uml

Summary: Notes on using Visio for UML diagrams (mostly why I don't like to use Visio).

I think it is okay to use Visio for UML diagrams when you're not going to be doing very many, especially if you already own a copy of Visio. But once the application you're modeling gets to be substantial at all, Visio has a major flaw:

You're trying to model a software application that has a data model with a drawing program.

To me, that's not a very good idea.

Note: Amazingly, I wrote this review way back in 2007. I just tried to use Poseidon UML again in 2010, and I wouldn't change a word of it. (Okay, I'll change one thing: I now use UMLet instead of MagicDraw UML.)

I don't know if you've ever had UML use case burnout, but I think I just hit the wall. Here's a link to some use case prose that shows I've written way too many use cases recently.

Maybe this is a good way to know when you need a vacation?

Question: I want to show how my application classes are segregated into packages. Is there a UML diagram for this?

Yes, you pretty much named it. A UML package diagram is good for demonstrating the packages (or packaging) in a software application, as well as the dependencies between packages.

Question: I want to look at the relationships between the classes in my software application. What UML diagram should I use?

UML Class diagrams are very good for showing the static relationships between classes, such as inheritance and aggregation, one to many relationships, and many other class relationship details.

Question: What UML diagram can I use to show how my application will be distributed in the real world?

Use a UML deployment diagram. They can be used to conceptually show the physical nodes and software components that will be distributed in a software application.

Question: What UML diagram can I use to show how an object state changes during its lifetime?

A UML state diagram will do the trick. A state diagram is very good for showing how an object state changes over the lifetime of a software application, and the triggers (triggering events) that cause the state to be changed.

Need to show how objects collaborate during the lifetime of a software application? You'll want to use a UML interaction diagram -- either a sequence diagram or a collaboration diagram.

I prefer the sequence diagram, because the time sequence of events it displays more easily demonstrates the interaction of objects over time, but other developers prefer collaboration diagrams.

Question: I want to visually model a multi-threaded software application. Can UML help?

Yes, UML activity diagrams can be a great tool for visually modeling the flow of control in a multi-threaded application. A UML state diagram can also be used to show the states objects can be in during their lifetimes.

I've been working on a document for one of my customers named "Use Case Best Practices", but then I decided to search the Internet to see if I could find anything similar to what I was thinking.

The best thing I've found is this Coad Letter on Borland's web site. There is enough meat here that I'm scrapping my plans and just suggesting they read that document instead. Kudos.