vukhoa30 / icommerce-demo

Distributed system

App features

• Search products with filters and sorts
• Store product searching statistics

App structure

DB Diagram

Sequence diagram for communication with RPC pattern and Direct Reply-to feature of RabbitMQ, describing the flow main-app request product-service for product data:

Self demo instructions

• Reprequisite: NodeJS, RabbitMQ server, PostgreSQL server, ts-node globally installed
• Configure database settings:
  • Create these databases manually if they don't exist:
    • For development: 'serviceproduct', 'servicestatistic'
    • For unit testing: 'testserviceproduct', 'testservicestatistic'
  • Go to product-service, create file named ".env", input the database username and password:
    • If you follow the method 1 bellow (recommended), input the 4 fields of DB username and password in "./ecosystem.config.js"
    • If you follow the method 2 bellow, Go to product-service, create file named ".env", input the database username and password and do the same for statistic-service:

DB_PASSWORD=<enter DB_PASSWORD here>
DB_USERNAME=<enter DB_USERNAME here>

• Install all dependencies: npm run ins
• Compile all typescript services: npm run compile
• Start app:
  • Method 1: run npm run startDev which using pm2
  • Method 2: run ts-node index.ts in 3 folders main-app, product-service, statistic-service (need to cd to the folder first) Notes: When running app, the DB migration and seed operations will be executed
• Run unit tests:
  • Go to product-service or statistic-service on terminal and run npm test
• Package for production:
  • Run npm run oneCommandPackage, a folder named "dist" will appear at root folder
  • Go to "dist", update environment variables in the file ecosystem.config.js (workaround for pm2)
  • The production app can be started with npm start now

Testing:

• Service unit tests: /services/.test.ts . Follow the steps in "Demo instructions" section to setup project and test.
• Using cURL (integration test):
  • Get products that are blue and ordered by descending ID (will add statistic to statistic-service): curl --request GET 'http://localhost:3000/products?filter=%7B%22color%22:%22Blue%22%7D&sort=%7B%22id%22:%22desc%22%7D'
  • Get product detail that has ID of 5 (will add statistic to statistic-service): curl --request GET 'http://localhost:3000/products/5'
  • Get products query statistics that are filtered by color: curl --request GET 'http://localhost:3000/statistic/products/query?filter=%5B%22color%22%5D'
  • Get product detail view statistics that has ID of 1: curl --request GET 'http://localhost:3000/statistic/products/detail-view?ids=%5B1%5D'

Source code description

Lib/frameworks

Express, RabbitMQ, knex, objectionjs, Jest, typescript, postgresql

Principles used, patterns, practices used

• Object oriented principle: using typescript with interfaces, classes and extends (inherit), implements (interface)
• Don't Repeat Yourself (DRY). For example, to make a RPC, project maintainer doesn't need to re-establish the whole RabbitMQ handling because it's already defined. He/she only needs to specify the data and the queue name for the function sendRPCData()
• Keep it simple, stupid (KISS): every function only does one certain thing
• Big design up front (BDUF): I design the app components, services, how it communite with each other(data flow), choosing the suitable tools in the beginning of the project.

Patterns used

• RPC (Remote Procedure Call) pattern.
• Publish/Subscribe pattern.

Best practices used

• Save testing requests in Postman and run it beside unit tests before every commit
• Using code naming over commenting

Services:

• Names and descriptions:
  • main-app: Is a REST API server, handle HTTP requests from client
  • product-service: Provide product operations including store and query for other services (only main-app at this point)
  • statistic-service: Provide statistic operations for other services, currently handling statistic for product querying for the main-app
• Service communications:
  • Using RabbitMQ with RPC pattern and Direct Reply-to feature, to main-app to request functions from product-service and statistic-service
  • Using RabbitMQ with publish/subscribe pattern to make main-app publish the events of product querying to statistic-service to store the data for marketing
• Service code structure example: main-app
  • configs: provide environment variables handling and constants
  • lib: provide main functions for the service including setting up HTTP server and RabbitMQ functions for service communication
  • routes: describe the REST server routing and it handling
  • index.ts: App start file
  • .env.example: environment variables template