Mozilla Add-ons Blog

Justin Scott has worked hard on creating a compatibility dashboard to help us understand how the add-ons universe is preparing for new versions of Firefox.

The live version is up on addons.mozilla.org. Check it out!

Cross-posted from Justin Scott’s blog.

I recently posted about the start of the campaign to get add-ons ready for the upcoming release of Firefox 3.1, and wanted to explain what our goals are and how we’ll be tracking progress.

As with previous Firefox releases, we’re aiming to have 90% of add-ons that make up the top 95% of add-on usage compatible with Firefox 3.1. That’s not an easy goal to comprehend, so I’ll explain what it means and why we do it.

Every day, the Mozilla Add-ons website gets around 135 million update checks from add-ons installed in Firefox and Thunderbird applications all over the world to determine if any updates are available. While there are some extensions that account for several million of those pings alone, there are many extensions that are not as popular and may have less than 100 active daily users. To make sure our outreach efforts benefit the most end users, we rank the add-ons by their number of active daily users and focus on helping the add-ons that make up 95% of the total add-on usage.

As shown in the above graph, only 861 add-ons as of last Wednesday make up 95% of the total update pings, while 5% is accounted for by the much larger number of 4943 add-ons. Our goal is to get 90% of these 861 add-ons compatible with Firefox 3.1.

For the Firefox 3 effort (Operation Threedom), Alex Polvi created a status bar page that helped visualize our current progress. For 3.1, we’re taking it a step further and integrating a Compatibility Center within AMO that can always be checked for the latest progress.

The new tool isn’t available yet, but should be within a week or so. Here’s a screenshot of our current progress:

As shown, we currently have 20% compatibility. The report is customizable by version, so the current Firefox 3 version of the chart shows 94% compatibility. More screenshots and progress can be found in bug 460309.

We’ll be posting periodic updates on the progress of the Firefox 3.1 compatibility push to the new Add-ons Blog and in various other add-on communication channels.

We’ve seen reports from the field and blogosphere that Firefox 3.0.1 has somehow broken compatibility for many add-ons. This is indeed not the case. When add-on authors publish their add-on they declare the compatibility range for an add-on. It typically looks like “2.0 to 3.0.*” – meaning that at minimum, this add-on requires Firefox 2.0 and works with any maintaince release of Firefox 3.0. (End of the compatibility range is also called the maxVersion).

Some add-on authors have erroneously used “3.0″ as their maxVersion so when users with these add-ons upgrade from Firefox 3.0 to Firefox 3.0.1, the add-on gets disabled. We encourage these add-on authors to use “3.0.*” as their maxVersion.

We have verified that the majority of add-ons hosted on AMO with Firefox 3 support have “3.0.*” in their compatibility range but there are many sites from where add-ons can be acquired.

Now that Firefox 3.0 Release Candidates are starting to become available, we have made modifications to AMO to accept the production version numbers for Firefox 3. In particular, we have added “3.0″ and “3.0.*” as valid Firefox compatible versions. The full application compatibility list is available here.

What this means for you as an add-on author is that after you test with the Firefox 3 release candidates, you can use the Developer Tools section on AMO to bump your version number without having to upload a new version of your add-on.

For completeness, if you want to support Firefox (and none of the alpha’s, betas and pre-releases), here are the recommended version ranges (minVersion – maxVersion) to use:

• Firefox 2: 2.0 – 2.0.0.*
• Firefox 3: 3.0 – 3.0.* (Note: that with Firefox 3, it’s a three part version number)