Harry is a personal project exploring a microservices architecture to process returned items in a warehouse. It uses NATS for messaging and Centrifugo with WebSockets to notify fulfillment clients in real time, which helps unblock fulfillment items.

Architecture

Getting Started

Prerequisites

• Docker & Docker Compose
• Make

Quick Start

1. Start all services:

   make run-all

   This will automatically:

   • Start infrastructure services (PostgreSQL, NATS, Redis, Centrifugo)
   • Create databases and run migrations
   • Build and start all microservices

2. Generate Centrifugo token for WebSocket testing:

   docker exec -it centrifugo centrifugo gentoken -u 123722

   Copy the generated token for use in .env files and Postman.

Testing the Flow

1. Create test data in fulfillment database:

   INSERT INTO dbo.fulfillment
   (id, order_id, sku, quantity, status, fulfilled_at)
   VALUES(nextval('dbo.fulfillment_id_seq'::regclass), 10, 'sku-1234', 2, 'blocked', CURRENT_TIMESTAMP);
   
   SELECT id, order_id, sku, quantity, status, fulfilled_at
   FROM dbo.fulfillment;

2. Connect to WebSocket using Postman:

   Connect to: ws://localhost:8000/connection/websocket?cf_ws_frame_ping_pong=true

   Send these messages:

   {"id": 1, "connect": { "token": "<the_generated_token>"}}
   {"id": 2, "subscribe": {"channel": "fulfillment.order_unblocked"}}

3. Test the return item API:

   curl --location 'http://localhost:8080/return-item' \
   --header 'Content-Type: application/json' \
   --data '{
       "sku": "sku-5234",
       "quantity": 2
   }'

Available Commands

• make run-all - Build and start all services (detached)
• make dev-up - Build and start all services (foreground with logs)
• make stop-all - Stop all services
• make logs - View logs from all services
• make restart - Restart all services

Individual Service Commands

See the Makefile for individual service build/run commands for development.