Node.js
What are microservices?
Learn the microservice architecture.
What is a microservice?
A microservice is a small, independent service that fulfills a single business capability. Instead of one big application (monolith), each business area becomes its own service: a user service, an order service, a payment service. Each service has its own lifecycle.
In a microservice architecture each service runs as a separate process and communicates via HTTP or a message queue. Advantages: independent deployment, separate scaling, technology choice flexibility. Disadvantages: distributed complexity, network latency, operational burden. Node.js fits microservices well with lightweight HTTP servers and an asynchronous nature. In this group you will learn the core patterns: communication, API gateway, service discovery and circuit breaker.
Monolith vs microservice
A monolith is an architecture where all functions live in a single application. In a microservice, each function is a separate service. A monolith is simple at first, but as it grows, deployment and scaling become harder.
Example: an e-commerce monolith holds user, order and payment code in one application. The microservice equivalent is three separate services. In a microservice each service deploys independently; a change in the order service does not affect the user service. But communication between services happens over the network, which adds latency and failure risk. This is why patterns like circuit breaker, retry and service discovery are needed. Good design balances monolith and microservice.
Exercise Write a user service skeleton
Import the express module. Create app. Define app.get("/users", (req, res) => res.json({ servis: "user-service" })). Print "Microservice ready" with console.log.
Show example solution
const express = require("express");
const app = express();
app.get("/users", (req, res) => res.json({ servis: "user-service" }));
console.log("Microservice ready");
Test yourself
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How do services communicate in a microservice architecture?
service A → HTTP → service B
- Directly via shared memory
- Via HTTP or a message queue
- Only by writing files
- Through a shared database
Show answer
Via HTTP or a message queue — Services communicate via HTTP or a message queue.
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Complete the service communication method
Services communicate via ____ or a message queue.
Show answer
Services communicate via HTTP or a message queue.
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Match each concept to its description
- microservice
- Small service doing one job
- monolith
- Single big application
- HTTP
- Service communication protocol
- message queue
- Async communication channel
Next lesson: Service communication
