With Sonar's project dashboard, you gain quick access to and insight about all your projects through a comprehensive dashboard. The dashboard presents vital quality metrics in an efficient way, highlights sections which require your attention, and finally includes common interface practicalities, such as sorting, adding, or removing columns to make browsing easier. The majority of the user interface is implemented in AJAX and the transitions between the different views and drilldowns are quick and smooth. Likewise, the components of the platform from simple to more complex ones are very responsive and react in a timely fashion to your actions.

The dashboard is fully customizable, and you can select which metric columns each view contains and reorder them as you like. The ability to internationalize the platform is a huge plus allowing you to present a total solution covering every aspect, from pleasant and practical interface to language settings. Generally speaking, language friendliness is very much welcomed if you intend to provide a Sonar instance to a less-technical audience.

If you want to take look at the Sonar dashboard in full swing, point your browser at Nemo, a Sonar demo instance by SonarSource S.A. hosting the platform's own source code among other well-known open source projects at http://nemo.sonarsource.org.

More than 600 rules are incorporated into Sonar, performing simple checks to complex calculations. Rules can be fully parameterized to meet different development needs, and if this is not enough, with a little help from the lively community, you can even implement your own, covering every possible need.

The strictest Sonar profile includes about 720 rules, but probably you won't ever need to activate it. It is not even suggested to use all of them at all. The objective is to provide as many coding rules as possible and let the developer make choices accordingly, assigning them to custom profiles for projects. Obviously, there is the ability to host multiple different profiles with specific sets of rules and further assign these profiles to different projects for maximum flexibility.

Metrics are necessary to form objective and reliable opinion on any piece of software. Like in every science or process, metrics are essential to measure and reproduce behavior and functionality, and help evaluate/compare source code, establishing a common ground among different pieces of software. In other words, metrics form a common denominator for all software and they have become an integral part of the development process.

One use for software metrics, which does not have to do directly with quality is that they can also provide insight and deeper knowledge about the source code, revealing potential pitfalls, and providing a safe guideline for new developers to follow. Sonar includes all classical metrics related to software development, some of them being:

If you have at least a couple of development years under your belt at some time or another, you have probably wondered how you could ever manage without writing any tests for your code. Untested software results in an unstable product, not working as expected. Experience shows that the first thing the end user does with an untested feature ends up to be unexpected and never taken into consideration during development. Random input, experimenting, or using the feature/component for something other than what it was designed for, are all viable and very real cases. While clients demand dynamic help systems and comprehensive manuals, they never ever read them, expecting the software to meet their expectations one way or another.

Software testing verifies that a feature will work as expected and meets design requirements. However, writing tests for the sake of testing only to cheat the metrics, covering low-risk code, and leaving out crucial areas, is pointless. This kind of testing, while it consumes time and resources, adds nothing to the final quality of your product.

Sonar identifies high-risk software pieces and locates untested code not only at line, but even at branch level, taking into consideration all possible outcomes of a conditional operation. Additionally, Sonar provides useful statistics concerning test successes and total duration.

Knowing where quality suffers and what aspects of your software need to be strengthened is one thing, specifically locating these problematic areas is another. Sonar features smart components as the metrics radiator that in combination with the dashboard allow you to drill down effortlessly to your source code reaching classes that require attention quickly. It may sound like a complex investigative task or an alternative search tool for your source code but this is not the case.

Drill down is a standard professional method used to browse code. You set a focal point, undocumented code for example, and move downwards from summary information to more detailed data, subsequently exploring modules, packages, and classes.

Sonar stores all analysis results in a database, preserving historical data for future reference and comparison, enabling you to track the evolution of your code. At any time you can check out a past version of your codebase from the repository and add it to the project's time line for comparison. Examining a data point in isolation can enlighten your team about the state of the code in the given time frame, but the information accumulated by the historical data proves to be invaluable in the long run, helping to determine the best approach for the health of your project.

You can examine the progress of your code using one of the three different components available: the Time Machine, the Motion Chart, and the Timeline. Each component can be dynamically customized to access historical data on all metrics supported. The Motion Chart, the fanciest of the components, features an animated bubble chart tracking metrics in four different dimensions: the X and Y axes, plus the color and size of the bubbles.

Maven is a build automation tool like Ant, streamlining the steps of the build process in software development. Checking out code, compiling, generating documentation and reports, running tests, producing artifacts, and finally deploying them, are some of the goals supported by Maven and implemented via plugins. Different profiles described in XML configuration files dictate the execution steps that take place during the build process while providing configuration details.

The Sonar platform takes advantage of the Maven goal-oriented philosophy, simplifying configuration. All you have to do is add the Sonar Maven Plugin into your project to get support for Sonar-oriented goals. The only requirement is to have the Sonar server up whenever the goal is executed. Basically, the setup requires zero or minimal configuration if you are familiar with Maven.

Much thought and work has been put into the platform's user interface in regards to both appearance and behavior. The clean interface is mostly self-explanatory but if you have any queries or feel like clarifying some things more, there is plenty of documentation and media available within the Sonar community covering many topics, from traditional getting started wikis to screencasts exploring advanced Sonar features. It is important to note here the web nature of the user interface, accessible straight from your browser.

Sonar introduces a new paradigm on measuring quality without trying to reinvent the wheel in the field of metrics and rules. While it features its own implemented set of rules, under the hood most work is handled by familiar and long-trusted tools. Sonar unifies these tools, leveraging existing functionality, collecting output, and finally refining the results to follow suit with the platform's objective.

As SonarSource puts it:

Obviously, the procedure of running these tools manually in sequence to produce raw values and statistics is now rendered obsolete, since Sonar automatically streams the whole process in one combined analysis step.

Sonar features a standard role-based authentication system allowing you to secure your instance, create as many users as required, and assign them to groups. A user can belong to more than one group, while access to the various Sonar services and functionality can be fine-grained by assigning appropriate roles.

Two groups have a special status in Sonar:

Of the four roles available in Sonar, one is global, referring to the instance, and the three others are attached to projects:

If a global security system exists within your environment, such as Atlassian Crowd SSO, LDAP, or Microsoft Active Directory, you can delegate all Sonar authentication function to these systems using the appropriate plugins.

The Sonar platform is extensible via a plugin system. More functionality can be added using plugins, either open source or commercial. A dedicated repository located at http://sonar-plugins.codehaus.org/ hosts the Sonar plugin library. From there, you can choose and download the plugins you require for your Sonar instance and read documentation and installation instructions specifically written for each one separately. Plugins enable Sonar to measure more programming languages, add more metrics and rules, and integrate the platform with third-party systems such as LDAP or Continuous Integration build servers.

Some of the more interesting plugins and a brief description of what they do are shown in the following list: