This paper describes the architecture and implementation of a constraint-based framework for rapid prototyping of distributed applications such as virtual simulations, collaborations and games. Our framework integrates three components based on (concurrent) constraint programming ideas: (1) Hybrid cc, a (concurrent) constraint modeling language for hybrid systems, (2) Sisl, a (discrete) timed constraint language for describing interactive services with flexible user interfaces and (3) Triveni, a process-algebraic language for concurrent programming. The framework is realized as a collection of tools implemented in Java. The utility of the ideas are illustrated by sketching the implementations of simple distributed applications.