Access to heterogeneous data sources may be obtained by interactively determining transformations for use in mapping at least one source data component from at least one data source to a target data component. Selection of at least one the source data component is detected. A corresponding list of representative data examples is generated for each selected source data component. A resulting list of representative data examples is compiled for the target data component from the lists of representative data examples of the selected source data components, the resulting list of data examples being representative of the target data component. A modification of an example is identified from the resulting list of examples representative of the target data component, the example being modified as a single textual entity. At least one transformation is determined, by inferring from the modified example, to be applied to at least one source data component.