Creating a Use Case Diagram
A use case diagram is used to describe the interactions between the organization actors and the system, for each of the planned use cases.
A use case is a sequence of actions that produces an observable result for a particular actor. Scenarios illustrate use case examples.
These use cases are grouped into packages representing the system boundaries.
A package partitions the domain and the associated work. It is used to organize elements into groups, particularly use cases and classes. Packages may be nested within other packages. Packages are linked by contractual relationships that define their interface.
The package is the element from which you will create the use case diagram. However, for complex systems, you can also create this type of diagram from a use case in order to detail the latter.
Creating a Package
To create a package:
1. Open the Main Objects navigation window.
2. Right-click the Packages folder and select New Package.
The Creation of Package dialog box appears.
3. Enter its Name.
4. Indicate the library and owner package if necessary.
The default library is used to store an object if there is no current library at the time of its creation.
5. Click OK.
The package is created and added to the list of packages.
When the
OK or
Create buttons are grayed, this is because the requirements for the dialog box in which they appear have not been completed.
Creating the Use Case Diagram of a Package
To create a use case diagram:
1. Right-click the package concerned.
2. Select New Diagram.
A dialog box opens indicating possible diagram types.
3. Select Use Case Diagram.
4. Check that the Diagram initialization check box is selected.
The
Diagram initialization option takes account of the object environment in the drawing.
5. Click Create.
The diagram opens in the MEGA Edit window. The frame of the package is positioned within the drawing.