Abstract: A query system (1600) is formed by a wizard (1605) operating to form a data server (1610) arranged to serve data from a data source (1615) to a client application (1630), each of the wizard, the client application, the data server and the data source being linked by a communications network (1650). The data source has native data types and data arranged in a data structure. The wizard operates to firstly identify the data source over the network. The wizard further provides an application program for traversing and examining at least one of the data structure and data of the identified data source. The application program is operable to generate a representative schema (1614) comprising mapping data for converting the native data types to predetermined data types of a common data model.