Fragmento do livro de peter

Chapter 4 – Conceptual Design: System Purpose, Actors, Features and UML Use Cases

CHAPTER OBJECTIVES (YOU SHOULD BE ABLE TO):

1. Define and give examples of the purpose of an information system.
2. Describe and give examples of actors.
3. Describe and give examples of features in an information system.
4. Define the UML Use Case notation and be able to draw a use case diagram.

Getting started! For many people, these two words represent an enormous hurdle or mountain to climb over. That term paper! That big test to study for! The whole apartment needs cleaning! Writing all those "thank you" letters! Many projects seem overwhelming as we think about just getting started. Getting started with the technical/engineering aspects an information systems development project can also be difficult because there are so many ways in which one could actually begin a project—for this discussion we are omitting the project management aspects associated with starting and keeping track of an information systems project status. You may recall that a few "ways to get started on an information systems development project" was discussed in Chapter 2 as part of the requirements determination discussion. In that chapter three dominant problem-solving strategies were identified—function, data, and object. To review briefly, the functional problem-solving strategy approaches a problem by first identifying the actions the system must accomplish, such as "register for a course", "drop a course", "check out a movie video", and so on. The data problem-solving strategy approaches a problem by first identifying the data that the system is responsible for, such as "student information", "course information", "schedule information", "movie video information", and so on. Finally, the object problem-solving strategy approaches a problem by simultaneously focusing on objects, such as people, places, things and concepts and the object's attributes (data) and operations (services). For