Very few: No changes to core classes.
- The
UriUtility
class is no longer static so if you use this to calculate where file paths are, you need to inject it.
You can setup a content app in two ways either via a package.manifest file or by having a class that implements IContentAppFactory (and is registered via a composer)
you can control most things via the package.manifest file - registering via code just gives you slightly more control over when or when not to include your app.
the content app will show html/js from the app_plugins folder as defined by you
- Content App Intro https://umbraco.com/blog/umbraco-8-content-apps/
- Documentation https://our.umbraco.com/documentation/Extending/Content-Apps/