Sometime it is needed to use custom JAVA code to processes current message. Developed custom code is known as Java Component. How mule knows which method should invoke and what parameters should be there passed? There are some rules that your class may full fill in order to work without any additional configuration. However when you have more sophisticated use case or class is fairly complex you would probably need Entry Point Resolver configured. I will explain on simple examples some of them. This is valid for Mule version 3.x. In next article I will describe in more detail new Java Module available in version 4.x.