I am currently working on refactoring a summer camp registration system to include some new features and will also be using it as the basis for a new after-school class registration system.For this new version of the system, I want to start out by writing use case descriptions for the registration process (and ultimately I plan to document all the use cases).I understand that the purpose of a use case is to accomplish a user's goal, but I'm still not sure how the registration process should be divided into use cases.Here are the options I've been thinking about:One big Register Student(s) For Classes use caseDivide it into separate use cases: Enter Student Information, Select Classes, Pay for RegistrationsHave separate use cases but also have a Register Student(s) For Classes use case which includes the more granular use casesAnother factor to consider is timing: parents may want to enter their students' basic information (name, age, etc.) prior to the time when registration begins, but of course some parents will complete the whole registration process in one sitting. Also, payment won't always immediately follow class selection; in some cases parents will be allowed to complete their payment later (within a 48 hour window).I read some articles about use cases on Alistair Cockburn's website but I'm still confused as to what the guidelines are for dividing up use cases in a case like this.My inclination is to go with option 3 since the system will have a wizard interface that could potentially guide the user through the registration from start to end, accomplishing the user goal of registering his/her student(s) for classes, but the included use cases could also be initiated on their own. I was also wondering if I should have a separate Modify Class Selections use case for the case when the parent logs back into the system later and changes class selections on behalf of the student, or whether that should just be an alternative scenario of the Select Classes use case.What would you recommend, and why? What guidelines should be used in general when analyzing use case boundaries, beyond the idea of a user goal?Update:I found this quote from the first chapter of Alistair Cockburn's book to be helpful:Depending on the level of view needed at the time, the writer will  choose to describe a multi-sitting or summary goal, a single-sitting or  user goal, or a part of a user goal, or subfunction. Communicating  which of these is being described is so important that my students  have come up with two different gradients to describe them: by height  relative to sea level (above sea level, at sea level, underwater), and  by color (white, blue, indigo).It seems to me that Register Student(s) is a summary level goal, since it could potentially take multiple sittings to complete. The line is blurred in this case, but I think this idea of a summary use case suggests that my approach #3 above is a reasonable one.
Use case decomposition for class registration system
requirements;use case
In short, there's no real right or wrong answer here: it's one of those things where its up to your work style and work flow. Personally, I like to take all the users that could possibly ever use my system, and then list them out. ParentStudentTeacherAdministratorThen, I write ALL the different things those users would want to accomplish for my systemParentRegister Child/Children (Could be more than one child)StudentRegister ThemselvesTeacherView student's who've registered for their classAdministratorRegister StudentsMove student's to different sectionsFinally, each one of those behaviors becomes a use case, with main flows, and alternate flows, such as a parent entering an invalid class, or an administrator trying to move a student into a full section. You may find that some of these use cases are very similair and that's fine, feel free to combine them. At least this way you know you aren't missing any!