Book Image

RabbitMQ Cookbook

Book Image

RabbitMQ Cookbook

Overview of this book

RabbitMQ is an open source message broker software (sometimes called message-oriented middleware) that implements the Advanced Message Queuing Protocol (AMQP). The RabbitMQ server is written in the Erlang programming language and is built on the Open Telecom Platform framework for clustering and failover. Messaging 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. RabbitMQ Cookbook touches on all the aspects of RabbitMQ messaging. You will learn how to use this enabling technology for the solution of highly scalable problems dictated by the dynamic requirements of Web and mobile architectures, based for example on cloud computing platforms. This is a practical guide with several examples that will help you to understand the usefulness and the power of RabbitMQ. This book helps you learn the basic functionalities of RabbitMQ with simple examples which describe the use of RabbitMQ client APIs and how a RabbitMQ server works. You will find examples of RabbitMQ deployed in real-life use-cases, where its functionalities will be exploited combined with other technologies. This book helps you understand the advanced features of RabbitMQ that are useful for even the most demanding programmer. Over the course of the book, you will learn about the usage of basic AMQP functionalities and use RabbitMQ to let decoupled applications exchange messages as per enterprise integration applications. The same building blocks are used to implement the architecture of highly scalable applications like today's social networks, and they are presented in the book with some examples. You will also learn how to extend RabbitMQ functionalities by implementing Erlang plugins. This book combines information with detailed examples coupled with screenshots and diagrams to help you create a messaging application with ease.
Table of Contents (19 chapters)
RabbitMQ Cookbook
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Filtering and forwarding messages


In this recipe we are going to implement a selective message forwarding. We will let the shovel plugin forward the subsets of messages to different destinations. A possible use case of this example is a company with three different sites having the following responsibilities:

  • One that takes book orders

  • One that needs only the orders with london as the routing key

  • One that needs only the orders with rome as the routing key

The aim is to forward messages selectively by adding or removing shovels without touching the source broker as follows:

Getting ready

You need three brokers; we will name them rabbitmq@rabbitmqc1, rabbitmq@rabbitmqShovelLondon, and rabbitmq@rabbitmqShovelRome.

How to do it…

In this example the rabbitmq@rabbitmqc1 broker is the node that the shovels will connect to and the plugin is not necessary, but we need to enable it for the others:

  1. Enable the shovel plugin on the rabbitmq@rabbitmqShovelLondon and rabbitmq@rabbitmqShovelRome nodes as seen in...