This paper presents a complete system model for scheduling and dispatching CORBA service requests that have hard as well as soft real-time timing requirements in a distributed environment. The model provides the methodology for expressing and enforcing time-based QoS constraints for real-time CORBA service requests. Therefore, the presented model complements the state of the art in real-time scheduling in CORBA-based systems. The model is based on using the distributed time-based parametric scheduling method. This method is used to verify the feasibility of a distributed periodic hard real-time task set and to generate dispatching calendars that dynamically adapt to run-time environment.