wow-api/me.ahoo.wow.api.event/DomainEvent

DomainEvent

interface DomainEvent<T : Any> : EventMessage<DomainEvent<T>, T> , Named, Revision

Represents a domain event published by an aggregate in response to a command.

Domain events capture significant business occurrences that have happened within an aggregate. They are immutable facts about past actions and serve as the primary mechanism for communicating state changes to other parts of the system.

Domain events follow declarative design principles (idempotent, similar to Kubernetes apply or Docker image layers). During event sourcing, aggregates should simply apply domain events as overlay layers without complex logic or conditional checks, eliminating the need for explicit sourcing functions.

Key characteristics:

Immutable: Events represent facts that cannot be changed
Named: Each event has a specific business meaning
Versioned: Events carry version information for compatibility
Sequenced: Events maintain order within an aggregate's lifecycle

Author

ahoo wang

Parameters

The type of the event body payload

Properties

aggregateId

abstract override val aggregateId: AggregateId

The unique identifier of the aggregate that published this domain event.

aggregateName

abstract val aggregateName: String

The name of the aggregate.

body

abstract val body: T

The typed payload of the message.

commandId

abstract val commandId: String

A unique identifier for this command instance.

contextName

abstract val contextName: String

The name of the bounded context this entity belongs to.

createTime

abstract override val createTime: Long

The timestamp when this message was created, as a Unix timestamp in milliseconds.

header

abstract val header: Header

The header containing metadata about this message.

abstract val id: String

Represents a unique identifier for the implementing entity.

initialized

open val initialized: Boolean

A computed property that indicates whether the entity has been initialized. Returns true if the version is greater than UNINITIALIZED_VERSION. This property is ignored during JSON serialization.

isInitialVersion

open val isInitialVersion: Boolean

A computed property that indicates whether the entity is at its initial version. Returns true if the version equals INITIAL_VERSION. This property is ignored during JSON serialization.

isLast

open val isLast: Boolean

Indicates whether this is the last event in the current event stream.

isReadOnly

open val isReadOnly: Boolean

Indicates whether this message is in read-only mode.

name

abstract val name: String

The name of the entity.

ownerId

abstract val ownerId: String

The unique identifier of the resource owner.

revision

open override val revision: String

The revision/version of the aggregate when this event was published.

sequence

open val sequence: Int

The sequence number of this event within the aggregate's event stream.

version

abstract val version: Int

The current version number of the entity as an integer. Versions are monotonically increasing and start from 1 for initialized entities. A version of 0 indicates an uninitialized state.