Question

Well, I’m working on sequence diagram and I got confused when I found a some function could be a standalone function for a complete process the user may do, and it could be a sub process of a bigger process like

the first process: “historyClassRegistration(studentId)”
the second process: “allClassesRegistration(studentId)”

the student can register only history class
also he can register all classes which includes “historyClassRegistration” process inside

the question is:
should I draw the “historyClassRegistration” process alone with it’s sub-processes and redraw it again with it’s sub-processes in “allClassesRegistration”, or what can I do???

Answer 1

I think it probably depends on what use case the sequence diagram is trying to demonstrate.
It will also depend on the structure of the system.

If I had control of the design, the first operation would probably not exist. The type of class being registered for seems like it should be a parameter, unless the process for registering for classes is radically different between classes.

If your diagram was to show a student registering for all classes then there would just be a loop over a student.registerForClass(class) operation.

If your diagram was to show the internal execution of the allClassesRegistration(studentId) operation, then you might show a diagram with a loop over something like classRegister.register(studentID, Class).

If it was to specifically show a student registering for a history class, its really a scenario in which the student.registerForClass(class) is called with class = history. You might then show more detail of what happens to the object with which the student is registering.