They set the coursework at the university - building a code for DFD (Data Flow Diagram or data flow diagram). Having studied the subject area (in particular, here ), I came to the conclusion that diagrams of this type are logical diagrams that only model the area of data streams. That is, to transfer this further, you need to build other diagrams, for example, UML, where you can already display areas marked on the DFD diagram.
Actually, the question is: tell me how wrong I am, and how they are doing it right, and also - is it possible (and is it actually being done that way) to build code using a DFD diagram? If yes, then you can sample software, or algorithm, whatever. Thank.