Xulforge Blog

Mike Connor’s post on Jetpack and Personas has brought up lots of debate surrounding the future of the add-ons ecosystem. Extension developers are concerned about the future of XUL and the extensions they’ve spent so much time and effort on. Others are concerned about the future of the platform and its openness. I’d like to chime in as a veteran extension developer and recent addition to MoCo. This is not an official statement, just my views on the situation.

First of all, let me be very clear about this: there is no short term plan to eliminate the extension platform as we know it. XUL and XPCOM run deep in Firefox. They are Firefox. Eliminating the technologies that make extensions possible would require a rewrite of pretty much everything in the platform, which is massive. I’m not saying this couldn’t happen some time in the future (I don’t know, really), but it isn’t something that can be accomplished within a few weeks, or even a few months. It’s something that requires a great deal of planning and the collaboration of the whole community. Extension developers shouldn’t worry about their add-ons being obsolete overnight.

We should all look into the future, though. Not as something that we’ll have to accept, but as something we can shape. Jetpack and Personas are still experiments in many ways, and there’s much we can do to make them what we want them to be. I personally doubt they will ever reach the point where they will replace the current add-on options, but I am confident that they can come very close, and that’s a big win for everyone.

Jetpack

The goals of the Jetpack project are ambitious: no restarts for install / uninstall, a clean and more stable API, complete security, and a much easier development experience. They’re so ambitious that to think all of these can be accomplished while preserving the flexibility of the current platform would be naive at best.

There are no stable APIs. You can make higher abstractions that are less likely to change. But they will change. Jetpack only makes its add-ons dependent on its API, instead of the XUL/XPCOM platform. So, instead of updating your add-on to the next Firefox version, you’ll update it to the next version of Jetpack, which should happen much less often. That is of course assuming there will be some sort of versioning of the Jetpack API. If that’s not the case, well, then we have bigger problems to be concerned about.

Jetpack, unlike XUL and XPCOM, is not a fully open system. It can’t be. Not without sacrificing the security it’s meant to bring. As a secure system, it should be closed by default, enabling through its API only the features that are considered to be safe and necessary. This limits add-on creativity to the API designers’ imaginations, as opposed to the developers’. On the other hand, in the current system extensions can do pretty much anything. They can read, write and execute files. They can change your preferences and access your saved passwords. They can monitor your online activities and send information to third parties. The only real protection between you and the extensions you install is the review system that all of them have to go through in order to be publicly listed on AMO. A group of reviewers (also known as editors) make sure these extensions are safe to use and respect user choice. Which one is better? To me, the answer is simple: if it’s possible on Jetpack, use Jetpack. It’s simpler and safer. If it isn’t, then fall back to extensions, where you have almost limitless control.

Jetpack add-ons will be easier to develop, and it will be possible to install and remove them without restarts. This is a huge win for users and developers. Many, if not most add-ons will be easily portable to this new platform, and they will benefit from it. It remains to be seen, however, if highly complex (and extremely popular) add-ons like AdBlock Plus, NoScript and Firebug will be able to live in the Jetpack world. These extensions are strongly tied to the platform, and their interactions would be very hard to translate into a general use API. Maybe we can implement jetpack.magic.doWhatNoScriptDoes .

Personas

Personas are not even close to being a replacement for themes. Personas allow some very basic skinning using header and footer images and setting font colors for the main toolbox. Surely they could be extended to include images for the toolbar icons and some more advanced customizations, but that’s not the case now, and even then they wouldn’t be a complete replacement for themes. Themes can change the appearance of the application in very significant ways, and this can’t be accomplished without the complexity inherent in theme development. So, theme developers, you’re not done yet either.

The future

I think the future for extensions and themes is still bright. Jetpack and Personas have shown us how things can be different, and opening the field for new development and competition is a win for all.

There’s much we can do to improve the “classic” add-on world, in the area of documentation and tutorials, and even in the platform itself. We’re being shown how to improve. We should take this as a call to action, and improve. Let’s work on the platforms that will support the development of the future, but let’s not forget the ones that are still active and thriving.

Let’s not forget how we got here.