Hi Marcel,
I agree with Sandeep and followed the similar design to upload master data to Ariba using ITK. In our solution, we have used SAP PI as middleware and scheduled the ITK jobs on PI server. SAP ECC generates the master data csv files in AL11 folder from where we move them to PI server ITK folder. As soon as the ITK job runs it picks up the csv and load the master data to Ariba.
Let me know if you need more details.
Thanks
Varun Goel