What is Best Practices in Use Case Diagram

In the next video, you will see a few of the best practices that you should follow while drawing a use case diagram.

Some of the Best Practices while drawing a UML Use-Case diagram are:

1. Proper Order of Use Cases is not necessary
2. Use optimal amount of use cases & actors
3. If the Use-Case Diagram is too large, try to divide it into modules
4. Actors usually are nouns and Use-Cases usually start with Verbs
5. Each actor of the system should be associated with at least one use-case
6. Club multiple use-cases if possible, so as to reduce the complexity of the diagram

Video Transcript

Let's now see what are the best practices in a use case diagram. Firstly, in a use case diagram, the order does not matter. An actor could be associated to different use cases, while the order of the use cases does not really matter. One use case could be login, log out or check for an order, or invoice for anything, but the order does not really matter. Secondly, there should be few use cases and actors during the representation. You can restrict the number of actors and use cases to a specific use case diagram. General recommended number is 20 but is no hard constraint. It's good to restrict. To make it more simple and easy to understand, when a use case diagram grows too huge, it's a good practice to divide them into smaller use case diagrams, thereby dividing them into smaller modules. From your requirement document, you could see all the nouns gets converted to actors, and all the functionalities which starts with the verb becomes your use cases. In your use case diagram, there could be multiple actors and multiple use cases. Each actor will have to be associated to at least one use case, but vice versa is not true. For example, in cases of includes or extends, there could be some use cases which are not called by any actor, but are being invoked only by some other use case. Lastly, if there are multiple use cases, we can see cases where we can club few use cases. If it is all associated to a particular actor, it makes sense to club use cases and not to go too granular if it helps in making their representation clear.

Video Recap

• Use case diagrams in any order

• Actors can be associated with multiple use cases

• Keep the number of actors and use cases limited, preferably under 20

• Divide use case diagrams into smaller modules for simplicity

• Actors are converted from nouns and use cases from verbs

• Each actor needs to be associated with at least one use case

• Multiple use cases can be clubbed together if they are associated with the same actor

• Don't go too granular and prioritize clear representation