Description

We can define the primary actors in any Use-Case as the actor (s) using the system to

achieve a goal. The use case documents the interactions between the system and the

actors to achieve the purpose of the primary actor. Another actor’s aid system needs to

achieve the goal of the primary actors Primary Actor in a Use-Case used for calls on the

system to deliver service. We can draw the primary actor in use by using a software that is

used for design the use cases such as visio, we can draw by using just drag and drop

method. In use case the primary actor is takes place outside the subsystem. We can draw

same actor in DFD diagram as an entity of the diagram.

2. The main relationship between level 0 and level 1 we can define as level 0 DFD show all

processes (and external bodies), while level 1 DFD shows the sub-process and free of

external entities (for small systems). For example, the process of the fifth level 0 DFD

can be divided into sub-process 5.1, 5.2, 5.3, 5.4. Cite steps in Building DFDs hierarchy

are given below: