This service broker makes use of Microsoft's EWS Managed API (https://github.com/OfficeDev/ews-managed-api) to make web service calls to Exchange to grab or update the out-of-office settings for the current user.
Read the file DeployREADME.doc on how to install and use the broker.
The project source code is hosted at Bitbucket - K2-Exchange-OOFSettings.