What is use case diagram?

What is a use case diagram (UML)?

Why Use case diagram? or simply, Why use cases?

A UML use case diagram is the primary form of system/software requirements for a new software program underdeveloped. Use cases specify the expected behavior (what), and not the exact method of making it happen (how). Use cases once specified can be denoted both textual and visual representation (i.e. use case diagram). A key concept of use case modeling is that it helps us design a system from the end user’s perspective. It is an effective technique for communicating system behavior in the user’s terms by specifying all externally visible system behavior.

A use case diagram is:

• Summary of the relationships between use cases, actors and systems.

A use case diagram is not:

• A presentation of the order in which steps are performed to achieve the goals of each use case.

As said, a use case diagram should be simple and contains only a few shapes. If yours contain more than 20 use cases, you are probably misusing use case diagram.

Free use case diagram books

Listed below is a rich collection of free UML eBooks related to UML use case diagrams. If you want to learn more about use case diagrams or UML, we recommend you to have a look.

More UML books and UML tools

Want to learn more about UML? We have a rich collection of UML books, UML lectures and UML presentations. Check for more details.

If you want to draw UML diagrams, we recommend you try out the UML tools below:

• Visual Paradigm (Desktop) – Award-winning UML modeling software
• Visual Paradigm Online – Easy-to-use UML diagram tool

Enjoy! 🙂