---
categories:
    - Web
    - JS
    - WS
cover: wsjsws.jpg
cover_alt: idk yet what will the cover be
date: 17/02/2023
description: Websocket workshop for multiplayer drawing
git: https://git.xpub.nl/kamo/drw
slug: ws-js-ws
title: ws js ws
---


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  <source src="flyer.mp4" type="video/mp4">
</video>


### Contents

A one-day workshop about real-time interactions with websockets! 

Starting from a simple drawing app, we are going to explore how to create multiplayer online applications that deal with inputs coming from multiple users connected at the same time. 

No previous knowledge nedeed, but some HTML & CSS & JS will come handy. 
Bring your own laptop and lunch! Snacks and coffee will be offered! 

### When and where

Friday 24th, from 11:00 to 17:00  
XPUB Studio, 4th floor etc

### Program


- 11:00 - Intro & demo of [drw](https://hub.xpub.nl/soupboat/drw/)
- 11:30 - How does it work
- 12:00 - Step by step installation following [drw documentation](https://git.xpub.nl/kamo/drw)
- 12:30 - Examples & brainstorm for projects

- 13:00 - Lunch break

- 14:00 - Prototyping
- 16:00 - Upload online
- 16:30 - Try out and presentation

## Intro

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DRW is a small app for multiplayer drawing in real time.
To draw connect to --> [https://hub.xpub.nl/soupboat/drw](https://hub.xpub.nl/soupboat/drw)

It works with multiple sources, but also multiple destinations.

The same drawings can be displayed on different places! _(such as this page)_

Open [https://hub.xpub.nl/soupboat/drw/destination](https://hub.xpub.nl/soupboat/drw/destination) and send some drawings.
Try to navigate to [https://hub.xpub.nl/soupboat/drw/wander](https://hub.xpub.nl/soupboat/drw/wander) to see a different mode.

## How does it work

![ping pong is my passion](https://git.xpub.nl/kamo/drw/raw/branch/main/img/pingpong.jpg)  

### Websockets

DRW is like ping pong! 

Sources and destinations send each other small messages using a protocol called [websockets](https://javascript.info/websocket).

Once a websocket connection is open, they can communicate in both directions.
From the source to the destination and the other way around!

Websockets are great for applications that require continous data exchange, such as chat and games.

### DRW Architecture

Two types of entities:
- Clients
- Server

Every client is connected to the server, either as a source or as a destination.

Depending on their role, clients send different kinds of messages to the server.
 
The server manages the flow of websocket messages, taking care to deliver the right message to the right client.

### Message

In this app, a message is a simple text string.  
It looks like

```
{"type": "test", "data": "this is my test message"}
```

Here the message has two properties: `type` with value _test_, and `data` with value _this is my test message_.

Using the [JSON](https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Objects/JSON) format, the message contents can be accessed easily. 


```
// Transform the string message into a Javascript object
let message = JSON.parse({"type": "test", "data": "this is my test message"})

// Access the contents of the message
console.log(message.type)
// test

console.log(message.data)
// this is my test message
```

(`console.log()` in Javascript is like `print()` in Python)

## Installation

Step to step process to install DRW on your machine. 
Find the documentation on --> [Gitea](https://git.xpub.nl/kamo/drw#setup)

What do you need:

- A terminal
- [git](https://git-scm.com/downloads)
- [Node.js](https://nodejs.org/en/download/)

For later on
- A code editor (sublime, atom, vscode, etc)