How to optimise communication layer in an Android app. Learnings from building at Hike Messenger.

1. Building for India.
Gearing for 100 Million users
Paresh Goel
All things Android, Hike Messenger

2. LAUNCH: DEC’2012
AUG’14: 35M USERS IN 20 MONTHS
INDIA: 90% OF USERBASE
2

3. 3
Days
WHERE WE ARE
62.5
50.
37.5
25.
12.5
0.
0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500
Hike Twitter Facebook

4. WHERE WE ARE
4
Days
62.5
50.
37.5
25.
12.5
0.
0 150 300 450 600 750 900 1050 1200 1350 1500
Hike Twitter Facebook

5. BIGGEST INDIAN MOBILE
APP

6. 10 BILLION+ MESSAGES
PER MONTH

7. What does Building for India mean?

8. What does Building for India mean, Technically ?

9. • Network optimisation.
• Catering to low-end devices.

10. Network optimisations
• Most people in India use sachet data packs.
• It costs INR 3 / MB.

11. Client-Server Protocol
• Has to be persistent.
• Takes care of flaky network condition.
• Consumes lesser bandwidth.

12. MQTT (Message Queue
Telemetry Transport)
• Network protocol for broadcasting and
listening for information over network.
• Lightweight: Header to Message ratio is less.
• Publish / Subscribe mechanism.
• Support for QoS Levels.

13. MQTT Message Format
• A MQTT topology has a MQTT server and a
MQTT client.
• The protocol works by exchanging a series of
MQTT Control Packets.

14. MQTT Control Packet
Structure

16. CONNECT
CONACK
SUBSCRIBE
SUBACK
PUBLISH
PUBACK
DISCONNECT
Client Server

17. CONNECT
CONACK
SUBSCRIBE
SUBACK
PUBLISH
PUBACK
DISCONNECT
Client Server

18. CONNECT
CONACK
PUBLISH
PUBACK
DISCONNECT
Client Server
Auto-subscribe

19. QoS Levels
• At most once. QoS=0
• At least once. QoS=1
• Exactly once. QoS=2

20. Active and Passive timeouts.
• GCM Push for passive state.
• Aggressive timeouts for active state.

21. File Transfer
Optimisations.

22. 3 BILLION+ STICKERS
PER MONTH

23. LOCALIZED STICKERS
INDIA

24. Avoid transfer when you can.

25. Don’t load images on scroll.

26. MD5 checksum
MD5
Key
Publish with key
Client Server

27. Use Unique Id
Publish with Sticker Id
Publish with Sticker Id
use local file path
Client 1 Server Client 2

28. Publish with Sticker Id
Publish with Sticker Id
Request File for Sticker Id
File for Sticker Id
Client 1 Server Client 2
Add Entry

29. Transfer based on destination dpi.

30. Chunk sizes to cater to a flaky network connectivity.

31. Multi-threaded download.

32. Still playing: Chunk size could vary on actual speed at runtime.

33. Feature Optimisations
App decisions are also based on minimising
bandwidth consumption.

34. Bulk Packet
In India, users may be offline for long periods of
time.
We send pending messages in one bulk packet.
This reduces headers and corresponding Ack
packets.

35. Last Seen
We moved into a subscription rather than a
broadcast mechanism.

36. Summary
• Network Optimisations should be top priority
• Choose bandwidth-optimised network
protocol.
• File Transfer - MD5, resolution based.
• Feature decisions - optimise for network.

37. ?

38. THANK YOU
GO BIG OR GO HOME
38

39. PARESH GOEL,
HIKE MESSENGER
paresh@hike.in

40. Your code is worth a Million !
hikeathon@hike.in
19-21 Dec