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The importance of processes cannot be overstated. The most basic perspective of a process is that it’s doing stuff and a company must do stuff to make money. Furthermore, process is critical to effectively implementing interoperable systems. So often implementers want to jump right to the message (e.g., purchase order, invoice) without fully understanding individually, within a company, and among a set of trading partners what the process is in which a message sent. Messages are not exchanged in a vacuum. Messages are always exchanged in the context of a process. They’re sent in support of doing stuff.
Frequently a message sequence diagram meets the need for process documentation. Consider the following simple and more involved examples from OAGi.