Programming Jabber

Reader cpfeifer contributes the review below of O'Reilly's Programming Jabber: if your job (or hobby) includes instant messaging in all its glory, Jabber is a free-beer, free-speech framework for setting up instant messaging systems not bound to a single server in the middle. As cpfeifer points out, instant messaging can mean a lot more than popping an on-screen note to your friend in Des Moines -- machines and programs can use a general purpose communication system like this, with no human middleman required. Programming Jabber author D.J. Adams pages 4555 publisher O'Reilly rating 9 reviewer http://cpfeifer.blogspot.com ISBN 0596002025 summary A detailed guide for developers to understanding and extending the Jabber messaging framework. Examples in Perl, Python and Java. The Scenario

Jabber was first conceived by Jeremie Miller (pic) in early 1998 in an effort to unify the disparate instant messaging networks. Instant Messaging networks rely on the network effect to gain and retain marketshare. The concept is the same when applied to any sort of participatory network whether it's a junk exchange, or content exchange, the value of the network increases with the square of the number of participants.

If this is true, then doesn't it follow that it is in the best interests of the IM networks to establish peering agreements with each other so that their users can directly contact users on other networks without having to install each client?

Hello, Jabber.

When I first picked up this book, I expected to understand the Jabber protocol in sufficient depth to implement my own IM client. Instead, the approach this book takes is that Jabber isn't just an XML-based protocol strictly for IM, rather it is a general purpose event notification protocol that has some very nice message routing and user management features built into it. While i was reading about the messages that Jabber has defined as part of the protocol, I could easily see other applications/devices generating Jabber messages to notify subscribers (either other systems, or people) of events.

Part 1 of the book focuses on getting you up to speed on the basics of Jabber technology: motivation, major features, XML protocol sample and compiling/configuring your own Jabber server. Chapter 2 presents the "10,000 foot view" of Jabber technology. In here you will find a sample client-query request/response flow with full HTTP headers, discussed step by step. The next two chapters are a very in-depth discussion of installing and configuring your own Jabber server. When you dive into a custom configuration of a fleet of Jabber servers (a "constellation" in Jabber terminology), it really starts to hit home that the real problem Jabber solves is far deeper than just IM.

From there, part 2 kicks off with a detailed discussion of the most basic building blocks of Jabber technology: resource identifiers, XML handling mechanism and the set of XML elements/attributes that make up the vocabulary of the Jabber protocol. Each element/attribute is presented with an annotated example and sample client/server interactions where appropriate. Examples can make or break a technical book, and these examples do a good job of illustrating how the element/attribute is used.

The following chapters take you through using standard Jabber features, user registration/authorization, messages, presence, groupchat, components and the event model to enable new applications. One very interesting application presented is enabling developers to receive CVS commit notifications via Jabber.

What's Bad?

I know the /. community is suspicious of glowing book reviews where everything is wonderful and nothing could be done to improve the book, so I'll nitpick. My major problem with this book is that the overwhelming majority of the sample applications are written in PERL/TK. This isn't a problem in and of itself, but I'm not a PERL/TK developer. If I build a Jabber solution, it will be in java, so PERL/TK samples don't do me a lot of good. I think equal time should be given to implementing Jabber using the two most-used languages, as defined by the number and activity of open source projects using Jabber technology.

What's Good?

This book covers everything relevant to Jabber technology, from lowest level inner workings and extensibility examples for developers to configuration and deployment for admins. Most of the book is spent looking directly at the Jabber XML protocol, instead of a specific API implementation. This way, the book covers the technology and doesn't get lost in how one particular API models the protocol.

So What's In It For Me?

If you want to implement an inside-the-firewall IM solution for your company/group/tribe or investigate integrating event notification into an application, this is a great starting point. If you're just curious about Jabber and want to know how it works, then this will give you enough information to get you hooked.

Table of Contents

PART 1: Getting Started with Jabber

• Chapter 1. Introducing Jabber
• Chapter 2. Inside Jabber
• Chapter 3. Installing the Jabber Server
• Chapter 4. Server Architecture and Configuration

PART 2: Putting Jabber's Concepts to Work

• Chapter 5. Jabber Technology Basics
• Chapter 6. Jabber Namespaces
• Chapter 7. User Registration and Authorization
• Chapter 8. Using Messages and Presence
• Chapter 9. Groupchat, Components, and Event Models
• Chapter 10. Pointers for Further Development

Appendix A. The Jabber.xml Contents

Appendix B. The IQRPC Classes for JabberRPCResponder

Index

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Comments

Jabber : great concept, awful reality.

[mosch]

Jabber seems like such a good idea at first, you may find somebody in your corporation saying 'hey, let's run a jabber server internally instead of using desk phones, cell phones, email or our shoes.' Let me be very clear about this, if somebody says this, even if they make it sound good, they should be fired on the spot.

Problem Number One: The server sucks. Once you start using jabber, you get the joy of watching your client disconnect for no apparent reason, quite regularly.

Problem Number Two: The gateways suck. Jabber has a cool concept where it can provide a gateway to other instant messengers, such as AIM. They crash. A lot. Additionally, you'll find that the jabber gateways can't block senders, so remember that psychopath who is suing the company and you don't want to even know if he's trying to contact you? Too fucking bad, suddenly his messages pop right up.

Problem Number Three: The client sucks. First of all, it crashes (have you noticed a pattern here, yet?), and secondly it has a terrible concept of what should happen to window focus when an incoming message arrives.

Problem Number Four: It's not neccessary. Everybody already has a desk phone, a cell phone and email. Many people also have pagers, wireless email and such. The problem isn't a lack of methods with which to communicate. Adding jabber will not make your company more competitive, reduce costs, improve communication or improve morale.

The moral of the story? Shoot anybody who uses jabber, and you'll save yourself a lot of trouble in the long run.