devhulk / go-websockets

Golang Websockets Front-End Starter Project (Chat App)

• I'm not using any framework for the front end just pure HTML, CSS, and Javascript.
• Golang is being used to serve the 'web' directory which contains all our front-end code.
• The web socket portion of the app is using Gorilla Websockets (yay for them being maintained again!)

Front-End Code -> /web

Backend Code -> *.go files

Run the project with (If you change any of the *.go you will need to quit and re-run this command):

go run *.go

Then go to localhost:8080/wechat/ in your browser of choice.

What you can learn from this project

Frontend

• The web/script.js file has examples of manipulating CSS and HTML with Javascript (DOM Manipulation)
• The web/styles.css has some good css examples. (Can find what classes are used in the script.js file?)
• The web/index.html contains our page scaffolding. (Can tell me what external css library I'm using?)

Backend

• main.go will show you how to set up a couple API endpoints. One for static file serving and one to handle the websocket connections.
• client.go will introduce you to an example of the "client" portion of the "client - server model" using websockets as the protocol. This will also lay the foundation for golang channels which is an important part of concurrent processing in golang. Because Websockets is bi-directional we need to be able to process messages as events not just step by step actions that happen one after the other.
• hub.go The hub and client will show you channels and go routines in action. The hub keeps track of all "client" connections and broadcasts messages sent by a single clients to all other clients.

Resources

• What are Websockets?

  "Historically, creating web applications that need bidirectional communication between a client and a server (e.g., instant messaging and gaming applications) has required an abuse of HTTP to poll the server for updates while sending upstream notifications as distinct HTTP calls [RFC6202].

  This results in a variety of problems:

  o The server is forced to use a number of different underlying TCP connections for each client: one for sending information to the client and a new one for each incoming message.

  o The wire protocol has a high overhead, with each client-to-server message having an HTTP header.

  o The client-side script is forced to maintain a mapping from the outgoing connections to the incoming connection to track replies."