This document summarizes a presentation about building real-time web applications using Socket.IO, Node.js, and Redis. It introduces Socket.IO for enabling real-time bidirectional communication across browsers. It then discusses using Redis for data persistence and as a pub/sub messaging system to integrate components and ensure scalability. The document provides code examples and addresses questions about authentication, load balancing, and configurations.

1. Real-time Web Application with
Socket.IO, Node.js, and Redis
York Tsai, JSDC 2013

2. Who is York
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http://www.linkedin.com/pub/york-tsai/13/bb/8a8
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https://twitter.com/yorktsai
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https://www.facebook.com/yorktsai
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VP Engineering @ EZTABLE

3. Never Live Demo!
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http://jsdc.york.tw/
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I hope this work on my (and yours) computer ...

5. You may Have Heard About
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Forever Iframe
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XMLHttpRequest Long Polling
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Cometd
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Websocket
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http://en.wikipedia.org/wiki/Comet_(programming
)
TL;DR

6. Socket.IO
●
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Cross browser (including IE 6)
Real-time and bi-directional persistent
connection (WebSocket)
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Very simple to use
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Javascript!

7. Start a Server

8. Sending and
Receiving Events

10. Select Receivers for
Events

11. Broadcasting

12. Rooms

13. Single Target

14. Multiple Applications?

15. Namespacing

16. How About New
Connections?

17. Data Persistence
●
●
Need a persistence layer
Get data from the persistence layer whenever a
new connection established

18. Integration
I have component X,Y,Z want to send/receive data
from user's browser

19. Pub/Sub or Message
Queue
Messaging system usually supports both

20. Pub/Sub
Digram from Python's Website

21. Redis
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Super-fast in-memory data structure server
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Pub/Sub
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Rich client libraries
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Zero install and easy to operate

22. 3 Commands
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SUBSCRIBE channel
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UNSUBSCRIBE channel
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PUBLISH channel message

23. In addition...
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Connect multiple node.js server to one redis
channel
Scalability!

24. Two Connections per Server

25. Redis-backed Pub/Sub
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Two clients required: one for pub, one for sub
Use one channel, add metadata to your
message

26. Redis-backed Pub/Sub

27. Frequently Asked
Questions

28. SSL?
Yes!

29. SSL Server

30. SSL Client

31. Cross domain?
Yes! (If use WebSocket or
JSONP)

32. Authentication?

33. Authentication
●
●
Cookie & Session
Cookie does not cross domain, use SSL +
Access Token instead

34. Load Balancing?
Yes! (If use Nginx >= 1.3.13)

35. Sample Nginx Configuration

36. Load Balancing using ELB
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ELB (Elastic Load Balancer)'s HTTP(S) proxy
does not understand websocket requests
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Use TCP/SSL, instead of HTTP/HTTPS
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No session stickyness
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No X-Forwarded-For header

37. Scalability
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Single thread
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2500~3500 connections per process
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As many processes as you want

38. Configurations
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store (default: MemoryStore, single process
only)
transports (default: websocket, htmlfile, xhrpolling, jsonp-polling)
authorization (default: false)

39. Configurations - transports

40. Thank You!
The slide is also the live demo itself. Please check
the following repo!
https://github.com/yorktsai/jsdc2013