✨ Example of a chat application using clean architecture ✨

Discover the magic of clean architecture.

See: The Clean Architecture

In this example, when using Angular or NestJs, we only utilize the necessary features such as Dependency Injection (DI), modules ... The frameworks/lib used as a tool.

Starting with Test-Driven Development (TDD) will be easy, and our business rules can be tested without relying on the UI, database, web server, or any other external elements.

This example runs in two environments:

• In-memory: Used as an integration test for the full system and runs inside Angular (page: /chat/multi).
• Network: Uses HTTP and WebSocket, allowing the system's components to be easily split between client and server.

In this example, we use a native HTML/CSS view and another one using material-components. The UI can be easily changed without affecting the rest of the system. (Note: The API can also be seen as another kind of UI output.)

In this example, we use an in-memory database as a mock and MongoDB. However, you can easily swap it out for MySQL, Cassandra, Oracle, or any other database. Your business rules are not tightly coupled to the database.

In this example, all business rules are decoupled from the outside world. See the dependency graph Dependencies Graph

https://stackblitz.com/github/moez-sadok/chat-clean-architecture

npm i

npm run start

npm run start:api

Version 1: Full in-memory angular app as main (no need to run the back-end api)

• http://localhost:4200/chat/multi

Version 2: With client/server (websockt/http), open in different private tabs

• http://localhost:4200/chat/user/1
• http://localhost:4200/chat/user/2

npm run dep-graph

Many other tools harness the power of port/adapter architecture. For instance, Redis enables the creation and connection of a multi-chat server to support millions of connected users with just three lines of code.

See also: https://socket.io/docs/v4/redis-adapter/

https://docs.nestjs.com/websockets/adapter

To install Redis, please check the official Redis website and see also NestJS WebSocket Adapter documentation.

• Uncomment redis adapter code inside the main.ts of chat-server-main-api

  // const redisIoAdapter = new RedisIoAdapter(app);
  // await redisIoAdapter.connectToRedis();
  // app.useWebSocketAdapter(redisIoAdapter);

• Run redis server inside the cmd

redis-server

Using Nx console vs code extension or cli:

Generate nest app:

npx nx generate @nrwl/nest:application chat/chat-server-main-api --frontendProject chat-chat-client-main-ng

Generate lib:

npx nx generate @nrwl/workspace:library chat/entreprise-business-rules/notifiyer
npx nx generate @nrwl/workspace:library chat/application-business-rules/network
npx nx generate @nrwl/workspace:library chat/adapters/network

node tests/bench/send-message-bench-test.js or autocannon -c 10 -a 1000 -m POST http://localhost:3333/api/send-message --header 'Content-Type: application/json' --body '{ "roomId": "0", "userId": "1", "message": "perf message" }'