Product Description
One of the most basic laws of a web application is that the client, not the server, must initiate any communication between the two. There are a number of common–use cases where, ideally, the server would like to talk to the client—dashboards and monitoring apps, chat rooms and other collaborations, and progress reports on long–running processes. Comet (a.k.a. Reverse Ajax) provides a mechanism for enabling this. Comet is moderately complex to implement. But this practical, hands–on book gets you going. In Part 1 of this book, we start by examining the use cases, and look at the simple alternatives to Comet and how far they can satisfy your needs. In some situations, though, only Comet will do. In Part 2, we demonstrate how to set up and run a Comet–based application. With this book, be a part of the next generation, Ajax 2.0. What you’ll learn Find out what Comet is and the trouble with HTTP. See how to achieve push, polling, piggy–backing, raw sockets, and more. Explore some common use cases and a worked example on “magnetic poetry.” Understand what some issues and techniques are including the two–request limit, pub–sub and server architectures, and continuations vs. native Comet. Use implementations of Comet, including Cometd/Bayeaux, Reverse Ajax in DWR, and more. Work through the final example using DWR Framework. Who is this book for? This firstPress title is for Ajax developers who are intrigued by Comet/Reverse Ajax, key to the next generation Ajax 2.0.

CUSTOMER REVIEWS (Average Customer Rating: 4.0 based on 2 reviews)

A little outdated by Trevor Burnham (Ann Arbor, MI)

3 Stars
March 20, 2009
The authors do an excellent job of illustrating the "Comet" process here: Keeping an HTTP request open so that the client can continue to receive content from the server continuously, rather than having to repeatedly query the server for Ajax content. They describe the advantages and potential pitfalls in a good amount of depth without becoming overly detailed for programmers working with a Java framework like Grails. They talk especially about DWR, a fine framework that takes care of the details of Comet and can be easily used in conjunction with other web frameworks. But before you invest in this book, you should be aware of two things: It's very short (like all of the Firstpress books) and only talks about DWR 2.0, while the cutting edge is DWR 3.0. Also, you should think about whether you really need Comet in order to do what you're doing; for most purposes, ordinary Ajax is fine. If you're trying to learn Comet in depth, the DWR documentation is a better resource. And if you're intent on learning Comet quickly, the eBook version of this book might be a better buy.

Easy read and understanding by Mostafa farghaly (Egypt)

5 Stars
December 21, 2008
I've found this book very valuable source written by smart developers, It illustrate Comet aka reverse ajax 2.0 step by step and wrap my mind around all the problems and solutions during comet apps development. Comet is still immature technology but once you read the book you can apply it today in your web apps and achieve collaboration and real-time notification apps using the same technologies you use every day in your job in addition to some HTTP and XHR hacks , although the application ( Magnetic poetry )used to illustrate the technology isnot real world but it succeed in showing how to implement poll, push and biggybacking , long polling and Comet very easy , The rest of the book illustrate using server frameworks like DWR for easy comet , although iam a PHP fan i could apply all DWR concepts easy , then illustrate DoJo comet client-side framework and bayuex protocol , and end up with magnetic poetry appplication using all the techniques in the book , i recommend this book for all front-end engineers :)

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