i++

Exercise web application where users can collectively increase the value of a counter on the server.

Server is in Go, Frontend in React. Communication is managed via WebSockets.

How to run this program locally

• Download the latest zip from the releases page
• Unzip in a directory of your choiche
• Source .env.local Run ./output/backend from the root of the project (or yarn start:local)
• Navigate to localhost:3000 in your browser

A minimal frontend is also exposed at http://localhost:3000/static/minimal.html

Development mode

• yarn develop:frontend
• yarn develop:backend

This will serve the web app under http://localhost:8080 (trough Webpack Dev Server) And the normal API + Static under http:////localhost:3000

Building

• yarn install
• yarn build:frontend
• yarn build:backend

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Requirements:

Go Server:

• Has an internal counter
• Serves static files
• Has POST endpoint to increase counter
• Has WebSocket to broadcast counter value
• Host address is ser via env variables

Frontend:

• React + Redux
• ES6 + JSX
• Reads value over WebSocket
• Has increase button that sends POST
• Looks nice, maybe with some CSS Framework
• Built with Webpack
• Has indicator for connection status
• Handles connection close gracefully

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Phases

0

• Set up frontend boilerplate
• Set up a simple static server
• Have a minimal working environment
• Setup releases including built files

1

• WebSocket Endpoint Handler
• WebSocket Connection Handler
• POST Endpoint
• POST Action
• UI

2

• Polish UI and server code
• Ensure portability
• Release V1

2.1

• Add reset endpoint and gui

3

• Refactor backend code for modularity
• Allow address configuration from env variables
• Seamlessly integrate change in frontend
• Display a websocket status indicator
• Handle disconnection gracefully

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Learning material

• Gorilla Chat Example
• The Little Go Book
• Concurrency patterns in Go