Outline the Use Case Suite:
It is tempting to skip this step and jump directly into writing a use case. After writing one use case, you would write another, and so on. That process would be like coding your application without outlining the design first. You would never really know how much further you need to go before you are done, if you were spending too much time in one area, or if you had forgotten other important areas altogether.
The second step in our breadth-first approach to writing use cases is to outline the use case suite. A use case suite is an organized table of contents for your use cases: it simply lists the names of all use cases that you intend to write. The suite can be organized several different ways. For example, you can list all the classes of users, and then list use cases under each.
One particularly good use case suite organization is to use a grid where the rows are classes of users and the columns are business objects. Each cell in the grid will list use case names that are done by that class of user on that type of object. For example, in an e-commerce system, shoppers would have use cases for adding and removing products from their shopping carts. In contrast, administrators might have some very different use cases, for example, calculating the percentage of abandoned shopping carts.
The advantage of using an organized list or grid is that it gives you the big picture, and helps you put your finger on any area that needs more work. For example, in the e-commerce grid, there might be a business object "Coupon". It is obvious that shoppers use coupons, but it is easy to overlook the use cases for administrators who must create coupons. If it is overlooked, there will be a clearly visible blank space in the use case suite. These clear indications of missing requirements allow you to improve the requirements sooner rather than get bogged down in too many frustrating requirements changes later.
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