org.axonframework.commandhandling

Annotation Type CommandHandler

@Documented
 @Retention(value=RUNTIME)
 @Target(value={METHOD,CONSTRUCTOR,ANNOTATION_TYPE})
 @MessageHandler(messageType=CommandMessage.class)
public @interface CommandHandler

Marker annotation to mark any method on an object as being a CommandHandler. Use the AnnotationCommandHandlerAdapter to subscribe the annotated class to the command bus.

Alternatively, the annotations may be placed on an Aggregate members, in which case the AggregateAnnotationCommandHandler can be used to subscribe the handlers to the command bus. When the annotation appears on an Aggregate root's constructor, that command will cause a new aggregate to be created and stored in the repository provided with the AggregateAnnotationCommandHandler. If a non-root entity of the Aggregate is to handle a command, the field declaring that entity must be annotated with AggregateMember. Note that the CommandHandler annotation may not be placed on a non-root Entity's constructor.

The annotated method's first parameter is the command handled by that method. Optionally, the command handler may specify a second parameter of type UnitOfWork. The active Unit of Work will be passed if that parameter is supplied.

Since:

0.5

Author:

Allard Buijze

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
String	commandName The name of the Command this handler listens to.
Class<?>	payloadType The type of payload expected by this handler.
String	routingKey The property of the command to be used as a routing key towards this command handler instance.

Element Detail

commandName

public abstract String commandName

The name of the Command this handler listens to. Defaults to the fully qualified class name of the payload type (i.e. first parameter).

Returns:

The command name

Default:

""

routingKey

public abstract String routingKey

The property of the command to be used as a routing key towards this command handler instance. If multiple handlers instances are available, a sending component is responsible to route commands with the same routing key value to the correct instance.

Returns:

The property of the command to use as routing key

Default:

""

payloadType

public abstract Class<?> payloadType

The type of payload expected by this handler. Defaults to the expected types expresses by (primarily the first) parameters of the annotated Method or Constructor.

Returns:

the payload type expected by this handler

Default:

java.lang.Object.class