Use Case Diagrams

man-using-computerHi people, this blog is going to discuss about diagrams that we use for Data modeling. This first article will be helpful to draw a Use case diagram correctly. In this tutorial we will learn about:-

  • What is a use case diagram?
  • Rules that we use.
  • Relationships in a use case diagram.
  • Example diagram.

What is a use case diagram?

  • It is a graphical diagram that shows activities and interactions among elements of a system.
  • The use cases, which are the specific roles played by the actors within and around the system.
  • A use case diagram has set of components which are :
    • Use case (mostly functionalities of the system)
    • An actor (people or other systems)
    • System boundary
    • Associations (relationship types)

1

  • Simply we can get an idea about how is the system work, by looking at the use case diagram.

 Rules that we use

  • We use simple present tense for use case’s name.

Ex:- register student, transfer money

  • Actors must be nouns.

Ex:- client, supervisor

  • Actors are not always living things.

Relationships in a use case diagram

  1. Simple association

2

  • We use solid line in this type of relationships.
  1. Generalization & Specialization

3

  • Generalization:-
  • Specialization:-
  • We use solid line arrow with close empty arrow head in this type of relationships.
  1. Use case generalization

4

  • We use solid line arrow with close empty arrow head in this type of relationships.
  1. Include relationship

5

  • Every time when perform A, B must be performed.
  • We use dash line arrow with open arrow head in this type of relationships.
  1. Extend relationship

6

  • Every time when we perform A there is an option to perform B.
  • We use dash line arrow with open arrow head in this type of relationships.

Example diagram

Scenario 1

Click here to download the PDF file.

Use case

7

Scenario 2

Click here to download the PDF file.

Use case

8

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s