Service, API, Component

What Are They, How Do They Relate

Internal and External API

These terms are so commonly used they are like the conceptual floor we are standing on in discussing or even thinking about software.

First off, let’s make some observations, from the profane to the profound.

The Fairly obvious:

• A service is any remotely available resource that can respond to requests.
• An API is a software interface that can defines how a software component handles requests and responses.
• A component is a discrete element of software

The Less Obvious:

• Every service is an API.
• Applications are comprised of interacting components

The Profound:

• Every API defines a component.
• A component, to the outside world, is its API
• A component, on the inside, is the arrangement of other API

Two Types of API

There are two primary types of API:

• Remote API: Requests/Response cross the network
• Local API: Request/Response are handled via internal call