A data-flow diagram ( DFD ) is a graphical representation of the "flow" of data through an information system. DFDs can also be used for the visualization of data processing ( structured design ). On a DFD , data items flow from an external data source or an internal data store to an internal data store or an external data sink, via an internal process . A DFD provides no information about the timing or ordering of processes, or about whether processes will operate in sequence or in parallel. It is therefore quite different from a flowchart, which shows the flow of control through an algorithm, allowing a reader to determine what operations will be performed, in what order, and under what circumstances, but not what kinds of data will be input to and output from the system, nor where the data will come from and go to, nor where the data will be stored (all of which are shown on a DFD ). ...
Points worth noting. I was doing some studies on Data Flow Diagram recently and was writing an article about it, but I did not noticed that this important information was missing. Thank you very much for this post.
ReplyDeleteDear Suresh Khanal,
ReplyDeleteIf you go through a Kendall and Kendall's Book it shows Context Level and Zero "0" Level as a different level DFD. According to Book by James A. Senn Both are same.
So, Whatever method you follow just mention the reference you have taken from that book.
From my point of view James A. Senn's book have clear and Correct approach toward DFD.