This document discusses real-time web technologies including server-sent events (SSE), websockets, and polling. It provides an overview of each technology, including how they work, browser support, and server-side support. The document concludes with a demo of websockets in Windows 8 using ASP.NET and WCF and a request for questions and answers.

1. html 5 websockets
Florin Cardașim, twitter.com/@cardasim
Endava
26 nov 2011

2. Agenda
Real-time web SSE, Q&A
WebSockets
Demo: Demo: WebSockets in
long polling Windows 8, ASP.NET
& WCF 4.5

3. How do we implement real-time
web?
periodic ajax polling
comet/long polling/http streaming …
flash/javafx/silverlight
html5 server-sent events
html5 web sockets

4. Polling
Browser connect Server
no
message
connect
no
event
message
connect
event
connect
no
message
connect
no event
message
connect
event

5. Polling
No real-time user experience
Wasted bandwidth, most requests return no
data
Frequent polling determine high server loads

6. Comet/long polling
Browser Server
connect
wait
event
event
connect
wait
event
event
connect
wait

7. Comet/long polling
Real-time user experience
High number of clients determines high
pressure on
bandwidth, memory, threads/processes
DEMO

8. Html5 server-sent events
Browser Server
open event stream
<EventSource>
event event
onmessage
event
event
onmessag
e event
event
onmessag
e

9. Html5 server-sent events
Simulates a server push channel over HTTP
Unidirectional, from server to browser
Standardizes some form of Comet/http
streaming
New html tag: <EventSource>
New mime type: text/event-stream

10. Html5 WebSockets
GET /text HTTP/1.1
Client/Browser Upgrade: WebSocket
Server
Connection: Upgrade
Host: www.websocket.org ...
HTTP/1.1 101 WebSocket Protocol
Handshake
Upgrade: WebSocket ...
TCP comm channel
Full
duplex, bidirectional

11. Html5 WebSockets
Full duplex, bidirectional
Single TCP socket
Standard ports: http/80, https/443
Bandwidth savings
Higher scalability comparing with Comet
In&outside of browser
IETF WebSockets Communication protocol
W3C WebSockets API

12. Server side support
 Socket.IO (node.js)  Socket.IO Fallbacks
 Jetty (Java)  Adobe Flash Socket
 Ruby/EventMachine  AJAX Long Polling
 Python/Twisted  AJAX Multipart
Streaming
 Windows 8, IIS 8, ASP.NET-WCF
4.5  Forever iFrame
 … others  JSONP Polling
http://socket.io/

13. Browser support

14. DEMO: WebSockets
@Microsoft
ASP.NET 4.5
WCF 4.5
Windows 8 Developer Preview
IIS 8
ASP.NET 4.5
WCF 4.5
IE 10, Chrome

15. WebSockets @Microsoft
Your code!
WCF high level
abstractions
ASP.NET high level
WCF WebSocket transport
abstractions
System.Net.WebSockets
ASP.NET HTTP Pipeline
HttpListener IIS (iiswsock.dll)
http.sys

16. References
www.websocket.org
www.paulbatum.com
www.kaazing.me
www.html5labs.com
www.buildwindows.com
www.google.com/search?q=websocket

17. Q&A

18. Please fill your evaluation form
Thank you!
Florin Cardașim, twitter.com/@cardasim
Endava
26 nov 2011

19. WebSockets vs Polling bandwidth
http://websocket.org/quantum.html