OAuth authentication for ews managed api

Question

Our EWS managed API application is currently using basic authentication with service account.

We are planning to change it to use OAuth authentication due to basic authentication won't work in 2020.

Will OAuth works with windows service in which there will be no user interaction? can we use OAuth Token from Azure AD when making EWS requests to read, update and delete user's calendar for on-prem exchange server and exchange online?

Answer 1

OAuth will work with a Windows service, using client credentials flow, AKA two-legged OAuth. Until Exchange 2019 appears, you can only do this with Exchange Online and Azure AD tokens.

One other thing: not only won't Basic Auth work in 2020, but I believe all of EWS will be deprecated in lieu of the Graph API by 2020.