Abstracting Spring Cloud Stream Producer and Consumer code - spring-integration

Question

I have a Service that is Producing and Consuming messages from different Spring Cloud Stream Channels (bound to EventHub/Kafka topics). There are several such Services which are setup similarly.
The configuration looks like below
public interface MessageStreams {
String WORKSPACE = "workspace";
String UPLOADNOTIFICATION = "uploadnotification";
String BLOBNOTIFICATION = "blobnotification";
String INGESTIONSTATUS = "ingestionstatusproducer";
#Input(WORKSPACE)
SubscribableChannel workspaceChannel();
#Output(UPLOADNOTIFICATION)
MessageChannel uploadNotificationChannel();
#Input(BLOBNOTIFICATION)
SubscribableChannel blobNotificationChannel();
#Output(INGESTIONSTATUS)
MessageChannel ingestionStatusChannel();
}
#EnableBinding(MessageStreams.class)
public class EventHubStreamsConfiguration {
}
The Producer/Publisher code looks like below
#Service
#Slf4j
public class IngestionStatusEventPublisher {
private final MessageStreams messageStreams;
public IngestionStatusEventPublisher(MessageStreams messageStreams) {
this.messageStreams = messageStreams;
}
public void sendIngestionStatusEvent() {
log.info("Sending ingestion status event");
System.out.println("Sending ingestion status event");
MessageChannel messageChannel = messageStreams.ingestionStatusChannel();
boolean messageSent = messageChannel.send(MessageBuilder
.withPayload(IngestionStatusMessage.builder()
.correlationId("some-correlation-id")
.status("done")
.source("some-source")
.eventTime(OffsetDateTime.now())
.build())
.setHeader("tenant-id", "some-tenant")
.build());
log.info("Ingestion status event sent successfully {}", messageSent);
}
}
Similarly I have multiple other Publishers which publish to different Event Hubs/Topics. Notice that there is a tenant-id header being set for each published message. This is something specific to my multi-tenant application to track the tenant context. Also notice that I am getting the channel to be published to while sending the message.
My Consumer code looks like below
#Component
#Slf4j
public class IngestionStatusEventHandler {
private AtomicInteger eventCount = new AtomicInteger();
#StreamListener(TestMessageStreams.INGESTIONSTATUS)
public void handleEvent(#Payload IngestionStatusMessage message, #Header(name = "tenant-id") String tenantId) throws Exception {
log.info("New ingestion status event received: {} in Consumer: {}", message, Thread.currentThread().getName());
// set the tenant context as thread local from the header.
}
Again I have several such consumers and also there is a tenant context that is set in each consumer based on the incoming tenant-id header that is sent by the Publisher.
My questions is
How do I get rid of the boiler plate code of setting the tenant-id header in Publisher and setting the tenant context in the Consumer by abstracting it into a library which could be included in all the different Services that I have.
Also, is there a way of dynamically identifying the Channel based on the Type of the Message being published. for ex IngestionStatusMessage.class in the given scenario

Answer 1

To set and tenant-id header in the common code and to avoid its copy/pasting in every microservice you can use a ChannelInterceptor and make it as global one with a #GlobalChannelInterceptor and its patterns option.
See more info in Spring Integration: https://docs.spring.io/spring-integration/docs/5.3.0.BUILD-SNAPSHOT/reference/html/core.html#channel-interceptors
https://docs.spring.io/spring-integration/docs/5.3.0.BUILD-SNAPSHOT/reference/html/overview.html#configuration-enable-integration
You can't make a channel selection by the payload type because the payload type is really determined from the #StreamListener method signature.
You can try to have a general #Router with a Message<?> expectation and then return a particular channel name to route according that request message context.
See https://docs.spring.io/spring-integration/docs/5.3.0.BUILD-SNAPSHOT/reference/html/message-routing.html#messaging-routing-chapter