Mozilla has announced plans to offer an annual Extended Support Release (ESR) of Firefox for enterprises and other adopters that don't want to keep up with the browser's new rapid release cycle. Each ESR will receive regular security patches, but will not be updated with new functionality until the next ESR becomes available.

The pace of Firefox releases accelerated considerably last year when Mozilla transitioned to a time-based six-week release cycle. The organization issued six new versions of Firefox in 2011, delivering minor improvements at consistent intervals.

The faster cycle has helped Firefox remain competitive with its rivals in key areas like JavaScript performance because new optimizations can be rolled out as they are ready. The faster cycle has also benefited the Web development community by reducing the amount of time that it takes for Mozilla to roll out support for emerging Web standards.

Although the advantages of the new release model are considerable, it has also posed a number of significant technical challenges. Rapid iteration raised serious deployment challenges for large-scale Firefox adopters and also threatened to destabilize Firefox's large add-on ecosystem.

Complex Web applications that companies use internally tend to support a narrow assortment of browser versions. Corporate IT departments have to do routine testing and certification to ensure that a new browser browser version is compatible with all of the company's relevant systems before they roll it out to users. The rapid release cycle disrupted that process by forcing IT departments to contend with a moving target.

The IT departments couldn't respond by simply choosing not to update to every new version. Due to the faster release cycle, individual versions receive official support from Mozilla for a shorter duration. Companies need to be able to get security updates while avoiding new features and functional changes to the rendering engine.

As we have pointed out in previous reports, the way that corporate Web applications are developed is a large part of the problem. If the developers target Web standards instead of specific browser versions, they can theoretically avoid the kind of compatibility issues that arise from a rapid release cycle. In practice, that will require an industry-wide cultural shift that is unlikely to happen in the near future.

Mozilla had to come up with an alternate update model in order to accommodate the immediate needs of enterprise Firefox users. The ESR concept addresses the testing and certification problem by giving large-scale Firefox adopters a more stable target. They get a version that will remain consistent for a whole year, but will still get back-ported security updates. The model is similar to that of Ubuntu's long-term support releases, which Canonical issues every two years with a five-year support guarantee.

Firefox 10, which is scheduled for release at the end of January, will be the first version with ESR status. A new ESR will be issued every single year, with each individual ESR receiving official support until the next ESR is made available, plus a twelve-week grace period designed for transition time between versions.

Alongside this plan, Mozilla intends to phase out official support for Firefox 3.6 in April. The 3.6 release was issued in 2010 before the transition to the rapid release cycle and aggressive automatic updates. According to statistics from StatCounter, Firefox 3.6 currently represents 4.45 percent of the global browser market. Mozilla will prompt users to upgrade when 3.6 finally gets put out to pasture later this year.

The enterprise has always been a weak area for Mozilla. The organization does not provide official support for rolling out and managing large-scale Firefox deployments. Third parties have filled in some of the gaps by supplying custom MSI installers and specialized tools such as the Client Customization Kit.

The decision to step up and deliver the ESR option, rather than leaving it as an exercise for third parties, is a promising step towards a more enterprise-friendly Firefox. When Mozilla first convened the enterprise working group in 2007, the group set some good goals but didn't accomplishing anything of substance. The new enterprise working group, which drafted the ESR proposal, seems to be in a better position to get things done. It's unclear, however, whether they will be able to go further and address long-standing issues like the need for group policy support and official MSI packages.

The transition to a faster release cycle has largely been beneficial for Firefox and the browser's many users. The current release strategy is more modern and a better fit for the rapidly-evolving world of Web technology. Mozilla has taken some good steps to mitigate the challenges posed by the new model. Offering Extended Support Releases will address one of the most important remaining issues with the rapid release cycle.

Listing image by Photograph by Kevin Buehler