- Prof. William Burrows, University of Washington, Seattle
Identify use cases from stakeholders, write use case scenarios with Flow of Events editor
Understanding the business values of customers is the key success factor in any software development project, especially when technical values may not align with business values in many cases. The use case approach helps technical people to keep business values in mind when making technical decision. The use case approach is proven to be effective in capturing functional requirements in customer perspective that align with customer's business values. Visual Paradigm enables use case identification by supporting features like Use Case List, use case diagram, flow of events, etc.
It's impossible to identify all use cases by asking simple question like "Mr. User, please tell me the functions you need." There are techniques in capturing user requirement and one is to start by knowing who will be the users of the software. Think about this, if you are going to develop an online learning system, your client may tell you: "We want a system for both our teachers and students." That's typically the kind of information you can get from users and that's why you need an actor-driven approach in finding use cases.
The Actor List is where you can record and manage the roles who will be using the system. The goals of actors can be recorded, and be further derived into use cases to use in detailed use case analysis and use case modeling.
While use case captures user goal without covering how to achieve the goal, a use case scenario (i.e. Flow of Events) provides a medium for system analyst to capture the interaction between user and system, describing the "how" aspect of use case. By reading the steps involved in Flow of Events, user can immediately tell whether the function can meet his/her need. Wrong assumption can be corrected without having to wait until any prototype or executables. With risk tackled in early stage of development, a more accurate project planning can be performed.
In addition to the main flow, describe the steps that run in exceptional cases.
Break-down a step into sub-steps for more detailed description.
Know the high level system flow by hiding the sub-steps.
Describe the different possible flows of a use case.
Reference to related actors, use cases and requirements in steps.
Apply if-then-else or looping in describing the steps.
Visualize the flow of events with a UML sequence diagram.
Visualize the flow of events with a UML activity diagram.
Specify how to test the steps in flow of events.
Specify the primary actors who can gain a measurable result by achieving a use case, and secondary actors who assist in achieving the use case.