Spring-Integration Simple Bridge with annotation

1
votes

how can i define a simple bridge that just bridges from one directChannel to another with java annotations

in xml one can do it like this (taken from http://docs.spring.io/spring-integration/reference/html/messaging-channels-section.html)

<int:bridge input-channel="input" output-channel="output"/>

with annotations i would have expected the definition to look like something this 

@Bean
@BridgeFrom("inboundChannel")
@BridgeTo("outboundChannel")
public MessageChannel bridge() {
    return new DirectChannel();
}

but this gives me the error

IllegalArgumentException: '@BridgeFrom' is eligible only for 'MessageChannel' '@Bean' methods

any suggestions how i would translate the above xml-definition into a java-config-definition?

2
spring-integration

2 Answers

3
votes

It should be

@Bean
@BridgeTo("output")
public MessageChannel input() {
    return new DirectChannel();
}

or

@Bean
@BridgeFrom("input")
public MessageChannel output() {
    return new DirectChannel();
}

Your work-around is ok, but a little less efficient.

EDIT

If you want to bridge two channels, the configuration for which you don't have control, or you want to bridge between "library" configs in different ways, this is a more efficient version of what you have...

@Bean
@ServiceActivator(inputChannel="inboundChannel")
public MessageHandler bridge() {
    BridgeHandler handler = new BridgeHandler();
    handler.setOutputChannelName("outboundChannel");
    return handler;
}

Note that the output channel goes on the handler, not the service activator annotation. See here for this style of configuration.

0
votes

i found a workaround using a @ServiceActivator, but i'm not sure if that is 100% equivalent. 

@ServiceActivator(inputChannel = "inboundChannel", outputChannel = "outboundChannel")
public Message<?> bridge(Message<?> m) {
    return m;
}