I am attempting to write a service to take an action when a calendar event occurs. ie Appoint due in 15 min warning. Multiple users will need to be able to register with the service. I think Subscriptions are the what I need, although what "ChageType" to use to get an alert, I have not gotten to yet. Right now I get "Exchange Online resources are not supported for MSA requests." when I try to use this code. I am working against an outlook.com account.
GraphServiceClient graphClient = SDKHelper.GetAuthenticatedClient();
var subscription = new Microsoft.Graph.Subscription();
subscription.ChangeType = "updated";
subscription.ExpirationDateTime = System.DateTime.UtcNow.AddDays(1);
subscription.ClientState = System.Guid.NewGuid().ToString();
subscription.NotificationUrl = "https://mywebhook.azurewebsites.net/api/send/myNotifyClient"; // must be valid and able to verify?
subscription.Resource = "me/events";
var newsub = await graphClient.Subscriptions
.Request().AddAsync(subscription);