1. A mixed language programming method for making a function or procedure written in a native language accessible to a Java application, said method comprising the steps of: receiving a native interface description that describes said function or procedure; parsing said native interface description; and processing said parsed native interface description to generate data conversion code stubs containing Java Native Interface functions required to implement said function or procedure and a Java class definition for said function or procedure, wherein said function or procedure, said data conversion code stubs and said Java class communicate directly by means of the Java Native Interface.