Web Push Technology

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Nov 12, 2013 (3 years and 9 months ago)

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1

/ November 2008 / EDS Internal

Web Push Technology

Dušan Chromý

SOA Integration Consulting

Reverse Ajax/Comet Explained


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/ November 2008 / EDS Internal

Web Push Technology

Agenda


Why Comet, first?


How to Comet?


Relation to Ajax


Comet by Example: ODI Showcase




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/ November 2008 / EDS Internal

Web Push Technology

Why Comet?


The web interaction model is characterized by a client
requesting information from the web server


Even Ajax, however novel, follows this model


A web server cannot choose when to send updated
information to a web browser


This makes development of a whole class of applications
difficult for the web, including:


Stock Price Tickers (and event monitoring applications in
general)


Chat & Instant Messaging


Online Multiplayer Games


Online Collaboration


How to notify the web browser timely of server events?


Frequent polling used to be the only option…before Comet


The Challenge


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/ November 2008 / EDS Internal

Web Push Technology

How to Comet?

1.
HTTP Streaming


Never
-
ending stream of JavaScript tags

2.
Long Polling


Slowly answered server request


via XMLHttpRequest or dynamic script tag


“Hang on
-

I’ll see if I have news for you”

3.
HTML5 Server
-
Sent Events


HTTP Streaming standardized, cleaned

4.
HTML5 WebSocket


Brave new upgrade of the HTTP protocol

The Approaches


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/ November 2008 / EDS Internal

Web Push Technology


Comet is to Ajax as


Java is to .NET


Audi is to Mercedes


Coke is to Pepsi


The name “Comet” is a play on “Ajax”


Both Ajax and Comet are umbrella terms for groups
of techniques addressing different needs


Ajax enables interactive web applications


Comet enables web applications to receive events from
the server


The Comet concept is known by several other names


Ajax Push, Reverse Ajax, Two
-
way
-
web, and others

Relation to Ajax


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/ November 2008 / EDS Internal

Web Push Technology

Comet by Example: ODI Showcase


The Showcase lets the user submit a file to ODI
through a web page and shows the progress of the
running ODI process


Server
-
side Technology


ODI sends JMS progress messages


Java Servlet delivers the messages to the client


Oracle ADF Faces web application with JSP display
technology


Client
-
side Technology



Dojo Toolkit to simplify JavaScript development


Let’s see it in action!


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/ November 2008 / EDS Internal

Web Push Technology

Links and References

(1)
Wikipedia: Comet

(2)
http://cometdaily.com

(3)
XML.com: JSON Dynamic Script Tags

(4)
Opera Labs: Server
-
Sent Events

(5)
My Tech Rantings: HTML5 WebSocket





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/ November 2008 / EDS Internal

Web Push Technology

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and values the diversity of its people. © 2007 Electronic Data Systems Corporation. All rights reserved.


Du
šan Chromý


SOA Integration

Consulting

EDS Operations Services GmbH

Eisenstraße 56

65428 Rüsselsheim


Germany

Phone:+49
-
(0)6142 80
5431


mailto:
dusan.chromy
@eds.com