I will be doing a more complete post once we have the updated SharePoint Online Nuget package that will allow JS and .NET interaction with the Resource Engagement API (due out late July/ early August), but as I’ve seen a few questions coming in I though it worth an introductory posting. The REST endpoint is now exposing the Engagement stuff – so you could start playing today if REST is your thing.
*** Update 8/5/2016 - Nuget package available - https://www.nuget.org/packages/Microsoft.SharePointOnline.CSOM - 16.1.5521.1200 ***
Here are my requests from Project Professional
And I can see the same in PWA
And if I navigate to the _api/ProjectServer endpoint I can see the engagements there too – using https://<yourtenant>.sharepoint.com/sites/pwa/_api/ProjectServer/Projects('<Project GUID>')/Engagements I see my committed engagement:
and the September one that is still to be accepted.
I can also get at these via the resource by using a Url like https://<yourtenant>.sharepoint.com/sites/pwa/_api/ProjectServer/EnterpriseResources('<Resource GUID>')/Engagements
*** And as Ryan mentioned in the comments "You should access the Engagements off of the project in order to create, modify, submit, or resubmit requests for resources. You should access engagements off of the resource in order to approve or reject them." ***
More later, once the JS and .NET stuff is published via the new SharePoint Online Nuget package towards the end of July 2016 – and it will be here - https://www.nuget.org/packages/Microsoft.SharePointOnline.CSOM/ when it lands.