Spring integration flow: perform task within flow

Question

hopefully this one is the last question I'm asking on spring integration.

Faced following problem: at the end of pretty long IntegrationFlow dsl sheet there is a code:

   return IntegrationFlows.
   //...
       .enrichHeaders(headerEnricherSpec -> headerEnricherSpec.header("jms_replyTo", responseQueue(), true)) // IntegrationMessageHeaderAccessor.CORRELATION_ID is not acceptable though message came from outgoingGateway of another application with this header been set
       .handle(requestRepository::save)
       .handle(
            Jms.outboundAdapter(queueConnectionFactory()).destination(serverQueue())
       )
       .get();

The problem is that after some code like requestRepository::save handlers chain becomes broken. This trick only works if there is a gateway passed in as a handler parameter.

How can I overcome this limitation? I think that utilizing wireTap here will not make a deal because it is asynchromous. Here, actually, I save message to store it's jms_replyTo header and replace it with saved one after corresponding reply comes back from server (Smart Proxy enterprise integration pattern).

Any suggestions please?

Answer 1

Not sure why do you say "the last question". Are you going to give up on Spring Integration? :-(

I guess your problem there with the next .handle() because your requestRepository::save is one-way MessageHandler (the void return from the save() method). Or your save() returns null.

The IntegrationFlow is a chain of executions when the next one will be called after the previous with its non-null result.

So, share your requestRepository::save, please!

UPDATE

Neither did help declaring MessageHandler bean as a (m) -> requestRepository.save(m) and passing it into handle(..) method as a param.

Yeah... I would like to see the signature for your requestRepository::save.

So, look. Using method reference for the .handle() you should determine your scenario. If you do one-way handle with the flow stop, there is enough to follow with the org.springframework.messaging.MessageHandler contract. with that you method signature should be like this:

public void myHandle(Message<?> message)

If you'd like to go ahead with the flow you should return anything from your service method. And that result becomes the payload for the next .handle(). In this case your method should follow with the org.springframework.integration.dsl.support.GenericHandler contract. Your method signature may look like:

public Bar myHandle(Foo foo, Map<String, Object> headers)

That's how the method reference works for the .handle().

You should understand how this method chain style works. The output of the previous method is an input of the next. In this our case we protect the flow from the dead code, like MessageHandler with void return, but there is the next flow member. That's why you see This is the end of the integration flow. error.