usecase diagram

Question

I am designing a use case diagram for a system that includes a special type of hardware/device that generates multiple events for it self. How do i draw a Use case diagram for those system generated events or how will i proceed with the diagram.

Abdul Khaliq

Answer 1

State Machine Diagrams might be a better choice for what you need.

Answer 2

This is the book on use-cases: http://www.amazon.com/Writing-Effective-Cases-Software-Development/dp/0201702258/ref=sr_1_3?ie=UTF8&s=books&qid=1244456081&sr=8-3.

The drawing part og usecases is not important, it's the textual part thta matters...

Answer 3

I don't think I would use a use case diagram at all in this case. The special device is a part of the system, and use cases are best at showing interactions with the system from outside, typically from human users.

To expand a little, consider a desktop application that uses a timer (analagous to your " special device) to fire some event, as many do. I would never use a use case to show the timer firing. Instead, I would probably use an activity or asequence diagram to explain the timer event handling.

UML does not require you to produce any specific set of diagrams. If youy are finding a particular type of diagram hard to draw or use, it probably isn't necessary for your design.

Having said all that, if you are wedded to the idea of use case diagrams, you can make your special device an actor in a use case and show it using the other parts of the system.

Answer 4

You should model your use cases based on how the system is going to be used. Not every HW-generated event needs to have a use case modelled for.

You design use case diagrams to give a high level overview of how the target system is potentially going to be used. When you find that a particular hardware event 'plays a role' in one of the use cases modelled, then you add this HW device (timer, sensor, etc...) as an actor for the use case.