If an application wants to invoke the functionality provided by another application, the most commonly used method is remote procedure invocation. But if remote procedure invocation has to be used along with the concept of messaging, command message patterns are very useful. The diagram of the command message pattern is depicted as follows:
A command message is a message that is reliably used to invoke a procedure that is running in another application. There is no specific type for a command message. Command messages are normal messages that have a command embedded in them.
