Physical DFD to Logical DFD
How to Derive Logical DFD from Physical DFD? Physical DFDs are a means to an end, not an end in themselves. They are drawn to describe an implementation of the existing system for two reasons: · to ensure a correct understanding of the current implementation (users are generally better able to discuss the physical system as they know it through people, workstations and days of the week.) · the implementation itself may be a problem or limiting factor; changing the implementation, rather than the system concept may provide the desired results. A logical view steps back from the actual implementation and provides a basis for examining the combination of processes, data flows, data stores, inputs and outputs without concern for the physical devices, people or control issues that characterise the implementation. A logical data flow diagram is derived from the physical version by doing the following: · Show actual data needed in a process, not the...