Data Flow Diagrams 3.0

  • Do you start with a context diagram?
  • What’s a multi-process, and when should I use one?
  • Do I really need to draw single-headed arrows? They make my diagram hard to read!
  • Is this process inside this arc? Is an arc the best way to show a trust boundary?
  • Should I color things?
  1. It uses 5 symbols. A rectangle represents an external entity, a person or code outside your control. A rounded rectangle represents a process. They’re connected by arrows, which can be single or double headed. Data stores are represented by parallel lines. A trust boundary is a closed shape, usually a box. All lines are solid, except those used for trust boundaries, which are dashed or dotted. (There is no “multi-process” symbol in DFD3.)
  2. It must not* depend on the use of color, but can use color for additional information.
  3. All elements should have a label.
  4. You may have a context diagram if the system is complex. One is not required.

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Adam Shostack

Adam Shostack

Generally blogging at adam.shostack.org/blog, but shared posts here before Medium asked me to jump through more and more hoops..