Amazon Kindle D00111 Manual do Utilizador descarregar pdf (Página 21)

4 Use Cases

4.1 Use Case Model

Use case is a system engineering approach that enables the system designer to show events as

seen from the user’s perspective. This first hand system information is both useful to the

engineer and the novices alike. Use cases if well done are used as binding agreement during

contract negotiation in many instances. The use case model is used here in this phase of the

project to portray the functional requirements of the system. Some aspects of the non-

functional requirement are also implicitly hidden in the functional requirements.

To achieve a comprehensive use case that covers all the functional requirements, one has to

start by identifying the actors (users) and all possible interaction between human and

machine. The actors in this system are the user of the E-Reader and the server while the

modules cover the Search, USB, WiFi, Camera, and Audio.

4.2 Flow of Events

Use case is a simple textual explanation of what the system does, it covers all the possible

ways of interaction between the user and the device, and in the same device, how different

modules talk to each other. This simple system engineering technique shows all the workflow

to a non-technical person normally the client, and the reason why it has to be in the text form

is that the client should have a better understanding of what he/she wants from the system.

In a simple scenario the basic flow of events show the interaction where a user enters a

continuous sequence of inputs and gets the desired feedback from the system each time. The

alternative flow would be the case, where the user cancels an ongoing process. In some other

scenario the alternative flow could be an exception handling.

Figure 4.1: Use Case Diagram

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 67 68

Sem comentários

Amazon Kindle D00111 Manual do Utilizador Página 21