org.axonframework.commandhandling

Interface DuplicateCommandHandlerResolver

All Known Implementing Classes:

FailingDuplicateCommandHandlerResolver, LoggingDuplicateCommandHandlerResolver

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface DuplicateCommandHandlerResolver

Functional interface towards resolving the occurrence of a duplicate command handler being subscribed. As such it ingests two MessageHandler instances and returns another one as the resolution.

Since:

4.2

Author:

Steven van Beelen

Method Summary

Modifier and Type	Method and Description
MessageHandler<? super CommandMessage<?>>	resolve(String commandName, MessageHandler<? super CommandMessage<?>> registeredHandler, MessageHandler<? super CommandMessage<?>> candidateHandler) Chooses what to do when a duplicate handler is registered, returning the handler that should be selected for command handling, or otherwise throwing an exception to reject registration altogether.

Method Detail

resolve

MessageHandler<? super CommandMessage<?>> resolve(@Nonnull
                                                  String commandName,
                                                  @Nonnull
                                                  MessageHandler<? super CommandMessage<?>> registeredHandler,
                                                  @Nonnull
                                                  MessageHandler<? super CommandMessage<?>> candidateHandler)

Chooses what to do when a duplicate handler is registered, returning the handler that should be selected for command handling, or otherwise throwing an exception to reject registration altogether.

Parameters:

commandName - The name of the Command for which the duplicate was detected

registeredHandler - the MessageHandler previously registered with the Command Bus

candidateHandler - the MessageHandler that is newly registered and conflicts with the existing registration

Returns:

the resolved MessageHandler. Could be the registeredHandler, the candidateHandler or another handler entirely

Throws:

RuntimeException - when registration should fail