Building Event-Driven Microservices

Chapter 9. Microservices Using Function-as-a-Service

Functions-as-a-Service (FaaS) is a “serverless” solution that has become increasingly popular in recent years. FaaS solutions enable individuals to build, manage, deploy, and scale application functionality without having to manage infrastructural overhead. They can provide significant value in event-driven systems as a means of implementing simple to moderately complex solutions.

A function is a piece of code that is executed when a specific triggering condition occurs. The function starts up, runs until completion, and then terminates once its work is completed. FaaS solutions can easily scale the number of function executions up and down depending on load, providing close tracking for highly variable loads.

It may be helpful to think of a FaaS solution as a basic consumer/producer implementation that regularly fails. A function will always end after a predetermined amount of time, and any connections and state associated with it will go away. Keep this in mind as you design your functions.

Designing Function-Based Solutions as Microservices

FaaS solutions may comprise many different functions, with the sum of their operations constituting the solution to the business bounded context. There are many ways to create function-based solutions, far more than this chapter can cover, but there are a few general design principles that will help guide you through the process.

Ensure Strict Membership to a Bounded Context

The functions ...