A metadata driven software development system provides various functionalities related to an entity of an application in the metadata format. Specifically, the system provides a set of base classes related to the entity and a set of methods and application programming interfaces for various operations to be performed on the entities in the metadata format. Defining such functionalities in the metadata format allows the system to dynamically generate XML messages matching any customized schema for that entity. Because such functionality is metadata driven, this system can be used with customized versions of the application without requiring any additional code or recompilation.