To this day, enterprise message queuing is a concept that is not well understood by
most software developers. Commercial message-oriented middleware (MOM) did not
help to encourage adoption of the process; most of the MOMs on the market were
closed source, were costly to buy and support, and required trained system administrators
for proper installation. ActiveMQ was developed to provide an open source alternative:
its central theme is to put the power in the hands of developers. To date, the
ActiveMQ project has been successful in this endeavor by creating a MOM that is easy
to install, administer, and utilize, while providing a large number of unique features.
Today, six or seven years after ActiveMQ was originally created, it’s surprising how
far and widely it is being used. ActiveMQ is a crucial component in many applications.
Used by small businesses and very large enterprises alike, ActiveMQ is deployed
throughout a wide variety of industries around the world including manufacturing,
government, retail, healthcare, finance, military, telecom, and many more. The versatility
of not only ActiveMQ but also event-based systems has appealed to a very large
audience of users and that appeal continues to grow.
In writing a book about ActiveMQ, our intent was to provide a comprehensive
guide for its features and how to use them. Although ActiveMQ implements the JMS
specification, which has not moved in many years, ActiveMQ provides many features
beyond this spec and it has not stopped innovating. As is always the case, authoring a
book about software is a game of chase; as the software evolves, so must the book that
is still being written. We did our best to keep this book up to date with ActiveMQ 5.4.1.
We hope that, by reading this book, you will come to appreciate not only ActiveMQ
but the concepts surrounding event-based systems. After all, some of the largest systems
in the world are designed using events and message queuing.