No matter how good a tool is, it normally won't provide all the user needs out of the box. As such, it is important to provide a means by which the tool can be extended to provide additional functionality. Such extensions can turn an already good tool into a great one.

JMeter is no different. It provides extension points in the form of plugins. Since JMeter is written in Java, plugins are nothing more than compiled byte code packaged as Java Archives (JARs).

In this chapter, we will detail how to extend JMeter's functionality by installing some excellent and well-thought-out plugins, and dive into the details of how to use some of the components they provide. In the last recipe, we teach you how to write a custom JMeter plugin from scratch.