techblog 

In the recent Jolt Awards you may (or may not) have noticed an award to Structure101 by Headway Software. We’ve been using this tool for a while now and I thought it might be worth giving my impressions. Put simply it allows you to visualise the dependencies within your Java codebase and highlights areas of complexity. It does this using a concept called ‘Excess Complexity’ which Headway Software explain on their website. It shows this complexity at every granularity from top-level package right down to method.

Obviously decisions about this sort of thing can never be entirely automated, but this tool does give you a good way to track down design ‘smells‘ in the code. It may be that the complexity is not a problem, but it certainly gives you cause to reconsider your design decisions in that area.

You may be thinking at this point “But my IDE already shows dependencies, so why would I need to pay good money for this?”. That may be true and I know for a fact that IntelliJ IDEA at least will display a grid of package dependencies for you. But if you decide that you want to unpick some circular dependencies it is very hard to see what’s causing the problem. Compare:

I know which of these is more intuitive. The Structure101 diagram also has the advantage that clicking on the links show exactly which piece of code is causing the dependency.

At the moment we are using the tool to keep our dependencies under control by just analyzing them and graphing the overall complexity figure on a whiteboard. This helps to motivate you to keep it down. We will be fully integrating it with our continuous integration server when we move over to a new system in the next week or so. After that we may consider using the IDE plugins to highlight design problems to individual developers as they work.

Overall, a nice piece of work to keep control of complexity and one that is now free for open source projects.