 Need to Gather requirements and other related information  Use case Modeling ◦ What the system will do for the users

 A client makes a call that is taken by the operator, who determines the nature of the problem. Some calls can be answered immediately, other calls require research and a return call.

 The process consists of the following steps:  1. Identify the actors: ◦ Who is using the system? ◦ Or, in the case of a new system, who will be using the system?  How would such information be gathered?  2. Identify the requirements (use cases) which the system must support.

 The use-case model describes the uses of the system and shows the courses of events that can be performed.  Use case defines what happens in the system when a use case is performed. ◦ Model ◦ Description  The use-case model tries to systematically identify uses of the system and therefore the system's responsibilities.

 Use cases are scenarios for understanding system requirements.  A use case is an interaction between users and a system.  The use-case model captures the goal of the user and the responsibility of the system to its users.

 The description of a use case defines what happens in the system when the use case is performed.  In essence, the use-case model defines the outside (actors) and inside (use case) of the system's behavior.  A good starting point for: ◦ Designing the GUI (prototype) ◦ Testing the system

 The term actor represents the role a user plays with respect to the system.  When dealing with actors, it is important to think about roles rather than people or job titles.

 Candidates for actors can be found through the answers to the following questions: ◦ Who is using the system? Or, ◦ Who is affected by the system? Or, ◦ Which groups need help from the system to perform a task?

◦ Who affects the system? ◦ Which user groups are needed by the system to perform its functions? These functions can be both main functions and secondary functions, such as administration. ◦ Which external hardware or other systems (if any) use the system to perform tasks?

◦ What problems does this application solve (that is, for whom)? ◦ And, finally, how do users use the system (use case)? What are they doing with the system?

 These relationships are shown in a use-case diagram: ◦ Communication. ◦ Uses. ◦ Extends.

 The use association occurs when you are describing your use cases and notice that some of them have common subflows.  The use association allows you to extract the common subflow and make it a use case of its own.

 The extends association is used when you have one use case that is similar to another use case but does a bit more or  Is more specialized; in essence, it is like a subclass.