Building Event-Driven Microservices

Chapter 10. Basic Producer and Consumer Microservices

Basic producer and consumer (BPC) microservices ingest events from one or more event streams, apply any necessary transformations or business logic, and emit any necessary events to output event streams. Synchronous request-response I/O may also be a part of this workflow, but that topic is covered in more detail in Chapter 13. This chapter focuses strictly on event-driven components.

BPC microservices are characterized by the use of basic consumer and producer clients. Basic consumer clients do not include any event scheduling, watermarks, mechanisms for materialization, changelogs, or horizontal scaling of processing instances with local state stores. These capabilities typically belong only to more full-featured frameworks, which Chapters 11 and 12 will discuss in more depth. While it is certainly possible for you to develop your own libraries to provide these features, doing this is quite beyond the scope of this chapter. Thus, you must carefully consider if the BPC pattern will work for your business requirements.

Producer and consumer clients are readily available in most commonly used languages, lowering the cognitive overhead in getting started with event-driven microservices. The entire workflow of the bounded context is contained within the code of the single microservice application, keeping the responsibilities of the microservice localized and easy to understand. The workflow can also easily be wrapped into one ...