This document discusses building real-time web applications using ExpressJS and SocketIO. SocketIO allows for bidirectional communication between client and server through websockets. It handles establishing the websocket connection and provides events for sending and receiving data. This enables the server to push updates to clients in real-time without the client repeatedly requesting information. An example given is building a plane status board that updates automatically every time a flight's status changes, rather than requiring the client to check status every second. Key features covered include sending/receiving events, storing client data, namespaces, acknowledgements, broadcasting, and supporting mobile devices.

1. Realtime Web Applications wit ExpressJS
Hüseyin BABAL
Software Developer, CSM
@Sony Eurasia

2. A Scenario...

3. Plane status board…
Updating board on every flight
Check flight status for every
second?
Let’s code that board software...

5. Good Code, but this is
something like...

7. Yeah, client side
server bombing...

8. It would be better if
server side inform
client on any update...

10. What is SocketIO?

11. ●
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Care-Free realtime 100% Javascript
Cross-Browser and mobile device
Wrapper for the Websocket
Learnboost

12. Go back to origin...

13. Websocket?
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Full-duplex comm. channels over TCP
Only its handshake interpreted by HTTP servers
Push server data to client browser
80 port and no firewall prevent

14. Handshake

16. Clients sends base64 encoded string
Server appends a magic string to it and encrypt
SHA-1 after then base64
Example...

17. Client: x3JJHMbDL1EzLkh9GBhXDw==
Server:
x3JJHMbDL1EzLkh9GBhXDw==258EAFA5E914-47DA-95CA-C5AB0DC85B11 then SHA1.
base64(above appended string) =
HSmrc0sMlYUkAGmm5OPpG2HaGWk=

18. In SocketIO, you don’t
need to know all this
stuffs

19. Send / Receive Events

20. Store client data

21. Namespace

22. Volatile Messaging

23. Acknowledgement

24. Broadcasting

25. Quickies
ExpressJS
https://github.com/visionmedia/express
SocketIO
https://github.com/LearnBoost/socket.io
Learnboost
https://github.com/LearnBoost
Websockets
http://en.wikipedia.org/wiki/WebSocket
Button Click Game
http://btnclick.herokuapp.com/signin
Heroku Websockets
https://blog.heroku.com/archives/2013/10/8/websockets-public-beta

26. Mobile?
Will Be Demonstrated
on Next BBS

28. Thanks