Description

Project created by Nestjs CLI

$ npx @nestjs/cli new sportradar-coding

Installation

$ npm install

Running the app

# development
$ npm run start

# watch mode
$ npm run start:dev

Test

# unit tests
$ npm run test

# e2e tests
$ npm run test:e2e

# test coverage
$ npm run test:cov

Solution Notes

The API is designed with the following considerations:

• for simplicity, simulation structure is very simple
  • no score history
  • time when score occured is not tracked
  • setInterval provides >= intervalMs delay (depends on how busy process is, etc). No rounding implemented to provide exactly intervalMs delays
• single connection supports multiple simulations
  • in order to run multiple simulations "real" clientId should be use for rate limiter
• no broadcasting supported to notify multiple clients
• rate-limiter uses socket.id to identify client for simplicity
  • clientId can be passed as query / taken from auth token
  • can be scaled by replacing storageService with Redis implementation, for example
• every simulation has it's own timer
  • it can be a problem if there are a lot simulations running
  • another approach is to have single independent timer and update simulations on every tick
• e2e test timeout set to 100 seconds
  • better approach is to override default simulation settings and speed up the tests
• simple client implemented for testing purposes (see client folder)

Out of scope

• Cross-server event replication
• Hash-based balancing
• Auth
• Broadcast
• Data Persistance
• Unified API response structure
• Possibility to configure the simulation (useful for e2e)