The publish/subscribe model

The main motivation for creating a Spring Cloud Stream project is, in fact, support for a persistent publish/subscribe model. In the previous sections, we have discussed point-to-point communication between microservices, which is just an additional feature. However, the programming model is still the same, irrespective of whether we decided to use a point-to-point or publish/subscribe model.

In publish/subscribe communication, the data is broadcast through shared topics. It reduces the complexity of both the producer and the consumer, and allows new applications to be easily added to the existing topology without any changes in flow. This can be clearly seen in the last-presented sample of the system, where we decided to add the second application that has consumed events produced by the source microservice. In comparison to the initial architecture, we had to define custom message channels dedicated for each of the target applications. With direct communication...