This Week in Glean: Glean on Desktop (Project FOG)

(“This Week in Glean” is a series of blog posts that the Glean Team at Mozilla is using to try to communicate better about our work. They could be release notes, documentation, hopes, dreams, or whatever: so long as it is inspired by Glean.)

The Glean SDK is doing well on mobile. It’s shipping in Firefox Preview and Firefox for Fire TV on Android, and our iOS port for Lockwise is shaping up wonderfully well. Data is flowing in, letting us know how the products are being used.

It’s time to set our sights on Desktop.

It’s going to be tricky, but to realize one of the core benefits of the Glean SDK (the one about not having to maintain more than one data collection client library across Mozilla’s products) we have to do this. Also, we’re seeing more than a little interest from our coworkers to get going with it already : )

One of the reasons it’s going to be tricky is that Desktop isn’t like Mobile. As an example, the Glean SDK “baseline” ping is sent whenever the product is sent to the background. This is predicated on the idea that the user isn’t using the application when it’s in the background. But on Desktop, there’s no similar application lifecycle paradigm we can use in that way. We could try sending a ping whenever focus leaves the browser (onblur), but that can happen very often and doesn’t have the same connotation of “user isn’t using it”. And what if the focus leaves one browser window to attach to another browser window? We need to have conversations with Data Science and Firefox Peers to figure out what lifecycle events most closely respect our desire to measure engagement.

And that’s just one reason. One reason that needs investigation, exploration, discussion, design, proposal, approval, implementation, validation, and documentation.

And this reason’s one that we actually know something about. Who knows what swarm of unknown quirks and possible failures lies in wait?

That’s why step one in this adventure is a prototype. We’ll integrate the Glean SDK into Firefox Desktop and turn some things on. We’ll try some things out. We’ll make mistakes, and write it all down.

And then we’ll tear it out and, using what we’ve learned, do it over again. For real.

This prototype won’t have an answer for the behaviour of the “baseline” ping… so it won’t have a “baseline” ping. It won’t know the most efficient way to build a JavaScript metrics API (webidl? JSM? JSContext?), so it won’t have one. It won’t know how best to collect data from the many different processes of many different types that Firefox now boasts, so it will live in just one.

This investigative work will be done by the end of the year with the ultimate purpose of answering all the questions we need in order to proceed next year with the full implementation.

That’s right. You heard it here first:

2020 will be the year of Glean on the Desktop.

:chutten