A system and method for generating application code and an external interface for a service class, in an enterprise resource planning (ERP) system is provided. The system receives a definition of a service class from a user via a user interface tool. The definition of the service class specifies a query for the service class and operations that are to be enabled for the service class. The system automatically generates application code for the service class, which enables the service class to be used by an internal endpoint of the ERP system. The application code is customizable by the user; the user may add additional operations to the service class. In addition, the system automatically generates an external interface for the service class, which enables the service class to be used by an external endpoint of the ERP system without needing knowledge of the application code.