Journey and technologies used in building the Flipkart mobile platforms and apps

1. Building Mobile Platforms for Massive Scale
and Differentiated User Experience
Regunath B, Principal Architect, Flipkart
Amar Nagaram, Sr. Engineering Manager, Flipkart

2. Retail App (there are so many...)
 Search and
navigation
 View product,
reviews
 Buy
 Track status
 Social
integration
 Zoom, Bar-code
scan

3. eBook App (not a common app...)
 Search, browse,
read sample
 Buy, read from
multiple devices
 Gesture interface
 Sync reading
location, offline
mode
 Dictionary, notes

4. slashn Event App(why app..?)
 Location, Schedule,
Speakers
 QR code event pass
 Customize schedule
 Rate presentations

5. Why Build Apps?
• Anytime, anywhere access (mostly)
• Growth in smart phone user base
• Mobile internet(3G, 2G) reach wider than
desktop(DSL)
• Better personalization
• Gesture based user experience
• More secure (2 Factor authentication)
• Simpler checkout
Adoption @ Flipkart : >20% of orders placed and growing

6. Attempt1 : Building Scalable and
Differentiated User Experience

7. Standards and Productivity
Stacks
- Hybrid views (HTML5) for portability
- Standard navigation
- Quick to develop interactions
- Web API
- Wrapper based integration with
backend systems
- Push Notifications(StackMob, AirShip) - Offline experience
- Data availability across devices
- Cloud data service (StackMob,
OpenMobster)

8. Ratings & Reviews(then)

9. Sub-optimal User Experience
• Software on Device : Responsiveness of app,
Resource usage
• Network : Ability to deal with slow/broken
network connectivity
– Latencies of services located in far of geographies
•e.g. 3 seconds to exchange 2K data using StackMob
• API Platform : Latencies, Fault tolerance
• Engagement : Notifications, Usage
– Relevance of Notifications
– Tracking installs, failures in accessing data

10. Attempt2 : Building Scalable and
Differentiated User Experience
Why User Experience Matters
(across platforms, networks, features, time)

11. Cue the Numbers
• Only 16% of users return to an app that fails to
load fast
• Ideal app launch time : 2 seconds
• Average Indian network data speed : 0.9 mbps
• API Platform latencies : has to be < 500ms
 Scale fast
 Install base : 1 M Android installs in 6 months
 Traffic growth : 75% MoM
 Per user engagement growing MoM

12. Architecture decisions
• Native device user interface
• Server controlled layouts – A/B configurable
– Page composition using reusable widgets
• Fault-tolerant, parallel service calls
• Availability vs. Consistency tradeoffs
– Distributed and local caches
• Prevent cascading failures
– Timeouts, Threadpools control resource usage
• Ability to operate in disconnected mode
– Offline data store, sync support

13. Architecture decisions
• User experience on slow networks
– Low resolution images, preference for text over
image
• Content specific user engagement
– Deep linked Push Notifications
– In-app notifications
• Data driven decision making, features
– Usage information, Performance statistics

14. Stacks Optimized for User
Experience
- Native views with optimized rendering
- Gesture navigation
- Fluid, friction free interactions
Jetty, Lego, Phantom FlipCast Notifications FlipSync Offline mode
- Mobile Gateway/API
- Transparent integration into
other backend systems
- Resilience, Low latency
execution
- Multicast (Targeted)
- Personalized
- Platform agnostic
- Interactive
- Context sensitive
-
- Disconnected mode
- Near real-time sync
- Data availability across
devices & web
Hyperion analytics
- Usage information
- Errors/crashes
- Performance statistics
- Soft real-time trends
- Feedback/insights

15. APIs on Lego, Phantom
REST Controllers
PageBuilder PageBuilder PageBuilder
WidgetBuilder WidgetBuilder WidgetBuilder
Handler
Repository
- Jetty Http Interface
- MVC controllers
- Lego libraries
- MVC model builders
- Futures used in
Scatter/Gather data read
patterns
- Phantom Resilience layer
- Availability knobs : timeouts,
fallbacks, throttling
- Real-time monitor
Proxy Command

16. Operating the API Platform –
Phantom Console
https://github.com/Flipkart/phantom (Flipkart OSS)

17. FlipCast Notifications
• Supported Platforms
– iOS, Android, Windows Phone 8
• Features
 Device register/unregister API
 Configurable push message payloads
 Automatic housekeeping for invalid
devices
 Automatic/Transparent retry and
sidelining
 Message history management
 Pluggable data source (Default:
MongoDB)
 Automatic backpressure management
 Unicast, Multicast & Broadcast Push
API
 Auto Batching for multicast & broadcast
push
• Tech stack
– spray.io, akka.io
– RabbitMQ
– MongoDB

18. Hyperion Analytics
• REST style Event API for data injestion
• Replicated and Partitioned Kafka message queue
• Distributed stream processor using Storm
• HBase event data store
• MongoDB Query data store
• Search and aggregation API on query data store

19. Hyperion Analytics

20. Installs, Ratings & Reviews(now)
Installs : 5,000,000 - 10,000,000
Installs : 100,000 - 500,000