The concept of System of Systems (SoS) has become a key to handle the complexity of large scale systems designed in domains such as aerospace or defense. Virtual prototyping, by providing modeling and execution, increases the success of the SoS. Large scale systems involve heterogeneous modeling and execution formalism. Typical approaches based on types fail in offering the needed dynamicity to answer the virtual prototyping requirements. In order to bridge the existing gap between system models and execution tools, we suggest an approach based on roles and parser combinators. Roles provide a dynamic coupling between modeling and execution allowing independent evolution of modeling and execution. Parser combinators ease the integration of new modeling formalisms. This approach has been validated on a seafloor observatory project and lead to the implementation of a framework in Smalltalk.