Now it's time to take a closer look at the message itself. In a messaging application, the message is the fundamental unit of communication between two nodes on a network. The message can relay information, suggest or demand a course of action, or request data. In this chapter, you'll find out what constitutes a message in SOAP version 1.2 and how messages are structured, including what kind of content they can contain. You'll then follow the path of a message as it makes its way from a sender to a receiver in an "Indigo" messaging application.