Distributed applications require specific middleware support for semantics and run-time constraints for a wide range of hardware or software configurations. However, their full specifications and existing implementations show they share functional notions and run-time mechanisms. Thus, distribution infrastructures could be prototyped from a given set of middleware components. Generic middleware proposes patterns to describe distribution models; configurable middleware constructs to abide to run-time constraints. We have introduced the schizophrenic middleware concept as a comprehensive solution to rapidly implement different distribution models. PolyORB, our implementation of a schizophrenic middleware, supports CORBA, SOAP, the Ada 95 Distributed System Annex and Message Oriented Middleware distribution models. In this paper, we describe existing generic and configurable middleware; we introduce PolyORB?s key concepts and design; then we compare our platform design to existing generic and configurable middleware, and discuss their respective use to prototype specific distribution models.