Software Engineering - Old Questions

System modeling is the process of developing abstract models of a system, with each model presenting a different view or perspective of that system. It is about representing a system using some kind of graphical notation, such as Unified Modeling Language (UML). Models help the analyst to understand the functionality of the system; they are used to communicate with customers.

Models can explain the system from different perspectives:

• An external perspective, where we model the context or environment of the system.
• An interaction perspective, where we model the interactions between a system and its environment, or between the components of a system.
• A structural perspective, where we model the organization of a system or the structure of the data that is processed by the system.
• A behavioral perspective, where we model the dynamic behavior of the system and how it responds to events.

Five types of UML diagrams that are the most useful for system modeling:

• Activity diagrams, which show the activities involved in a process or in data processing.
• Use case diagrams, which show the interactions between a system and its environment.
• Sequence diagrams, which show interactions between actors and the system and between system components.
• Class diagrams, which show the object classes in the system and the associations between these classes.
• State diagrams, which show how the system reacts to internal and external events.