This document discusses building real-time web applications and introduces SignalR as a library that simplifies creating persistent HTTP connections for real-time functionality. It describes how older techniques like polling and long polling have disadvantages, while newer techniques like web sockets have limited browser support. SignalR abstracts these complexities by automatically negotiating the best transport and allowing real-time functionality to be easily added to applications. It also enables scaling out applications across servers and backing services. Demos and components of SignalR are presented, along with how it provides a fallback mechanism to support older servers and clients.

2. Your Presenter
Shravan Kumar Kasagoni
Software Engineer @ Thomson Reuters
Microsoft MVP – ASP.NET / IIS | MCP
Microsoft User Group Hyderabad
http://theshravan.net
@techieshravan

3. Agenda
Introduction to real-time apps
What is SignalR?
Demos
SignalR Components
Scaleout SignalR

4. Real-time Application?
Real-time functionality is the ability to have
server code push content to connected clients
instantly as it becomes available, rather than
having the server wait for a client to request new
data.

5. Why Real-time?
Users want the latest info,
NOW!

6. Show Me Some Examples
 Twitter, Facebook, Mail - live searches/updates
 Stock streamers
 Auctions
 Interactive games
 Live Scores
 Collaborative apps (google docs, office web
apps)
 Live user analytics (live graphs)

7. How to build real-time web apps?

8. HTTP is an old beast…
Never designed for real-time
communications
 Web is all about request-response
 Web is stateless

10. Periodic polling
 Poll from time to time using Ajax
 Delay in communication due to polling interval
 Wastes bandwidth & latency
Server
Client
Polling interval

11. Long polling
 Poll but doesn’t respond until there's data
 Poll again after data received or after the connection
times out
 Consumes server & threads & connection resources
Server
Client

12. Forever Frame
 Server tells client that response is chucked
 Client keeps connection open until server closes it
 Server pushed data to the client followed by 0
 Consumes server threads
Server
Client

13. HTML5 Web sockets
 Extension to HTTP
 Provides raw sockets over HTTP
 Full-duplex
 Traverses proxies
 It's still a draft
 Not every proxy server supports it
 Not every web server supports it
 Not every browser supports it
 They are raw sockets!

14. too many options

17. What is SignalR?
An open-source series of libraries that provide an
abstraction around persistent HTTP connections
SignalR makes real-time HTTP so easy
it seems like magic that it works
[In English, please]

18. SignalR on Old Servers or Clients

19. SignalR on New Servers and Clients

20. Basically…

21. What does SignalR do?
 Client to Server Persistent connection
over HTTP
 Easily build multi-user, real-time web
applications
 Auto-negotiates transport

23. SignalR Fallback
Long
Polling
Forever
Frame
Server
Sent
Events
Web
Sockets

26. http://shootr.signalr.net
http://firework.cloudapp.net

28. CLIENTS
BACKPLANESHOSTS

30. Three backplanes
 Windows Azure Service Bus
 SQL Server
 Redis

31. Backplane
Load balancing via a common transport mechanism

32. References
http://www.asp.net/signalr/
http://signalr.net/
https://github.com/SignalR/SignalR/wiki

33. Keep in touch
http://theshravan.net
@techieshravan
shravan.kasagoni@outlook.com