I am trying to implement routing slip (EI Pattern) using Spring integration. The configuration I have done is
@Bean
@Transformer(inputChannel = "routingServiceChannel")
public HeaderEnricher headerEnricher() {
return new HeaderEnricher(Collections.singletonMap(IntegrationMessageHeaderAccessor.ROUTING_SLIP,
new RoutingSlipHeaderValueMessageProcessor("routingChannel2",
"routingChannel1")));
}
So when it reaches routingServiceChannel, it goes to routingChannel2 and then routingChannel1. But in my case it always throws an exception that it does not have a reply channel. when I set output channel, like
@Transformer(inputChannel = "routingServiceChannel", outputChannel=""xyzChannel)
Then then routing happens to xyzChannel instead of going to routingChannel2, and routingChannel1.
When I debugged the code in spring integration core, I stumbled with this code, In
class AbstractReplyProducingMessageHandler
protected final void handleMessageInternal(Message<?> message) {
Object result;
if (this.advisedRequestHandler == null) {
result = handleRequestMessage(message);
} else {
result = doInvokeAdvisedRequestHandler(message);
}
if (result != null) {
sendOutputs(result, message);
} else if (this.requiresReply) {
throw new ReplyRequiredException(message, "No reply produced by handler '" + getComponentName()
+ "', and its 'requiresReply' property is set to true.");
} else if (logger.isDebugEnabled()) {
logger.debug("handler '" + this + "' produced no reply for request Message: " + message);
}
}
Here in handle message method they obtain the routingSlip map and assigning it to the result. And
protected void produceOutput(Object reply, Message<?> requestMessage) {
MessageHeaders requestHeaders = requestMessage.getHeaders();
Object replyChannel = null;
if (getOutputChannel() == null) {
Map<?, ?> routingSlipHeader = requestHeaders.get(IntegrationMessageHeaderAccessor.ROUTING_SLIP, Map.class);
if (routingSlipHeader != null) {
Assert.isTrue(routingSlipHeader.size() == 1, "The RoutingSlip header value must be a SingletonMap");
Object key = routingSlipHeader.keySet().iterator().next();
Object value = routingSlipHeader.values().iterator().next();
Assert.isInstanceOf(List.class, key, "The RoutingSlip key must be List");
Assert.isInstanceOf(Integer.class, value, "The RoutingSlip value must be Integer");
List<?> routingSlip = (List<?>) key;
AtomicInteger routingSlipIndex = new AtomicInteger((Integer) value);
replyChannel = getOutputChannelFromRoutingSlip(reply, requestMessage, routingSlip, routingSlipIndex);
if (replyChannel != null) {
// TODO Migrate to the SF MessageBuilder
AbstractIntegrationMessageBuilder<?> builder = null;
if (reply instanceof Message) {
builder = this.getMessageBuilderFactory().fromMessage((Message<?>) reply);
} else if (reply instanceof AbstractIntegrationMessageBuilder) {
builder = (AbstractIntegrationMessageBuilder<?>) reply;
} else {
builder = this.getMessageBuilderFactory().withPayload(reply);
}
builder.setHeader(IntegrationMessageHeaderAccessor.ROUTING_SLIP,
Collections.singletonMap(routingSlip, routingSlipIndex.get()));
reply = builder;
}
}
if (replyChannel == null) {
replyChannel = requestHeaders.getReplyChannel();
}
}
Message<?> replyMessage = createOutputMessage(reply, requestHeaders);
sendOutput(replyMessage, replyChannel);
}
Instead of getting the routingSlip configuration from the reply, they are trying to get from the requestMessage. Am I missing something here? Are there any additional configuration that I need to set?