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The agreed-upon definition of an application boundary also allows to take a close look at the APIs that are exposed by each application component, for simplicity identified as a microservice. Most microservices components make their capabilities available via an interface such as RESTful HTTP/JSON based APIs. Just as the number of microservices components on the network increases, so does the number of exposed APIs on those components. See Figure 4-14 on page 117. 

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How can consumers find the APIs they want from the overwhelming set available? Which are APIs that should be re-used in other contexts? 

Ideally microservices components are completely independent. But, in reality, some are really used only in the narrow context of an application. And some others are intended for much 

