I would like to manage Exchange ActiveSync devices (add device, remove, list devices, add policies to devices etc) via external rest api. This means that I would like to execute cmdlets commands for exchange (such as described here https://technet.microsoft.com/en-us/library/dn641223(v=exchg.160).aspx) via external api (e.g SOAP, REST) and not internally from the machine.
Is this possible, or do I have to implement an API on the machine?
The Exchange Management Shell cmldets can be executed via Remote Powershell from Exchange 2010 up so you can put your REST code on any WebServer that itself can establish a Remote Powershell connection back to the Target Exchange Server. Using that method avoids needing to make any changes to the Exchange Server.