In data flow modeling, which diagram shows the system boundary and external entities?

In data flow modeling, which diagram shows the system boundary and external entities?

• A. Context diagram
• B. Data dictionary
• C. Entity-relationship diagram
• D. Class diagram

Answer: (A)

In data flow modeling, the diagram that shows the system boundary and external entities is the context diagram. It presents the entire system as a single process and identifies all external actors or sources and sinks that interact with it, with data flows illustrating how information moves between the outside world and the system. The boundary is clear because what sits inside the single process is the system itself, while everything outside represents external entities. This view is high-level and doesn’t show internal processes or data stores, which come in more detailed diagrams later and are often labeled as Level 0 DFDs. Other diagram types serve different purposes: a data dictionary documents data elements and their attributes, an entity-relationship diagram maps data entities and their relationships, and a class diagram models classes and their interactions in an object-oriented design. None of these focus on the system boundary and external actors in the way the context diagram does.

In data flow modeling, the diagram that shows the system boundary and external entities is the context diagram. It presents the entire system as a single process and identifies all external actors or sources and sinks that interact with it, with data flows illustrating how information moves between the outside world and the system. The boundary is clear because what sits inside the single process is the system itself, while everything outside represents external entities. This view is high-level and doesn’t show internal processes or data stores, which come in more detailed diagrams later and are often labeled as Level 0 DFDs.

Other diagram types serve different purposes: a data dictionary documents data elements and their attributes, an entity-relationship diagram maps data entities and their relationships, and a class diagram models classes and their interactions in an object-oriented design. None of these focus on the system boundary and external actors in the way the context diagram does.