When a new customer registers he enters his details, period he is subscribing for and what subscription he’s taking - so TakeSubscription is included in Register.
However, a customer can also choose to take a subscription before he has registered, in which case the he will be asked to register as part of taking the subscription - in which case Register is an extension point of TakeSubmission. Can I have both an <> and <> between the same use cases or is that wrong? If so, how can I model it correctly?
The use case diagram should focus on what the user want to do (user goal) instead of what the system providing and how the service is being provided. Based on this the Register, Provide Personal Details and Choose Subscript Period should not be an use case. A user will not come to your system and just to register, right? Thank about what the user want to do with the system and you will know what should be covered in your use case diagram.
Thank you for your answer. I followed your advice and my model seems to make a lot more sense now, while avoiding problematic situations such as the one I described.
