Extend all use-case

Question

I have a question about uml and extend notation of use-case. How I can extend all use case. For example if I created a connection down use case that extend almost all use case, but I don't want to connect all with the notation on the use case diagram cause is very orrible to see. How can I do?

Answer 1

You can't - and it's nonsense. A use case shows added value for an actor. Extensions to use cases are very rare. In most cases people try to apply functional decomposition and mistake a step of actions recurring in multiple use cases as "partial" use cases. They aren't! If you are trying to do what you describe you went the wrong path. You should instead think why and where your use case synthesis broke.

I strongly recommend reading Bittner/Spence to get the right idea what use cases are all about.

Answer 2

First of all: the importance of Use Cases
Modeling Use Case Diagrams (Use Case Modeling) is SO important step in Software Analysis and Use Case Modeling should be performed by professional Analysts:

1. All estimations (Time, Budget, Resources and etc.) are performed based an Use Cases.
2. In some Use Case Driven Methodologies, all subsequent steps are based on Use Cases.
3. and etc.

Secondly: Knowing Use Case Modeling Traps.
In Use Case Modeling there are some traps that we need to conside related to your question:

1. (Trap #1: Use cases that users don't understand.) (see reference 1)

Use cases are a way to represent user requirements, which describe what the user needs to be able to do with the product. Use cases should focus on tasks a user needs to accomplish with the help of the system, so they should relate to the user's business processes. Your users should be able to read and review use cases to find possible problems, such as missing alternative flows or incorrectly handled exceptions. If users cannot relate to use cases, there's a problem. Perhaps they're written too much from a technical, rather than business, perspective.

2. (Trap #4: Describing specific user interface elements and actions) (see reference 1)

Write "essential" use cases that describe the interactions between the user and the system at an abstract level, without incorporating user interface specifics. The use case description should not include a screen design, although simple user interface prototypes can be valuable to facilitate the use case exploration.

3. (2. Not having clear business goals for every use case) (see reference 2)

4. (6. Specifying use cases in too much detail) (see reference 2)

Thirdly: Use Case Modeling is in the Requirement phage of methodologies.

We should not put common implementation methods in Use Cases. Common methods in implementation handled by other diagrams in next steps of methodology. (maybe in Design Model) So, if we put all common methods in Use Case Model, the number of use cases increases a lot. (and our estimation as mentioned in first part goes wrong)

Answer 3

You can use use inheritance.

Something like this, use cases B and C are extended since this is inherited.

But as @Kilian said, it would be interesting that you explain why you need a such model.