Looking into the possibilities that come with the WAB I can't see the possibility to refer to one of my own services. Looks like people that have their data at AGOL are fine, but I can't upload certain data to AGOL since I am simple not allowed to give them out of house.
Hence, how is it possible to refer to web services delivered by our own ArcGIS Server?
I found this posting here (Do you have to use AGOL to use WAB? ) that might offer this, but the comments to the initial posting leave me a bit in doubt. Also, it is not satisfying to go via a hack to create standard functionality.