The advanced programming model

The basics around the Spring Cloud Stream programming model have been presented together with samples of point-to-point and publish/subscribe communication. Let's discuss some more advanced example features.

Producing messages

In all the samples presented in this chapter, we have sent orders through RESTful API for testing purposes. However, we may easily create some test data by defining the message source inside the application. Here's a bean that generates one message per second using @Poller and sends it to the output channel:

@Bean
@InboundChannelAdapter(value = Source.OUTPUT, poller = @Poller(fixedDelay = "1000", maxMessagesPerPoll = "1"))
public MessageSource<Order> ordersSource() {
    Random r = new Random();
    return () -> new GenericMessage<>(new Order(OrderStatus.NEW, (long) r.nextInt(5), Collections.singletonList((long) r.nextInt(10))));
}

Transformation

As you probably remember, account-service and product-service have been receiving...