Rolling updates out automatically?

Hi, here are some basics on how to automatic update a program.

1. Store current version in a file/database
2. Make a GET request to your server with current version
2.1 Download a .zip file from your server, if there are a new version.
2.2. Unpack and replace all files
3. Profit!

As for an example, just look at some open source projects like Wordpress. They support automatic update.