Knative: Operator’s Handbook

Complex Delivery with reply

A Service can reply to an event with another event. This reply can further be routed to another Service with another Channel and Subscription:

Complex Delivery with replydiagram

Event replies are defined as part of the Subscription:

apiVersion: messaging.knative.dev/v1alpha1
kind: Subscription
metadata:
  name: subscription2
spec:
  channel:
    apiVersion: messaging.knative.dev/v1alpha1
    kind: InMemoryChannel
    name: channel1
  subscriber:
    ref:
      apiVersion: serving.knative.dev/v1
      kind: Service
      name: service2
  reply:
    ref:
      apiVersion: messaging.knative.dev/v1alpha1
      kind: InMemoryChannel
      name: channel2