A system and method for providing composite applications for software-based systems that uses a built-in application model having at least one general purpose object type, and providing dynamic late-binding of object implementations through an object typing system decoupled from pre-run time program code, using persistently stored objects. The application model may require that program objects in a conformant application be instances of a predefined active object type, or optionally instances of a predefined reactive object type. The application model enables integration of applications into composite applications, and further integration of composite applications into subsequently defined systems. The run-time object typing system for persistently stored objects is independent of the class typing system that is defined at compile-time or link-time, and enables convenient and practical modifications during development, deployment and maintenance of composite applications.