Activity Diagrams

Flowcharts and their new incarnation, the UML activity diagram, have the advantage of reasonable familiarity : even people with no computer- related training or background know what a flowchart is. For example, a local newspaper recently published a flowchart that described an algorithm by which the brain processes the decisions involved in purchasing a Saab convertible . For reasons that are pretty clear, all paths through that particular flowchart ended up at the same activity: "Buy the Saab." There must have been a logic error in there somewhere, although we couldn't find it. But we sure are enjoying the car!

Figure 24-4 shows a typical activity diagram in UML notation. Although the same information could have been presented in pseudocode form, the UML notation provides a visual representation that may be easier to understand.

Figure 24-4. Example of an activity diagram

The problem with activity diagrams, as the technical computer community has learned over the past 30 years , is that they are a nuisance to keep up-to-date. Of course, it can be a nuisance to keep any visual representation of a requirement up-to-date without automated tools; nobody wants to redraw a state transition diagram or a decision tree, either.