The Java Message Service (JMS) is a Java API that allows applications to communicate with each other using a common set of interfaces. The JMS API provides messaging interfaces but not the implementations.

A JMS provider, such as the webMethods Broker used as a JMS provider, is a messaging system that supports the JMS message interfaces and provides administrative and control features. It supports routing and delivery of messages by means of the JMS API on the client. A goal of JMS is to maximize the portability of JMS applications across different JMS providers.

JMS clients are the programs or components, written in Java, that produce and consume messages.