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Programming Jabber
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 ContentsPART 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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I've set up a Jabber box (an early 1.x release) and played about with it, and it was a *very* good experience. Everything worked as advertised. On the other hand, setting up Jabber with SSL was a confusing process without too much documentation and I eventually gave up. Since SSL is a must for `serious' Jabber use, has there been some progress made on making secure Jabber installations easy to achieve?
I read this book looking to use jabber for automated XML messaging and I'll have to say, it has a lot of nifty features that I'd love to use. Unfortunately, it's never getting deployed in my network. Why?
You can't cluster jabber servers. If the main jabber server goes down, you're hosed. In any application that's worth the effort to deploy, having such a single point of failure is a big problem. Additionally, I was kinda annoyed at how jabber leans so much towards instant messaging. I know, I know, that's what it was built for, but this book is trying to pass it off as an "XML messaging" tool, but it's properties often sway back to IM.
In conclusion, if you wanna fool around with a nifty IM robot that doesn't need to be relied on, jabber is a nifty tool. If you wanna do real XML messaging, try something like xmlblaster.
You could perhaps claim that the task is really to associate an IP address and TCP/UDP port with a person, but you can only realistically use one service per port (port 80 overloading notwithstanding), so you'd have to say that the identification is solely for IM, and so the solution of the problem isn't really useful outside IM applications.
Or you could instead say that the task is to associate an IP address and TCP/UDP port with a person and a service, but now you've got the problem of identifying all services and handling the dynamic nature of port assignment as users become available/unavailable and declare themselves as participating/not participating in the various services. Not impossible, but hard enough that nobody seems to have solved it yet.
What do you mean they cut the power? How can they cut the power, man? They're animals!
Thank you for your response.
:)
The basic applet is just far *too* basic to be of much use to our situation (and I guess many others). For starters, it assumes you want to allow people to create an account on your server - there seems to be no way to shut that off in the client.
The person I spoke with at Jabber.com told me they'd completely rewritten the jabber server to be high-volume capable, but that they wouldn't be releasing that code. Possibly ever, or possibly just much later. It's an investment for them, and they have every reason *to* keep is secret. If it's open, and people could implement it themselves, why would they pay Jabber.com?
I wasn't wanting to edit the user XML files by hand, but create them programmatically for users.
I've see the jdev lists and it looks like most questions get answered, but I'd gone looking and never found an answers on the xml file structure for user files, but many questions about it.
Again, thanks for answering.
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