Data Flow Diagram |
Data flow diagrams are useful in modeling high-level systems and processes. These diagrams show the way in which data flows between elements in a system and between the system and external entities.
Typically, several data flow diagrams are used to understand a problem. The top-level diagram is called a context diagram and contains one Functional Transform which represents the entire system. The context diagram also shows the external entities that interact with the system. The following context diagram shows an order entry system that interacts with customers and shippers. The solid lines represent the flow of data.
The functional transform "Order Entry System" represents all of the logical processes of the system. This is then exploded or "decomposed" into a more detailed data flow diagram which itself will contain one or more functional transforms which in turn can also be decomposed. Decomposition can continue to arbitrary depth.
To decompose a Functional Transform select Explode Into from its right-click menu.
Data flow diagrams in Visual Case can model the flow of control as well as the flow of data. Use the right-click menu to show or hide the Control Transforms and Control Flows on your diagram. A Control Transform can be decomposed into a State Diagram. Together, the state diagram and control transform model the dynamic aspects of the system.