Understanding Microservices and Their Relationship with APIs

Microservices are small, single‑purpose services offered by a company, originating from a distributed computing architecture that connects many small services instead of a single large one, and they are delivered through Application Programming Interfaces (APIs).

How Microservices Work

Microservices extend the idea of a large monolithic service into independent functional units; for example, if Microsoft Word were split into microservices, one could handle a blank page, another spelling checks, and another formatting.

Kubernetes facilitates the coordination of containers, improving system reliability, scalability, and reducing management and resource costs, which drives the shift toward collections of small, cooperating services.

Examples of Microservices

Microservices are simple and role‑focused. Uber, for instance, builds separate services for passenger management, passenger web UI, invoicing, driver management, driver web UI, payment management, travel management, and notifications, all communicating via APIs.

Architectural diagrams can illustrate how a single microservice node communicates with another through an API, and as more services are added, the architecture can grow to the size of a small city, as shown in hypothetical Amazon and Netflix diagrams.

Microservices Depend on APIs

An API is a communication tool that enables one service to interact with another; by itself it does nothing until it is connected to a service or microservice, enabling functions such as Function‑as‑a‑Service, Machine‑Learning‑as‑a‑Service, and Software‑as‑a‑Service.

APIs allow microservices to be exposed to users without requiring software downloads, making them essential for the proper operation of a microservice architecture.

How APIs Work

APIs are versatile: they can be created on any containerized service, written in languages such as Java, Python, or Go, and deployed on any cloud provider.

APIs improve service availability and discoverability; many are RESTful and exposed via HTTP endpoints using standard methods like GET, POST, PUT, and DELETE. Alternatives include RPC and GraphQL.

Product‑level API endpoints are typically documented in a developer portal that explains the service purpose, data schema, and usage requirements, guiding developers on how to obtain API keys and interact with the service.

Good microservices always provide some form of API; if you want to use a microservice, you will need to create an API for it.

Original source: https://www.bmc.com/blogs/microservice-vs-api/