Firefox Hello is this cool WebRTC app we've landed in Firefox to let you video chat with friends. You should try it, it's amazing.
My team was in charge of the server side of this project - which consists of a few APIs that keep track of some session information like the list of the rooms and such things.
The project was not hard to scale since the real work is done in the background by Tokbox - who provide all the firewall traversal infrastructure. If you are curious about the reasons we need all those server-side bits for a peer-2-peer technology, this article is great to get the whole picture: http://www.html5rocks.com/en/tutorials/webrtc/infrastructure/
One thing we wanted to avoid is a huge peak of load on our servers on Firefox release day. While we've done a lot of load testing, there are so many interacting services that it's quite hard to be 100% confident. Potentially going from 0 to millions of users in a single day is... scary ? :)
So right now only 10% of our user base sees the Hello button. You can bypass this by tweaking a few prefs, as explained in many places on the web.
This percent is going to be gradually increased so our whole user base can use Hello.
When you start Firefox, a random number is generated. Then Firefox ask our service for another number. If the generated number is inferior to the number sent by the server, the Hello button is displayed. If is superior, the button is hidden.
Adam Roach proposed to set up an HTTP endpoint on our server to send back the number and after a team meeting I suggested to use a DNS lookup instead.
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