Link to [Original Issue](https://github.com/d-velop/dvelop-sdk-node/issues/156). As a d.velop App-Builder it would be very helpful to have an example implementation of the App-Session Authentication Process. This is documented [here](https://developer.d-velop.de/documentation/idpapi/en#IdentityproviderApp-Inter-appcommunicationwithappsessions) and a basic tutorial can be found [here](https://developer.d-velop.de/dev/en/tutorials/abrechnung-via-billing-app).