When trying to use events for interop between our microservices, engineers often run into the challenge of how to model interactions so as to enable asynchronous communication between their services.

We can look to the past for guidance.

Paper based offices used to be how every business ran. Looking at how they worked can give us a view of how work was done pre-automation, when asynchronous flows of paper were common. Mature business processes were event-driven with in-tray, out-tray and post room driving the flow of work in a business.

In the early 1970s J Paul Morrison  invented Flow-Based Programming, a model in which a system was comprised of a number of applications communicating asynchronously through flows of discrete information packets. 

By looking to these models from the past we can find valuable insights that will show you how you can model a system that uses events to communicate asynchronously today. Along the way we will learn how this can help us understand how modelling techniques like Event Storming echo these older aproaches.

By the end we hope to give you another tool to understand when your system needs to hustle, and when it needs to flow.