requirements engineer ing yet few methods or tools exist to support scenario-based RE. The paper reports a method and software assistant tool for scenario-based RE that int egrates with use case approaches to object-oriented development. The method and operation of the tool are illustrated with a financial system case stu dy. Scenarios are used to represent paths of possible behavior through a us e case, and these are investigated to elaborate requirements. The method co mmences by acquisition and modeling of a use case. The use case is then com pared with a library of abstract models that represent different applicatio n classes. Each model is associated with a set of generic requirements for its class, hence, by identifying the class(es) to which the use case belong s, generic requirements can be reused. Scenario paths are automatically gen erated from use cases, then exception types are applied to normal event seq uences to suggest possible abnormal events resulting from human error. Gene ric requirements are also attached to exceptions to suggest possible ways o f dealing with human error and other types of system failure. Scenarios are validated by rule-based frames which detect problematic event patterns. Th e tool suggests appropriate generic requirements to deal with the problems encountered. The paper concludes with a review of related work and a discus sion of the prospects for scenario-based RE methods and tools.