55 lines
1.7 KiB
Markdown
55 lines
1.7 KiB
Markdown
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---
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title: WebSockets
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---
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## WebSockets
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*Web Sockets* is a technology that allows you to create an interactive connection between a client and a server for exchanging data in real time. WebSockets allow you to work in two streams, which distinguishes this technology from HTTP.
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## How do WebSockets work?
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WebSockets do not need repeated calls to respond. It is enough to make one request and wait for a response. You can listen to the server, which will send the answer on readiness.
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## When can I use WebSockets?
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* Real-Time Applications
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* Chat application
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* IoT applications
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* Multiplayer games
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## When not to use WebSockets?
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WebSockets are already supported in 95% of browsers, but sometimes this technology is not required. For example, if you are creating a simple CMS where real-time functionality is not required.
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## WebSocket Example
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> Frontend (No need for an import, WebSockets are supported by [every major browser])
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```javascript
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const ws = new WebSocket('ws://localhost:3000');
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ws.onmessage = function(e){
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console.log('Message received from WebSocket');
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const parsedData = JSON.parse(e.data);
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handleData(parsedData);
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};
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ws.onopen = function(){
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console.log('Websocket open');
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}
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```
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> Backend (uses [ws](https://github.com/websockets/ws) and [express](https://expressjs.com/), the most common WebSocket client web framework for NodeJS)
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```javascript
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const SocketServer = require('ws').Server;
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const router = require('express').Router();
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const server = express()
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.use('/', router)
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.listen(3000, () => console.log('Listening on 3000'));
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const wss = new SocketServer({ server });
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```
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## Learn more
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[Official Mozilla API](https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API)
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