Mapping Office365 REST Calendar IDs to EWS CalendarItem IDs

Question

Using Exchange push notifications I\'ve been creating a service that syncs over calendar data from Office365 users. I\'ve been using a combination of the Office365 Calendar REST

Answer 1

So it turns out that my IDs mismatched due to subscribing to EWS push notifications via the Exchange2007 version. Exchange2007_SP1 and beyond have compatible EwsIds with each other so this includes Office365.

Replacing - characters with / and _ characters with + allows me to properly make calls to Office365 API resources.

Finally, when making a call to get calendars, the API is actually returning Message item types that live under the Common Views folder. So when attempting to use these IDs for subscriptions, the EWS API will complain that I've sent it ItemIDs and not a Folder ID.

Thankfully I've found that making a request to the REST API via GET /calendars/ews_folder_id actually works once you properly translate the ID to a URI safe type (see above conversion).