Software design documentation with UML

First of all, you don't really need all of the various diagrams to document a design. Instead, start with the most useful diagrams first.

For example, for an embedded control application, I developed simple class diagrams to describe the static software structure, and a set of statecharts to describe the dynamic behavior of the system. As the project design progressed, I added other types of diagrams as needed to describe or explain design issues.

I tend to use the other diagrams as needed, but only when they provide real value in describing how a system is organized or how it runs. Simply drawing all of them to fill a square is a waste of time.

By the way, if you do produce a lot of different types of diagrams using drawing or design software (I use Canvas), then try to get a big inkjet drafting plotter for printing them. The diagrams are easier to draw and use on an 'E' sized engineering drawing instead of on a bunch of 8 1/2 by 11 pages.

Hope this helps...

clarkmk's reply is about what I do, if required. An easier way is to use a round-trip CASE tool like Together (togethersoft.com) or Rose (rational.com) on the source files: it reads the code and creates the implementation-level UML diagrams that match the code.

When going the other way, I use the tool to generate code from the diagrams. I like to start coding with the class diagrams, adding other diagrams when they're useful.