Summary
This module explained the how and why of installation and upgrade code, your responsibilities, and where to find documentation and examples on how to implement it.
Keep in mind that the principle of keep it simple also applies here. Don't create installation code that performs many complex and long operations. Don't include complex code that connects to external services. Make sure you keep this process simple, fast, and straightforward. You don't want your application to break during installation or upgrade, so make sure this process works, is fast, and also thoroughly tested.