Sonar is SO cool!

Do you know Maven? Then you know the project site that can be easily generated with Maven. For instance, look at the site for the Tomcat Maven plugin. It provides information on using the plugin, project related information and – probably most importantly for most "normal" (i.e. non-plugin) projects – the project reports.

You can easily configure Maven to execute a number of useful reports like JavaDoc, Checkstyle, PMD (coding rule verification), CPD (duplicate code detection), and JUnit test coverage. Additionally, you can install custom reports to also participate in project site.

This is great, but still lacks some features:

• What if you would like to see overall code quality, without having to consult several detailed reports? Just a single, combined indicator?


• With the reports, it's not always easy to drill down a particular issue up to source code level.


• It would be nice to be able to access historic versions and compare quality between them to early recognize trends, wouldn't it?

All this (and more) is provided by Sonar (http://sonar.codehaus.org/), an open source tool that "enables to collect, analyze and report metrics on source code. Sonar not only offers consolidated reporting on and across projects throughout time, but it becomes the central place to manage code quality."

Sonar collects data provided by well-known Maven reports, stores them into a database, and provides a modern, fast and convenient user interface to browse the projects and quality metrics, and to drill down from project to Java code level.

Just look at the screenshot of an internal test project... how cool is that?



Installation is as simple as it can be. You can use Sonar with provided Jetty or install it in your existing container. For production, you can switch from embedded Derby database to a "real" database (like MySQL, Oracle, SqlServer, ...). Of course, you can adjust the rules to be checked or import your existing configuration (for Checkstyle or PMD).

To send data to Sonar, you just execute a Maven command to call a particular sonar-maven-plugin for your project:

mvn clean install org.codehaus.sonar:sonar-maven-plugin:1.6:sonar

That's it... now watch all the magic going on.

This Maven goal can be called manually, but is best integrated with nightly builds. To further simplify this, there is a Sonar plugin for Hudson, my favorite continuous integration engine. Using this nice plugin, configuration of a Job to connect to Sonar is as simple as clicking a checkbox in post-build section!

Sonar is so great I really wonder why I didn't find this tool earlier – current version is 1.6, so it must have been out for a while... You definitely should give it a try!