event

Immutable record of a fact that happened. See Concepts: Event.

Schema

properties:
    scope:
        oneOf:
            - type: object
              properties:
                domain:
                    type: string
                    pattern: "^[a-z][a-z0-9-]*$"
                boundedContext:
                    type: string
                    pattern: "^[a-z][a-z0-9-]*$"
                aggregate:
                    type: string
                    pattern: "^[a-z][a-z0-9-]*$"
              required: [domain, boundedContext, aggregate]
              additionalProperties: false
            - type: object
              properties:
                domain:
                    type: string
                    pattern: "^[a-z][a-z0-9-]*$"
                boundedContext:
                    type: string
                    pattern: "^[a-z][a-z0-9-]*$"
              required: [domain, boundedContext]
              additionalProperties: false
    data:
        type: object
required: [scope, data]

Anatomy

An Event has one of two shapes of scope, expressed as a structural oneOf. The container-owned variant carries domain, boundedContext, and aggregate – this is the common case, an Event that belongs to an Aggregate. The free-standing variant carries domain and boundedContext only, and is reserved for Events that have no Aggregate of their own; these are typically published by DCB-bound Commands. The presence of aggregate is the discriminator.

The data field is a JSON Schema object that describes the immutable payload. As with Commands, the model uses an empty object schema (data: {}) to express "no payload" deliberately, rather than allowing a missing field to imply it.

ESDM does not model Event versioning as a first-class field. An evolved Event is a new Event type with its own name (e.g. invoice-paid, invoice-paid-v2). Migration and upcasting are implementation concerns outside this schema.

description and metadata carry the usual free-form prose and non-semantic attachments. apiVersion is schema.esdm.io/core/v1, kind is event, and name is the Event's kebab-case identifier in the past tense.