1. In a computing system comprising an extensible serialization engine that is capable of serializing and deserializing data objects of various types, a method of transforming an initial object of an initial type to a final object of a final type, wherein the method allows for runtime operation of the serialization engine to be altered by one or more extension routines, without having to replace a monolithic implementation of the serialization engine, the method comprising acts of: receiving an initial object of an initial type for runtime processing by the serialization engine; receiving type information for the initial type of the initial object; based on the type information, generating an intermediate representation of the initial object that is suitable for runtime modification; calling one or more custom extension routines to change the intermediate representation of the initial object to a modified intermediate representation of the initial object, thereby altering the runtime operation of the serialization engine; and from the modified intermediate representation of the initial object, generating a final object of a final type.