A data dictionary is provided that specifies the entities and corresponding attributes for the application program interface developers to use. An extensible markup language interface is provided for customers to perform operations on the data. Application program interfaces receive extensible markup language requests and generate extensible markup language response documents that may return data from the database. A set of classes is also provided that correspond to the entities that are defined in the data dictionary. These classes define utility methods for use in retrieving data. The application program interface then appends the returned response object at the depth necessary in order to generate an extensible markup language document.