Developing Real-Time and Asynchronous Web Applications

Jess ChadwickArchitect / RIA Specialist

weblogs.asp.net/jesschadwickjesschadwick@gmail.com

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The Real-Time Web

• Information as it happens

• Always Connected

Why Should I Care?

•User Interaction, aka “Social Networking”

•News

Ok, you’ve sold me.

Let’s do it!

The Web Isn’t Real-Time!

Real-Time Web

1,000’s of users connected at once

The Traditional Web

One user at a time

Real-Time Web Hacks

Real-Time Web Hack #1:

Polling

PollingBenefits Drawbacks

• Takes advantage of how the web really works

• Reliable

• Universal browser support

• Wasteful – requests occur regardless of data

• Drains server and network resources

• Doesn’t scale

Real-Time Web Hack #2:

Long Polling

Long PollingBenefits Drawbacks

• Uses “standard web techniques”

• Less wasteful – fewer requests than “regular” polling

• Universal browser support

• Less reliable – frequent broken connections

• Based on request-response interaction (might be some delay between requests)

Real-Time Web Hack #3:

Server-Sent Events

Server-Sent EventsBenefits Drawbacks

• True real-time

• Rich JavaScript API

• Universal browser support…

except

• Less reliable (broken connections)

• One-way communication (client server)

Real-Time Web Hack #4:

Web Sockets

WebSocketsBenefits Drawbacks

• True real-time

• True bi-directional communication

• Rich JavaScript API

• Good browser support…

except and Opera

• Emerging standard

• Doesn’t use “standard web techniques”

• Less reliable (broken connections)