HTML5/Canvas - Save Base64 image to server (replacing current image)

[ulagerket]

I am currently experimenting with the HTML5 Canvas.I currently made a simple little painting app where you can draw lines and what not.I made it so I can save the image in base64. withvar dataUrl = document.getElementById('your-canvas').toDataURL();I was wondering if it is possible to take that image, and save it to my server (or anywhere) replacing/overwriting an image that is already there.The goal of this is to have the saved image as the background for the canvas. Then every time someone draws on the canvas and clicks save, it saves their drawing as the background image so the next person who goes on it can see what the last person drew.Basically a public internet whiteboard.Can someone tell me if this is possible, and point me in the right direction (code languages, tutorials, etc.)?Thanks.