1. A method of generating application code and an external interface for a service class in an enterprise resource planning system, the method comprising: receiving a definition of a service class from a user via a user interface tool, the definition specifying a query on which the service class is to be based and operations to be enabled for the service class; automatically generating application code for the service class based on the received definition, the application code enabling the service class to be consumed by an internal endpoint of the enterprise resource planning system, the application code customizable by the user by adding additional operations; and automatically generating an external interface for the service class based on the generated application code and any customization by the user, the external interface enabling the service class to be consumed by an external endpoint of the enterprise resource planning system without requiring the external endpoint to have knowledge of the application code, so that internal and external endpoints may request access to services of the enterprise resource planning system, and that the enterprise resource planning system, upon receiving from an endpoint a request to access a service, may dispatch the request to an appropriate service class.