Basic Use Case Model

The Basic Use Case Model pattern creates elements and a Use Case diagrams that describes the goals that user roles wish to achieve from the system. The Use Cases are all contained within the System Boundary and the Actors all lie outside the Boundary.

Figure 1. Shows a Use Case diagram with Actors and a number of Use Cases enclosed in a System Boundary. One actor represents a system and used the rectangular notation.
Discussion
The purpose is to allow Business Analysts and other stakeholders to describe the value that Actors (the roles that users play) want to achieve when interacting with the system.  

The pattern is typically used in the analysis phase of an initiative and can be used to realize any number of Requirements and as a way of providing specification for the implementation team.

The following is a list of some things you may want to do when working with this pattern.
·	Change the name of the System Boundary to suit the initiative.
Change the name of the Actors and Use Cases to suit the initiative.
Add descriptions to describe the value the Use Case offers.

The following is a list of some of the next steps available when applying the pattern.
·	Use the Scenario Builder to define the detailed steps in one or more Use Cases.
Generate a behavioral diagram that describes the detailed steps visually.
Create trace relationships between the Use Case and Requirements.
Create Realization relationships between the Use Case and Components that implement them.
Structure the Use Case Model using Extend, Include and Generalization relationships.

Useful Workspace Layouts Design | Use Case Modeling, Requirements
Reference
The following help topics will assist you learn about how to work with this pattern.
Use Case Diagram
System Boundary
Use Case
Actor

The following are some of the tools that will be helpful when working with this pattern.
Scenario Builder
The Scenario Builder is a productive and unique tool and editor that allows the analyst to work with the text of Use Cases and Scenarios directly inside the model. Many analysts will be familiar with creating long and voluminous Word Processor documents describing the details of Use Cases. With the Scenario Builder the descriptions and steps of Scenarios can be entered directly into the repository and linked to other elements. Alternate and Exception paths can be defined including branch and re-entry points. Diagrams representing the steps in a scenario can be generated and automatically synchronized. For more details see the Scenario Builder help topic.
Traceability Window
The Traceability Window automatically displays the relationships that exist between Use Cases and other model elements including up-process and down-process elements. The traceability tree view can be conveniently expanded to see deeper relationships and elements displayed in the window can be located in all diagrams in which they appear. For more details see the Traceability Window  help topic.
Document Generator
The Document Generator is a powerful facility in Enterprise Architect that allows a Database Engineer or other stakeholder to create high quality corporate or technical documentation directly from the model, suitable for internal or external audiences. For more details see the Documentation help topic or the more general topic on Model Publishing.
Specification View
The Specification View can be used as a way of working with the Components and Interfaces particularly when there are a large number of elements as is typically the case when describing a system of any appreciable size. For more details see the Specification View help topic
Relationship Matrix
The Relationship Matrix provides a spreadsheet like view of two groups of elements and the relationships that exist between them. It can be a used as a powerful analysis mechanism to visually indicate how elements are related to each other and to discover which elements are missing relationships. For more details see the Relationship Matrix help topic.

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