posted by bsnyder on December 20, 2010 07:45 AM

This article is excerpted from the forthcoming book ActiveMQ In Action (http://bit.ly/2je6cQ) by Bruce Snyder, Rob Davies and Dejan Bosanac (Manning Publications, ISBN: 1933988940)

The first article in this series began by introducing ActiveMQ at a high level. This provided you a picture into where to use ActiveMQ with your applications. The second article dove a bit deeper to demonstrate how to integrate ActiveMQ with Tomcat using local JNDI. This is useful for situations where ActiveMQ should only be accessed by a single application. But what about a situation where more than one application deployed to a single instance of Tomcat needs to access ActiveMQ? This is where Tomcat's global JNDI enters the picture. In this article, I show how to integrate ActiveMQ with Tomcat using a global JNDI configuration.

Integrating ActiveMQ With Tomcat

As mentioned in the previous article, ActiveMQ provides a unique feature that allows a broker to be created via the ActiveMQ JMS connection factory. By creating an ActiveMQ connection factory using a URI for a broker that does not yet exist, the JMS connection will create an embedded instance of the broker. So this means that the creation of the broker is dependent upon the ability to create the ActiveMQ connection. JMS connections are created from a connection factory that is registered with the application server. For this purpose, Java application servers provide a JNDI (Java Naming and Directory Interface) implementation that can be used to expose objects to be used by applications deployed to the container. Objects such as JDBC drivers, JMS resources, transaction managers and so forth can be configured to be accessed using the JNDI API. This is the approach that will be used with the web containers.

Tomcat offers two styles of configuration for JNDI resources, local JNDI context and global JNDI context. Configuring a local JNDI resource means that the resource is only available to a particular web application deployed to Tomcat. Whereas configuring a resource in the global JNDI context means that the resource is available to any web application deployed to Tomcat.

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posted by bsnyder on December 16, 2010 08:03 AM

This article is excerpted from the forthcoming book ActiveMQ In Action (http://bit.ly/2je6cQ) by Bruce Snyder, Rob Davies and Dejan Bosanac (Manning Publications, ISBN: 1933988940)

In the first article in this series, I introduced ActiveMQ at a high level and briefly discussed why and when it might be used. In the next two articles, I will introduce two styles of integrating ActiveMQ with Tomcat. In this article I will discuss the first style of integrating ActiveMQ with Tomcat.

Tomcat supports the ability to configure Java objects as JNDI resources. This is ideal for ActiveMQ because a JMS connection factory is required to access the message broker. ActiveMQ is highly configurable and very flexible. As part of this flexibility, ActiveMQ can be embedded inside an existing JVM via a connection factory or started up as a stand alone server in its own JVM. Both of these styles will be touched upon in this article.

Integrating ActiveMQ With Tomcat

ActiveMQ provides a unique feature that allows a broker to be created via the ActiveMQ JMS connection factory. By creating an ActiveMQ connection factory using a URI for a broker that does not yet exist, the JMS connection will create an embedded instance of the broker. So this means that the creation of the broker is dependent upon the ability to create the ActiveMQ connection. JMS connections are created from a connection factory that is registered with the application server. For this purpose, Java application servers provide a JNDI (Java Naming and Directory Interface) implementation that can be used to expose objects to be used by applications deployed to the container. Objects such as JDBC drivers, JMS resources, transaction managers and so forth can be configured to be accessed using the JNDI API. This is the approach that will be used with the web containers.

Tomcat offers two styles of configuration for JNDI resources, local JNDI context and global JNDI context. Configuring a local JNDI resource means that the resource is only available to a particular web application deployed to Tomcat. Whereas configuring a resource in the global JNDI context means that the resource is available to any web application deployed to Tomcat. The configuration for each type of JNDI style is different, so I will review one style in this article and second style in the next article.

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posted by bsnyder on December 13, 2010 07:04 AM

This article is excerpted from the forthcoming book ActiveMQ In Action (http://bit.ly/2je6cQ) by Bruce Snyder, Rob Davies and Dejan Bosanac (Manning Publications, ISBN: 1933988940)

At one time or another, every software developer has the need to communicate between applications or transfer data from one system to another. Not only are there many solutions to this sort of problem, but depending on your constraints and requirements, deciding how to go about such a task can be a big decision. Business requirements oftentimes place restrictions on items that directly impact such a decision including performance, scalability, reliability and more. There are many applications that we use every day that impose just such requirements including ATMs, airline reservation systems, credit card systems, point-of-sale systems and telecommunications just to name a few. Where would we be without most of these applications in our daily lives today?

When it comes to developing and deploying Java applications, it is extremely common to use Tomcat as a runtime container. As you expand your Java applications, new business needs arise including the ability to communicate with other applications, the need to scale an application architecture and quite possibly the need to decrease application coupling just to name a few. These requirements and many more can be addressed through the use of ActiveMQ with Tomcat.

In a series of articles, you will learn about the integration of ActiveMQ and Tomcat. In the first article, you will learn a bit about Java Servlet technology, Tomcat and you will be introduced to Apache ActiveMQ. Future articles will continue to dive deeper into the topic of integrating ActiveMQ with Tomcat.

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