The meaning of “small”

Many descriptions make parallels between the roles of individual microservices and chained commands on the unix command line:

$ ls | grep ‘service’ | sort -r

These unix commands each do different things. We use the commands without awareness of what language the commands are written in, or how big their codebase's are.

The size of a microservice is not related to the number of lines of code, it is instead describing its scope. The use of the word “small”, as applied to a microservice, essentially means that it is focused in purpose: it should do one thing, and do that one thing well.

Strategies for defining the scope of a service are discussed in detail in Chapter 2, “Creating Microservices in Java” on page 9.