We consider a challenging class of emerging, highly interactive virtual environments which we call Real-Time Online Interactive Applications (ROIA). Popular examples include multi-player online computer games, e-learning and training applications based on real-time simulations, etc. ROIA combine tough demands on the level of scalability and highly intensive user interactivity with real-time QoS requirements on distributed performance. A major problem in this context is the efficient and economic utilization of server resources for distributed service provision, which is very difficult to achieve due to the variable numbers of users. In this paper, we propose a novel combination of two platforms that address this challenge by utilizing Cloud Computing for ROIA provision: we extend the Real-Time Framework (RTF) by the novel Cloud resource management system RTF-RMS. RTF is a high-level development platform that provides suitable management and scalability mechanisms for ROIA. RTF-RMS is a resource management system on top of RTF that implements workload analysis and distribution techniques. We illustrate how RTF-RMS interacts with RTF and describe how both platforms are used together to scale application servers up and down during runtime to conform to a changing number of users.