| Architecting around events has several ramifications. For building up a picture of the world, it's pretty good. It's very nice to be able to replay a log of events and recreate a view of the way things are expected to be; if there's a bug in your code, you can fix it and repeat the replay to get back into a good state (with caveats, sometimes later actions creating events may be dependent on an invalid intermediate state). Whereas mutating updates erase history, perhaps with some ad-hoc logging on the side that is more often than not worthless for machine consumption. For decoupled related action, it's not too bad. If you have some subsystem that needs to twiddle some bits or trigger an action when it sees an event go by, it just needs to plug into the event stream, appropriately filtered. For coordinated action OTOH, e.g. a high-level application business-logic algorithm, you need to start thinking in terms of explicit state machines and, in the worst case, COMEFROM-oriented programming[1]. Depending on how the events are represented, published and subscribed to, navigating control flow involves repeated whole-repo text searching. It's best if your application logic is not very complicated and inherently suitable to loose coupling, IMO. [1] https://en.wikipedia.org/wiki/COMEFROM |