is it possible to have this exported from dll: ///export.h/// #include <boost/serialization/serialization.hpp> class session_record { virtual void print_on(std::ostream& os) const = 0; friend std::ostream & operator<<(std::ostream& os, const session_record& sr){ sr.print_on(os); return os; } public: friend class boost::serialization::access; virtual ~session_record(); template<class Archive> void serialize(Archive & ar, const unsigned int file_version){} operator session_record *(); }; void serialize(session_record* derived, const char* file_name); session_record* deserialize(const char* file_name); ///end of export.h/// and then in an application (linked to the dll that exports all from export.h) I create derived classes from session_record and serialize or deserialize them to/from files using the two exported free functions. I followed exactly steps in "Runtime Casting" of the manual, but it doesn't work. So... is it really runtime if it doesn't work this way - it only works if all the derived classes are known & registered at the time of compilation of the two functions. All that worked well if everything from export.h was linked statically, but not dynamically Am I doing something wrong with all that stuff?? thanks