Currently, most users upgrade and transform their existing systems. Can we still use the use case technology in this case? Fortunately, the answer is yes. You can follow these steps:
1.Determine system boundaries: IdentifyActorTo define system boundaries;
2. restructured the use case model: briefly capture and describe the use case model of the existing system.
3.Extended use case model supplement use case Conventions: Add new use cases or expand existing use cases according to system upgrade and transformation requirements. Before expanding existing use cases, the basic event stream and alternative stream Involved in the use case need to be supplemented to describe the required new behavior based on them;
in this way, during the transformation of the existing system, gradually reconstruct the use case model and description of the entire system.