Deterrent Examples

In this chapter, we would like to present some real-world deterrent examples that should definitely not inspire you.

Example 1

• Names should start with a capital letter
• Actors do not need to be stereotyped
• Use case names should follow the format <verb> <direct object>
• If the analyst decides to include a reference to the related business process (the grey "use case"), it should definitely not be modeled as a use case, let alone be placed within the system boundary and connected using the include relationship
• Use cases should be at the user-goal level without implementation details – the fact that messages are delivered via push notifications does not belong in a use case
• Deals with registration is an overcomplicated name – Sign up is much better
• Reads incoming messages is not a well-chosen name either. A use case should also reflect what the user wants from the system. The user wants to display messages, so the use case should be named Display messages

Example 2

• Missing system boundary
• Names should not be in the third person
• Typical functional decomposition – many includes
• 'Works with payment' says nothing and serves only as a package for other functionalities. It is not a use case.
• Confirms payment is just a step or functionality; it should not be a use case

Example 3

• It is not a use case diagram at all
• My account is not a system; it is a section
• The author just used use case notation to describe which services are called when two functions are triggered – don't do this

Example 4

• Requirements should be connected directly to the use case that realizes them
• A use case called "Requirements" makes no sense

Example 5

• A use case diagram represents use cases for just one system. Dividing the boundaries into two systems is incorrect.
• Actors should always be placed outside the system boundary
• If you decide to model a system as an actor (which we do not recommend), it should actually be a system. API is not a system.

Example 6

Use cases are tricky; even companies like IBM struggle to get them right:

Example 7

This example is from a tutorial presented by an online drawing tool used by thousands of professionals:

Example 8

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