An article comprising a tangible machine-readable storage medium embodying instructions that when performed by one or more machines result in operations comprising: receiving a request originating at a frontend server for data encapsulated in a plurality of business objects, the plurality of business objects being stored in a business object layer at the backend server, the request originating from a user interface layer and being received by a controller layer; instantiating a controller object in the controller layer at the backend server, the controller object having nodes that are mapped to nodes in the plurality of business objects so that the controller object encapsulates the requested data; and initiating transmission of data response to the request encapsulated by the controller object to the frontend server, wherein the controller object has an extension field (621, 623, 625, 627) corresponding to a visible data field on the user interface, the extension field being mapped to an extension field (621, 623, 625, 627) of a business object node, and wherein a backend service adaptation mapping definition is created from extension fields, the mapping definition containing information that characterizes which extension field in a proxy structure of the controller object is mapped to which extension field in a proxy structure of an underlying business object; rendering at least a portion of the data in a user interface in the user interface layer, wherein data displayed together in the user interface is grouped together into a single controller object, and wherein the extension field (621, 623, 625, 627) is visible on the user interface at the user interface layer. receiving a request originating at a frontend server for data encapsulated in a plurality of business objects, the plurality of business objects being stored in a business object layer at the backend server, the request originating from a user interface layer and being received by a controller layer; instantiating a controller object in the controller layer at the backend server, the controller object having nodes that are mapped to nodes in the plurality of business objects so that the controller object encapsulates the requested data; and initiating transmission of data response to the request encapsulated by the controller object to the frontend server, wherein the controller object has an extension field (621, 623, 625, 627) corresponding to a visible data field on the user interface, the extension field being mapped to an extension field (621, 623, 625, 627) of a business object node, and wherein a backend service adaptation mapping definition is created from extension fields, the mapping definition containing information that characterizes which extension field in a proxy structure of the controller object is mapped to which extension field in a proxy structure of an underlying business object; rendering at least a portion of the data in a user interface in the user interface layer, wherein data displayed together in the user interface is grouped together into a single controller object, and wherein the extension field (621, 623, 625, 627) is visible on the user interface at the user interface layer.