Overview of My Submission

This week, I built Collanvas, a collaborative drawing platform with no login required, and where every user has access to only one color.

I created Collanvas for various reasons, one of them is brainstorming. Go draw the next big thing!

You can also use Collanvas for art. With one color per person, each one can focus on a specific part of the design.

And of course, you can also play games on Collanvas. With the chat feature, play draw-and-guess with your mates until your energy is full again.

Submission Category:

MERN Mavericks

Language Used

JS/TS/Node.js

Link to Code

Additional Resources / Info

How did I build Collanvas? Let's get technical.
Were storing two JSON documents per room:

1. The first one is strokes, a collection of every stroke on the canvas. We collect the stroke color, thickness, type, and the set of points that make it up. Type dictates whether the stroke is in pen-mode or eraser-mode.

1. Next and last document is messages, an array of every sent message in the room. We collect the user-name, user-color and the content of the message.

Were using Redis Insight to inspect our database and confirm our data modeling strategy.

But when should we start saving data in these documents? Well, firstly, when the user lifts their pointer from the canvas, we add the drawn stroke to the Redis JSON store with the arrAppend command.

Lastly, when the user sends a new message, thats when we save their thoughts to the document with the same command.

Okay, but why are we saving all this data? Well, when the user first joins a room, we get them started by reading every stroke and message from the database and inserting them in their website.

Sounds good, but how do we update Collanvas for every user in real-time? Well, were using web-sockets to create a channel of communication between the server and the browser. When the server receives information that, say, a new message just got sent, it will feed that information back into the browser and it will be added without reloading the page.

But how do we make different socket connections talk with each other? Redis solves this problem through their Publisher-Subscriber service. Each connection subscribes and publishes to its own two channels of messages and strokes, relaying all information to the browser.

• Check out Redis OM, client libraries for working with Redis as a multi-model database.
• Use RedisInsight to visualize your data in Redis.
• Sign up for a free Redis database.