With the widespread adoption of the Internet of Things (IoT), billions of devices are now connected to the Internet and can reach computing facilities along the Cloud-IoT continuum to process the data they produce. This has led to a dramatic increase in the amount of deployed IoT-based applications as well as the data they need to crunch. Those applications often have Quality of Service (QoS) requirements to be met by determining suitable placements for all services they are made of and all data they manage, as well as software-defined routings across the IoT and all different application components. In this context, we aim at supporting the QoS- and data-aware placement as well as management of multi-service applications onto Cloud-IoT resources. We describe our main objectives and discuss some preliminary results of our research.