Data flow diagrams or DFDs help the analysis of systems by showing:
- Data sources
- What processing happens and by whom
- Who uses the data
- Where data is stored and when
- Outputs produced
The different levels of Data Flow DiagramRepresenting the complete business system often requires multiple levels of diagram.
Context Diagram (Level 0 DFD)This is the highest level of a DFD and provides a very abstract, high-level view of the system. The entire system is represented as a single process, with arrows indicating the data flow into and out of the system from external entities. It serves as a broad overview of the system and its interaction with external factors. This diagram is particularly useful for providing stakeholders with a rudimentary understanding of the system.
Level 1 DFDThis diagram breaks down the system from the Context Diagram into its major, high-level process components. Each component is represented as a process in this DFD. Level 1 DFD shows how the system is divided into sub-systems (processes), illustrating the flow of information from and to each of these sub-systems and how they interact with each other. As per the convention, it should typically describe the system using between two and seven functions.
[Level 1 Data Flow Diagram -] this highlights the main functions carried out by the system. As a rule, we try to describe the system using between two and seven functions. SQA
Level 2 DFDIf necessary, each of the high-level processes of the Level 1 DFD can be further broken down into their lower-level processes in the Level 2 DFD. This allows for a more detailed representation and understanding of the system's functioning. Each of these processes can be further divided into even lower levels until sufficient detail is achieved.
Level n DFDTheoretically, this decomposition can continue for several levels. Each level adds more details and complexity to the system's description.
Example Data Flow DiagramThis example of a level 1 data flow diagrams is free to copy, download and use. Don't have Visio?
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Other example data flow diagrams
Data Flow Diagram - referenceshttps://whatsupnew.com/wp-content/uploads/image3.gif