Regardless of industry trends like microservices or structured monoliths, asynchronous message-driven systems are on the rise. This can be attributed to the ever growing need to break down complex business processes into a series of small steps connected by a reliable communication mechanism, that can be traced back at least to the landmark Sagas paper by Hector Garcia-Molina and Kenneth Salem.

While these systems inevitably grow and evolve, the key challenge of engineers becomes routing of all the messages that glue the business processes together. In this talk I'll attempt to outline some of the biggest and most common issues and suggest common patterns of dealing with them.

Finally we'll discuss a model for thinking about asynchronous message-driven systems that allows you to make sense of all the routing complexity stemming not only from the business itself but also from all the cruft that you, the architect, have to deal with, such as multiple hosting environments, legacy message brokers, rapidly changing requirements etc.