Bob Lambert

Jazz on the harmonica

Free form diagrams part 3: just right, with a few rules


Free form diagramming doesn’t only mean “no rules”, it also means “just right”.

This post, last in a three part series on free form diagramming, gives some simple guidelines for getting the technique right.  Part one talked about the tension between rigor and expression in diagramming for analysis and design, and how more precise diagrams can hinder rather than help communications with business people.  Part two reviewed free form diagramming in practice.

While it is impossible to specify format and structure of a free form diagram in advance, here are some useful guidelines to follow when building your free form diagram:

•    Rule number one: draw it as you see it. Typically, an analyst uses a free form diagram because he/she already pictures a business process.  Trust your mental picture and get it down on the page.  Then, go through the following checklist to make sure it says what you want it to say.

•    Model real world processes, things, and events. Free form diagrams have one great advantage over Use Case Diagrams, Data Flow Diagrams, and the rest: they are concrete rather than abstract.  For example, in a free form diagram you can symbolize a shopper with a clipart picture of someone choosing a soup can from a grocery store shelf.  The free form diagram should clearly represent things from the real world: organizations, locations, business processes, interfaces, etc.

•    Use symbols consistently. Look at each repeated rectangle, line, circle, icon, etc, and verify that everything with the same shape represents the same type of thing or event.

•    Speak the language of the audience. A free form diagram should depict things business people care about in recognizable terms.  For example, accountants might readily understand boxes labeled GL, AP and AR for general ledger, accounts payable, and accounts receivable.  A shipping clerk might quickly interpret a process illustration showing labeled icons shaped like trucks and warehouses.

•    Arrangement on the page conveys meaning. Frequently, free form diagrams group objects that belong together on the page.  In other cases, the diagram shows a definite process flow by the arrangement of objects.  For example, Business Intelligence Architecture diagrams typically show information flow from source systems on the left to business reporting on the right.  Could this kind of flow or grouping improve your diagram?

•    Limit the number and complexity of objects on the diagram. Most often, a meaningful diagram shows relatively few objects, organizes them in a sensible way, and does not cross lines.  If you need many objects to tell the story, reduce complexity by arranging them logically.

•    Work at one level of detail, or clearly indicate differences between levels of detail. If your diagram includes a box labeled “AP System” then it would not likely make sense for it also to contain another labeled “Journal Voucher Key”.  Diagrams that communicate well are all at the same level of detail or clearly indicate differences in level of detail.

The free form diagram can be an essential part of a successful IT application project by enabling all to understand the target system in the same way and helping business people understand critical functionality.




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