For a project I'm working on, I need to subscribe to Exchanges server side events. Each time a calendar appointment is created, whether from Outlook or the web ui, I need to access the appointment data (date & time, participants, location, etc) so I can send it to an internal reporting service.
I know you can do this in Outlook with an addin, but can you do this server side as well? Not everybody will use Outlook, there's the web ui and other internal projects that can create appointments directly via EWS.
Yes, you can use EWS to receive notifications when appointments are created/changed. It works very well. This also works for Office 365, and for changes made via any Exchange client, such as OWA, not just Outlook.
https://msdn.microsoft.com/en-us/library/office/dn458791%28v=exchg.150%29.aspx