MSc-IT Study Material
January 2011 Edition

Computer Science Department, University of Cape Town
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The different kinds (and levels) of data-flow diagrams

Although all data-flow diagrams are composed of the same types of symbols, and the validation rules are the same for all DFDs, there are three main types of data-flow diagram:

During this unit we shall investigate each of the three types of diagram in the sequence they are described above. This is both a sequence of increasing complexity and sophistication, and also the sequence of DFDs that is usually followed when modeling systems.

For each type of diagram we shall first investigate what the features of the diagram are, then we shall investigate how to create that type of diagram. However, before looking at particular kinds of data-flow diagrams, we shall briefly examine each of the symbols from which DFDs are composed.