> [!abstract] How is data inputted, moved, transformed in the system ![[gane-sarson-dfd-example.png]] ## Notes - Could be modeled by: [Gane & Sarson notation](https://online.visual-paradigm.com/knowledge/software-design/gane-sarson-dfd-tutorial) ## Logical vs Physical Data flow diagrams Data flow diagrams (DFDs) can be divided into logical and physical. The logical data flow diagram describes the flow of data through a system to perform certain functions of a business. The physical data flow diagram describes the implementation of the logical data flow. **Logical DFD** - Logical DFD depicts how the business operates. - The processes represent business activities. - The data stores represent the collection of data regardless of how the data are stored. - It’s how business controls. **Physical DFD** 1. Physical DFD depicts how the system will be implemented (or how the current system operates). 2. The processes represent the programs, program modules, and manual procedures. 3. The data stores represent the physical files and databases, manual files. 4. It shows controls for validating input data, for obtaining a record, for ensuring successful completion of a process, and for system security. ## Relates to [[Control Flow]] ## Sources [[Control Flow vs. Data Flow in Distributed Systems Integration]] [Gane-Sarson Data Flow Diagram Tutorial](https://online.visual-paradigm.com/knowledge/software-design/gane-sarson-dfd-tutorial)