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

EventMessage

interface EventMessage<SOURCE : EventMessage<SOURCE, T>, out T> : NamedBoundedContextMessage<SOURCE, T> , CommandId, NamedAggregate, Version, AggregateIdCapable, OwnerId, SpaceIdCapable

Represents a domain event message within the Wow framework's event sourcing architecture.

This interface serves as the base marker for all domain events, providing a comprehensive set of identifiers and metadata necessary for event processing, correlation, and tracking in distributed systems. It combines multiple capability interfaces to provide a complete event representation.

The EventMessage is the fundamental unit of state change in the event sourcing paradigm. Each event represents a fact that has happened in the domain, and together they form an immutable sequence of state changes for aggregates.

Inherited Capabilities

The interface extends multiple capability interfaces, each serving a specific purpose:

NamedBoundedContextMessage: Identifies the bounded context that produced this event
CommandId: Correlates the event with the command that triggered it
NamedAggregate: Identifies the aggregate type that this event belongs to
Version: Tracks the aggregate's version after applying this event
AggregateIdCapable: Identifies the specific aggregate instance
OwnerId: Tracks the owner who created/modified this event
SpaceIdCapable: Supports namespace-based data layering within tenant context

Usage Example

data class OrderCreatedEvent(
    override val aggregateId: String,
    override val aggregateVersion: Int,
    override val commandId: String,
    override val tenantId: String,
    override val ownerId: String,
    override val spaceId: String,
    val orderId: String,
    val customerId: String,
    val totalAmount: BigDecimal
) : EventMessage<OrderCreatedEvent, OrderCreated>

interface OrderCreated

Since

1.0.0

Parameters

SOURCE

The concrete type of this event message, used for self-referential typing

The event type marker, typically an empty interface for type-safe event handling

Inheritors

DomainEvent

Properties

aggregateId

abstract val aggregateId: AggregateId

The aggregate ID used to uniquely identify an aggregate instance.

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 override 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.

isReadOnly

open val isReadOnly: Boolean

Indicates whether this message is in read-only mode.

ownerId

abstract val ownerId: String

The unique identifier of the resource owner.

spaceId

abstract val spaceId: SpaceId

The namespace string used for data layering under a tenant. This value should be non-null and represent a valid identifier for the data layer. An empty string indicates the default namespace for the tenant.

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.