WebSockets allow for bi-directional realtime communication between clients and servers over a single TCP connection with low latency. Both the WebSocket API and protocol are standardized, making it a cross-platform solution. Originally for browsers, WebSocket libraries now exist for many languages. WebSockets supersede older techniques like HTTP polling and represent a standard for realtime applications.

1. What are

2. WebShockets
WebSockets represent a long awaited evolution in
client/server web technology.
They allow a long-held single TCP socket
connection to be established between the client
and server which allows for bi-directional, full
duplex, messages to be instantly distributed with
little overhead resulting in a very low latency
connection.

3. Both the WebSocket API and the
WebSocket protocol are
standardised which means the web
now has an agreed standard for
realtime communication between
Internet clients and servers.

4. Originally considered a browser
technology, WebSockets are reaching
far beyond just web browsers and are
becoming a cross platform standard for
realtime communication between client
and server

5. As well as native WebSocket support in
browsers such as Google Chrome,
Firefox, Opera and a prototype Silverlight
to JavaScript bridge implementation for
Internet Explorer, there are now
WebSocket library implementations in
Objective-C, .NET, Ruby, Java, node.js,
ActionScript and many other languages.

6. (from a developer’s perspective)

7. The Internet wasn’t built to be all that
dynamic. It was conceived to be a collection of
HyperText Markup Language (HTML) pages
linking to one another to form a conceptual
web of information.

8. Over time the static resources
increased in number and richer
items, such as images, began to
be part of the web fabric.
Server technologies advanced allowing for
dynamic server pages - pages whose content was
generated based on a query.

9. Soon the requirement to have more dynamic web
pages lead to the availability of Dynamic
HyperText Markup Language (DHTML) all thanks
to JavaScript (let’s pretend VBScript never
existed). Over the following years we saw cross
frame communication in an attempt to avoid page
reloads followed by HTTP Polling within frames.

10. Things started to get interesting with the introduction
of LiveConnect, then the forever frame technique, and
finally, thanks to Microsoft, we ended up with the
XMLHttpRequest object and therefore Asynchronous
JavaScript and XML (AJAX).
In turn, AJAX madeXHR Long-Polling and XHR
Streaming possible. But none of these solutions offered a
truly standardised cross browser solution to realtime bi-
directional communication between a server and a client.

12. Why WebSockets are a game-changer?
Finally,
WebSockets represent a standard for bi-
directional realtime communication
between servers and clients.
Firstly in web browsers, but ultimately
between any server and any client.

13. Why WebSockets are a game-changer?
The standards first approach means that
as developers we can finally create
functionality that works consistently
across multiple platforms.
Connection limitations are no longer a
problem since WebSockets represent a
single TCP socket connection.

14. Why WebSockets are a game-changer?
Cross domain communication has been
considered from day one and is dealt with
within the connection handshake.
This means that services such as Pusher can
easily use them when offering a massively
scalable realtime platform that can be used by
any website, web, desktop or mobile
application.

16. WebSockets vs AJAX
WebSockets don’t make AJAX obsolete
but they do supersede Comet (HTTP
Long-polling/HTTP Streaming) as the
solution of choice for true realtime
functionality.

17. AJAX should still be used for
making short-lived web service
calls, and if we eventually see a
good uptake in CORS supporting
web services, it will get even more
useful.
WebSockets vs AJAX

18. WebSockets should now be the go
to standard for realtime
functionality since they offer low
latency bi-directional
communication over a single
connection.
WebSockets vs AJAX

19. Even if a web browser doesn’t natively
support the WebSocket object there are
polyfill fallback options which all but
guarantee any web browser can actually
establish a WebSocket connection.
WebSockets vs AJAX

20. Created By: Ashish Kumar
Source: http://pusher.com/websockets