org.axonframework.queryhandling.registration

Interface DuplicateQueryHandlerResolver

All Known Implementing Classes:

FailingDuplicateQueryHandlerResolver, LoggingDuplicateQueryHandlerResolver

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 DuplicateQueryHandlerResolver

Functional interface towards resolving the occurrence of a duplicate query handler being subscribed. As such it ingests two MessageHandler instances and returns a list with the wanted handlers

Since:

4.6.0

Author:

Mitchell Herrijgers

Method Summary

Modifier and Type	Method and Description
List<QuerySubscription<?>>	resolve(String queryName, Type responseType, List<QuerySubscription<?>> registeredHandlers, QuerySubscription<?> candidateHandler) Chooses what to do when a duplicate handler is registered, returning the handlers that should be selected for query handling, or otherwise throwing an exception to reject registration altogether.

Method Detail

resolve

List<QuerySubscription<?>> resolve(String queryName,
                                   Type responseType,
                                   List<QuerySubscription<?>> registeredHandlers,
                                   QuerySubscription<?> candidateHandler)

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

Parameters:

queryName - The name of the query for which the duplicate was detected

registeredHandlers - the MessageHandler instances already registered with the Query Bus

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

Returns:

the resolved MessageHandler instances. It is up to the implementation to discard implementations already in the list

Throws:

RuntimeException - when registration should fail