I had a small app that pulled my agenda (calendar events) from an Exchange server. But my company switched to office 365. I spent a few days trying to figure ou

I had a small app that pulled my agenda (calendar events) from an Exchange server. But my company switched to office 365. I spent a few days trying to figure out where I need to register and what API to use, etc so I can rewrite my app to work with Office 365. Now I don't have an app showing my agenda.