Agile Architecture Deck & Code

Here’s my Agile Architecture - Patterns & Technology slide deck (bottom of this post) that I presented at SpringOne2GX and OOPSLA. Thank you to all who attended, and for providing such positive feedback. I’ve also uploaded the code samples used to show the modularity pattern examples found toward the end of the presentation. The code can be found under the billpayevolution project in my Google code repository.

A Bit More on the Code

The project is named billpay, and is a very simple system. It starts out in life as a project that’s bundled and deployed using a single WAR file (InitialVersion). Through a number of refactorings (7 in total), the project is broken out into separate modules, and the final version of the system (Refactoring7ImplementationFactory) has a number of modules (JAR files) that are included in the WEB-INF/lib of the WAR.

I intentionally avoided using OSGi for this exercise, primarily to show how we can modularize an application without a runtime module system. I do have an OSGi version of the system that can be deployed to an OSGi runtime (Tomcat using the Equinox Servlet Bridge is what I used), but I haven’t uploaded that code to the repository yet because I have a few things I need to change (like using Spring DM to remove the code dependencies on the OSGi API). That’ll come later, after I’ve had a chance to do a bit more work with it.

Each project along the path toward refactoring the application into modules comes with it’s own build script. For each project, except for the final version (Refactoring7ImplementationFactory), all you’ll need to execute the build is Ant and JUnit.

A Note on JarAnalyzer

Because I used JarAnalyzer in the final refactoring, you’ll need to make sure you have GraphViz installed and then modify the build script to point to the dot executable. Of course, you can also comment out the JarAnalyzer target, too. But JarAnalyzer was very helpful in identifying and managing the dependencies between modules, so I think you’ll find it useful to keep it. If you’re not familar with JarAnalyzer, it produces visual output showing the dependencies among JAR files (shown at right, click to enlarge), as well as an HTML report with some of the Martin metrics. Here’s the JarAnalyzer HTML report for the final version of billpay.

Like with any project, there are a few things I’d like to change. For example, in Refactoring7ImplementationFactory, I’d like to use Spring to inject the implementation classes instead of using the factory. Sometime soon, I hope to walk through these samples in a series of blog entries that shows how modularity can have an amazingly positive influence on the architecture of a software system. Until I do this, or you attend one of my presentations (btw, I’m speaking next week at Agile Development Practices), it may be a tad difficult to understand the forces behind my decisions (hint: they were driven by various business requirements). So please be patient, and stay tuned.

And Now the Presentation

Here’s the presentation, hosted on SlideShare. I look forward to your questions and/or any feedback you might have!

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