Process modeling is intended to track the inputs, process and outputs of each discrete function in our application. The analysis is intended to ensure that the process has all of the inputs it needs, and that the rules used by the process to generate the output are defined. Data does not magically move about but must be delivered. This prevents the overview model from being displaying overwhelming detail, but the user can drill down to see the details of a process when needed. It also seeks to evaluate the worth of any output.
Transactions are processes that complete a single business function.
They should not be separated such that the inputs can change or outputs be used during the transaction process. Workflow analysis attempts to manage a single instance of the process being used to accomplish a business function. It is a reaction to the fact that many instances may be in existence at any one time in various stages of completion. The DFD is considered a workflow tool. The flow must be automated in order to trigger the next required process.