App: Release Gently - Feature Gates & A/B Ashwini Kumar Hotstar @ashwinikumar089 

Background ▸ Rewrite the complete app from scratch. Why? ▸ Old codebase maintenance ▸ Handle the huge scale of 100+ million users. ▸ New features on old screens. e.g. Game on Old Watch Page ▸ Time crunch - IPL was coming!! ▸ Big Bang vs Progressive. Refer our blog: Rearchitecting apps for Scale ▸ Tech stack 

▸ Feature Gate: Ability to turn ON/OFF a feature without requiring an app update ▸ Modular approach. But how to test both screens? Say New vs Old Search ▸ A/B Testing ▸ Users Targeting - Rolling out exclusive features only to certain audiences ▸ Support two Backends at the same time and switch depending upon the performance. ▸ Service which would scale for millions having all the necessary infra already available. 10+ million peak concurrency. ▸ Refer our blog here: App : Release Gently — Feature Gates & A:B Goals 

If the Path Be Beautiful, Let Us Now Ask Where It Leads Anatole France 

Firebase 

HUNT FOR A SAFER PATH ▸ Changes behaviour of app at runtime ▸ Handles the caching by its own. Stores the config in FirebaseRemoteConfig object when activateFetched is called. ▸ Release Gently and Feature Gating ▸ Quirks: Cache Expiration Time!! Firebase Remote Config 

Live Scenarios 

STAGED ROLLOUT New Watch Page ▸ Tons of features: ADs, Game, KeyMoments, Live etc. ▸ Old Watch vs New Watch Page ▸ Firebase Remote Config: Fail-safe approach ▸ Feature-Gate using Users in Random Percentile ▸ More than just a knob. Audiences, Events and A/B ▸ A/B Experiments based on Remote Config ▸ Optimisation Metric ▸ Roll out the leader 

KHEL DEKH. GAME DIKHA. Emoji ▸ Gamification on live streaming ▸ Supporting Android Jellybean & above ▸ Issue with Emoji on the day of IPL launch ▸ Firebase Audience to the rescue ▸ Users in Random Percentile 

ITS ALL ABOUT THE PEOPLE Firebase Audience ▸ Audiences help in creating a segment of users ▸ Segment can be created based on Event or User Properties ▸ We created the segment of users where Emoji was not working as expected ▸ We rolled out the Emoji to all except the affected ones thus preventing unwanted behaviour on Watch Page 

Firebase Audience Creation 

EVENTS & USER PROPERTIES Firebase Analytics ▸ Firebase Events help in getting the insights of user actions ▸ User Properties are attributes which typically describe the segments of the user base. ▸ Firebase logs some properties and events automatically like App Version, Country, Device Brand, Model etc. ▸ Log your own custom property as we did at Hotstar like build_flavor ▸ Log Custom Event to measure your optimisation metric for A/B 

Firebase Remote Config - Creating Condition 

BONUSES Other Perks ▸ Firebase Performance SDK ▸ Provides the insights of how your app is performing. ▸ Logs all the HTTP/S network requests automatically along with app start up time(traces) ▸ Breaks down the perf data based on Device Model, Carrier, OS Level, Country and App Version ▸ Provides the functionality to customise the traces for perf capturing like checking app load time when new screen is created ▸ DebugView to view the logged events 

THANK YOU @ashwinikumar089 @kumarashwini We are Hiring.
 Find more about openings, tech stack and key people here:
 https://tech.hotstar.com/
 @ashwini009