Node Pub/Sub

Study project focused on Node.js with TypeScript and event-driven architecture using RabbitMQ.

Features

• Class-Based Architecture: Robust implementation of abstract Publishers and Consumers.
• RabbitMQ: Full integration with exchanges, queues, and dead letter queues.
• REST API: Express server to create orders via HTTP.
• Automation Scripts: Tools for load testing and manual pub/sub.
• Tutorials: Practical examples

Prerequisites

1. Node.js
2. Docker & Docker Compose (to run RabbitMQ)

Installation

1. Install dependencies:

   npm install

2. Start RabbitMQ:

   docker-compose up -d

How to Use

1. Hello World

Quick test to verify RabbitMQ connection.

• Receive messages:

  npm run hello:receive

• Send messages:

  npm run hello:send

2. Work Queues

Distribute time-consuming tasks among multiple workers.

• Start Worker:

  npm run work:worker

• Send New Task:

  npm run work:new_task -- "My Task..."

• Send Multiple Tasks:

  npm run work:send_tasks

3. Publish/Subscribe

Broadcast messages to multiple consumers (logging).

• Receive Logs:

  npm run log:receive

• Emit Log:

  npm run log:emit -- "Log info..."

4. Routing

Subscribe only to a subset of messages (e.g. only critical errors).

• Receive Logs (info, warning):

  npm run log:receive:direct -- info warning

• Emit Log (error):

  npm run log:emit:direct -- error "Run. Run. Or it will explode."

5. Topics

Receive messages based on a pattern (topics).

• Receive (all logs):

  npm run log:receive:topic -- "#"

• Receive (kernel logs):

  npm run log:receive:topic -- "kern.*"

• Emit Log:

  npm run log:emit:topic -- "kern.critical" "A critical kernel error"

6. RPC (Remote Procedure Call)

Request/reply pattern for remote procedure calls.

• Start Server:

  npm run rpc:server

• Send Request:

  npm run rpc:client -- <number>

  Example: npm run rpc:client -- 30

7. Order System

Complete simulation of an order creation flow.

A. Run the Consumer

Starts the service listening to the order.created queue.

npm run order:consume

B. Publish an Order (Manual)

Sends a single order event to the queue.

npm run order:publish

C. Load Test (Bulk)

Publishes multiple orders at once to test processing.

# Publishes 1000 orders (default)
npm run order:bulk

8. REST API

Starts the Express server to receive orders via HTTP.

1. Start the API:

   npm run api

2. Create an order (curl example):

   curl -X POST http://localhost:3000/api/orders \
        -H "Content-Type: application/json" \
        -d '{"orderId": "123", "total": 99.90, "userId": "user_01"}'

Monitoring

Access the RabbitMQ management dashboard:

• URL: http://localhost:15672
• User: guest
• Password: guest

Project Structure

• src/api: Express server.
• src/consumer: Consumer logic (Base + Implementations).
• src/producer: Publisher logic (Base + Implementations).
• src/events: Event type definitions and interfaces.
• src/infra: RabbitMQ configuration and client.
• src/scripts: Utility scripts for manual testing.
• src/tutorials: Introductory examples.

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Project for study purposes.