2. Web Sockets – Building Real Time App for Web
Sankarsan Bose
26th May , 2012
3. The Real Time “Web”
Real Time Web
- Real time information delivery
- Instant updates, searches
- Facebook, Twitter.. Etc.
Technologies
- HTTP essentially is still stateless
- Technologies/Techniques we have to support the same are
- AJAX (XMLHttpRequest)
- Long Polling
- Comet
Challenges
- Clients polling for data, ideally where server should broadcast
- Overhead of
Multiple TCP connections
Same/similar header data being transferred each time over the wire
Customized ways to tracking or correlating requests and responses.
4. WebSockets - Introduction
WebSockets
- WebSockets is a protocol for two-way communication between client and server
- Uses a single TCP connection.
- Takes away overhead of
- Multiple TCP connections
- Same/similar header data being transferred each time over the wire
- Customized ways to tracking or correlating requests and responses.
- Part of HTML5 initiative
- WebSocket Specs has
- Protocol Specification
- API Specification
- Supported by Google Chrome, Firefox,IE 10
- Server side support by Jetty,Node.js (Socket.io), IIS 8.0 (on Windows 8)
6. WebSocket - API
Client Server
(Browser)
Establish Connection
var ws= new WebSocket("ws://www.websockets.org");
Connection Established
OnOpen event
fired Data Sent to Server
Send method Data Sent from Server
called
OnMessage
event is fired Close Connection
Close method
is called Connection Closed
OnClose
Event is fired
7. WebSockets Protocol
Client Server
(Browser)
Send HTTP Request for protocol switch/upgrade
- If server understands WebSocket protocol
- It issues HTTP 101
- There is a protocol switch
- HTTP connection is no longer used
- WebSocket connection takes over the
underlying TCP connection
