Alvaro Videla - RabbitMQ in Action: Distributed Messaging for Everyone

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To my grandfather, Maximiliano Godoy, who showed me the ways of life. Gracias.

A.V.

To Mama, Papa, and my sister Jaime. Your love, support, and faith in me has made it possible to climb mountains... and to God who always carries me to the other side.

J.W.

Welcome to RabbitMQ in Action. If youre like me, possibly youre thinking, Should I read past page one? Alas, too many technology books are written and published, and not all merit more than superficial attention. So let me invite you to read on, if you think this description fits you:

• You want a practical way to learn about push technology, streaming data, and other messaging patterns.
• You want to achieve professional-level expertise with RabbitMQ, including best practices for design and running in production.

In other words, this book is not just a guide to RabbitMQ. It teaches fundamental design patterns across many use cases. It shows why more applications are using themand what the dos and donts are.

What are these patterns? If youve ever wanted to draw a picture of your system as an information flow or network, rather than as a stack, then youre probably using messaging, or are ready to do so. You may be thinking of data delivery, nonblocking operations, or push notifications. Or you want to use publish/subscribe, asynchronous processing, or work queues. All of these are patterns, and they form part of the design canvas known as messaging.

Messaging is a critical capability: it enables software applications to connect and scale. Applications can connect to each other as components of a larger application, or to user devices and data. Messaging is essentially asynchronous in that it decouples applications by separating the sending and receiving of data. The wonderful thing is that this connection pattern works in the same way at any scale.

Scale is the point. The dominance of the internet as a basis for application delivery has made scale the critical factor in application design. Thinking small is no longer acceptable. Recently the term big data has become fashionable. But everything is big now, compared to only a few years ago.

For example, the number of mobile-connected devices will exceed the number of people on earth soon, probably in 2012. As I write this, Facebook is about to IPO. CTO Bret Taylor said that Facebook would have been a mobile application if the technology had been available when Mark Zuckerberg was building it in his dorm room.

Take a moment to think about that. Most applications used to look like this: you load a document or get data from a database, do some processing, and write the results to disk. Future applications will look more like Facebook: always on, cloud hosted, and accessible anywhere. Input and processing are continuous and automatic, and deliver a filtered stream of information that the user wants, as it happens.

These levels of automation, reach, and scale are impossible without adopting a very specific set of design patterns. It is these patterns that you can learn in this book. Derek Collison, one of the originators of modern messaging technology, memorably described messaging as enabling data in motion. Its hard to imagine an application that doesnt need to move data. So messaging is everywhere.

This book gets you started immediately. The patterns are presented as code examples that you can run, and the authors take special care to help you operate your system as well. With Jason J. W. Williams and Alvaro Videla, you have access to experts whove been running large-scale RabbitMQ systems for years. This book is a natural culmination of their outstanding work sharing these experiences with the community.

After you get a feel for RabbitMQ, its very easy to get help and find more examples via the extensive RabbitMQ user community, regardless of which languages youre writing code in. This makes RabbitMQ an excellent choice for your messaging needs.

I hope this has whetted your appetite to turn the page and read on. There will be messages, and there will be rabbits, and all will be revealed.

ALEXIS RICHARDSON

COFOUNDER AND FORMER CEO

RABBIT TECHNOLOGIES, LTD.

SENIOR DIRECTOR

VMWARE CLOUD APPLICATION PLATFORM

Writing this book has been like discovering RabbitMQ itselfencountering a problem that needed solving, but not knowing what the solution looked like. Until May 2010, we didnt even know each other. We both had been active in the RabbitMQ community for the past two years, but wed never actually bumped into each other. Then one day a conversation with Alexis Richardson (Rabbits CEO at the time) introduced Alvaro and me to each other, and made what you hold in your hands possible. What we had in common was a desire to write down in a single place all the knowledge we had acquired about RabbitMQ the hard way. Back in 2010, that knowledge was (and today still largely is) scattered across the internet in a smattering of blog articles and terse technical tutorials. In other words, we both wanted to write the book we wished had existed when we started with RabbitMQ two years earlier.

Neither of us came from a traditional messaging background, which made us fast friends and has largely informed the tone of