Apache Kafka used as Pub-Sub broker in NodeJS microservices for 1 million user messaging. Message Queue vs Pub-Sub explained with example implementation of Producer-Consumer system using Kafka.

Set up NodeJS backend & NextJS frontend with MongoDB local db using Docker. Created separate containers for each service, connected via docker-network & defined dependencies in docker-compose.yml file.

Connected NodeJS app to 2 databases (PostgreSQL & MongoDB) inside Docker containers. Used Docker Compose for easy setup. Repo available at https://github.com/fahadfahim13/node-pg-mongo-docker.git

NodeJS's Cluster module improves performance by launching multiple app instances on different CPU cores, utilizing multi-core processing & handling millions of requests in under 500ms.

NextJS & NestJS deployment on same server: Run NextJS (3001) & NestJS (8000) with PM2, use NginX as reverse proxy for routing. Configure NginX to forward requests to respective ports. Access APIs at your-domain-name/api and UI at your-domain-name/.