Messages serve many purposes: to provide information, to ask a question and request a reply, and to solicit some action on the recipient's part.
Written by Jim Buck, Bryan Meyers, and Dan Riehl
Editor's note: This article is an excerpt from Chapter 16, "Advanced Message Handling," of Control Language Programming for IBM i.
Understanding how messages work is an important part of writing good CL programs. In fact, without at least a basic understanding of messages, your CL programs will be error-prone and, in many cases, unreliable.
IBM i is driven by messages. Messages are used for a multitude of different purposes, including initiating jobs, executing commands, communicating between programs, signaling error conditions, letting users communicate with each other, and letting jobs communicate with users.