Message-driven

Reactive systems use asynchronous messaging to flow information through the different components with very loosely coupling, that allows us to interconnect those systems in isolation. We could think of this as if we are connecting streams through pipes, one service could subscribe to another to get some information and the second service could be subscribed to a couple of additional services to combine the data and return it back to the original service.

Each of those services does not know why or how that information is used, so they have little information about the dependencies. This allows us to replace those pieces easily, but as well as handling errors in case of failure, we could simply just create a stream of errors with other receivers that will handle and process them.

But the manifesto speaks about applying back pressure; we need to understand that concept further.