Package kalix.javasdk.eventsourcedentity

Class EventSourcedEntity<S>

Object

kalix.javasdk.eventsourcedentity.EventSourcedEntity<S>

Type Parameters:

S - The type of the state for this entity.

public abstract class EventSourcedEntity<S>
extends Object

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	EventSourcedEntity.Effect<T>	A return type to allow returning forwards or failures, and attaching effects to messages.

Constructor Summary

Constructors

Constructor	Description
EventSourcedEntity()

Method Summary

Modifier and Type	Method	Description
void	_internalSetCommandContext(Optional<CommandContext> context)	INTERNAL API
void	_internalSetCurrentState(S state)	INTERNAL API
void	_internalSetEventContext(Optional<EventContext> context)	INTERNAL API
protected final CommandContext	commandContext()	Additional context and metadata for a command handler.
protected final S	currentState()	Returns the state as currently stored by Kalix.
protected final EventSourcedEntity.Effect.Builder<S>	effects()
S	emptyState()	Implement by returning the initial empty state object.
protected final EventContext	eventContext()	Additional context and metadata for an event handler.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

EventSourcedEntity

public EventSourcedEntity()

Method Details

emptyState

public S emptyState()

Implement by returning the initial empty state object. This object will be passed into the command and event handlers, until a new state replaces it.

Also known as "zero state" or "neutral state".

The default implementation of this method returns null. It can be overridden to return a more sensible initial state.

commandContext

protected final CommandContext commandContext()

Additional context and metadata for a command handler.

It will throw an exception if accessed from constructor or event handler.

_internalSetCommandContext

public void _internalSetCommandContext(Optional<CommandContext> context)

INTERNAL API

eventContext

protected final EventContext eventContext()

Additional context and metadata for an event handler.

It will throw an exception if accessed from constructor or command handler.

_internalSetEventContext

public void _internalSetEventContext(Optional<EventContext> context)

INTERNAL API

_internalSetCurrentState

public void _internalSetCurrentState(S state)

INTERNAL API

currentState

@ApiMayChange
protected final S currentState()

Returns the state as currently stored by Kalix.

Note that modifying the state directly will not update it in storage. To save the state, one must call {effects().updateState()}.

This method can only be called when handling a command or an event. Calling it outside a method (eg: in the constructor) will raise a IllegalStateException exception.

Throws:

IllegalStateException - if accessed outside a handler method

effects

protected final EventSourcedEntity.Effect.Builder<S> effects()