1. A method for a workflow for an ETL (extraction, transformation, loading) process comprising operating a computer to perform steps of: displaying in a first area of a display system a view of a first data transformation from among a plurality of data transformations, the ETL process comprising the plurality of data transformations; displaying in a second area of the display system a view of input data; displaying in a third area of the display system a view of output data generated by performing the first data transformation on the input data; receiving information indicative of a change to the first data transformation to define a modified data transformation; and in response to receiving the user input, displaying in the third area a view of output data generated by performing the modified data transformation on the input data.