event_handler for multiple services about nameko HOT 4 CLOSED

Hi (and thanks)

in nameko, each service "owns" its own events, so in that sense it doesn't quite make sense to talk about "the same" event from different services. However, if the apis (event data) are compatible, you can stack the entrypoint (any method can be exposed as multiple entyrpoints), e.g.

@event_handler("service_a", "event")
@event_handler("service_b", "event")
def bla(self, payload):
    pass

would that do?

from nameko.

hi,

yes that's also a solution. I will use my own EventHandler to avoid code duplications.

thx,
chris

from nameko.

sure. one of our design goals is to keep things composable enough that you can replace parts to suit your exact use-case

note that the decorator implementation you are overriding is designed to work for any entrypoint. since you have a concrete use-case, you can simplify it (e.g. cutting out the second half since an event-handler decorator always takes arguments)

from nameko.

@chassing feel free to tell me to mind my own business but I would recommend against having a custom subclass like this, for a number of reasons:

• Entrypoints were designed to stack for exactly this use-case.
• By overloading Entrypoint.decorator you've made your application brittle to changes in this "internal" nameko code.
• (Subjective but) I don't consider multiple @event_handler decorators to be duplications. Each one is an explicit declaration, and having them separate will make for easier refactoring in the future. If you're listening to the same event from more than a couple of services you should consider whether your service architecture is correct.
• Adding ~25 lines of complex decorator code is a lot less maintainable than "duplicating" these simple event handler declarations.

Just my 2¢. Can you write about what your specific use-case is?

from nameko.