As part of the Carbon2Chem (R) joint research project, mathematical models are involved to simulate operating scenarios for cross-industrial networks. An optimal model-based system integration approach requires a scalable co-simulation framework that enables the distributed development of constituent subsystems. By using a classic waveform relaxation algorithm, model suppliers and integrators can exchange co-simulation units without having to disclose sensitive information and intellectual property. Here, the underlying IT architecture and the basic principles of the introduced "model as a service" approach are described.