Modeling system requirements with use cases.

Development focused on the user. System development process based on understanding the needs of those involved and the reasons why systems should be developed.

Modeling of use cases. Process of modeling the functions of a system in terms of business events, who initiated the events and how the system responds to these events.

The modeling of use cases provides the following benefits:

• Provides a tool to capture the functional requirements.

• Helps to break down the reach of the system into more manageable pieces.

• It provides a means of communication with users and with others involved in relation to the functionality of the system. The use cases present a common language that is easily understood by the different parties involved.

Concepts of systems in the modeling of use cases.

Diagram of use cases. It illustrates the interactions between the system and external systems and users. In other words, it describes graphically who is going to use the system and how the user expects to interact with the system.

Use cases.

These cases describe the functions of the system from the perspective of external users in a way and with a terminology that they understand.

Actors: Anything that needs to interact with the system to exchange information. They are classified as follows:

• Primary business actor: the interested party who benefits mainly from the execution of a use case when receiving something of measurable or observable value.

• Primary actor of the system: the person who has a direct interface with the system to initiate or cause the business or system event.

• External server actor: the person who responds to a request from the use case.

• Recipient external actor: the person involved who is not the primary actor but receives something of measurable or observable value.

Temporary event: System event that is activated by time.