event-handler

Reaction to an Event that produces an externally observable side effect. See Concepts: Event Handler.

Fields

Field	Required	Description
apiVersion	yes	schema.esdm.io/core/v1
kind	yes	event-handler
name	yes	The Event Handler name.
scope	yes	scope.domain reference.
deliveryGuarantee	yes	at-least-once or at-most-once.
idempotency	required when deliveryGuarantee is at-least-once	The idempotency strategy.
handles	yes	Non-empty list of Event references.
sideEffects	yes	Non-empty list of side effects the handler causes.
constraints	no	Named rules under which the handler runs.
description	no	Free-form prose.
metadata	no	Non-semantic labels and annotations.

sideEffects[]

Each entry is one of two shapes:

type	Required fields	Description
external-call	externalSystem, rule	A call to a named External System.
other	rule	Any observable effect that is not a third-party invocation (audit log, metric, cache invalidation).

In both shapes, rule carries the prose description of the behavior.

Example

apiVersion: schema.esdm.io/core/v1
kind: event-handler
name: send-round-started-confirmation
scope:
  domain: golf-club-management
deliveryGuarantee: at-least-once
idempotency:
  strategy: deduplication-key
  key: roundId
handles:
  - boundedContext: round-play
    aggregate: round
    event: round-started
sideEffects:
  - type: external-call
    externalSystem: mailer
    rule: Send the round-started confirmation email to the player.