1. A method for generating a mapping scheme, the method comprising: reading source data definition that includes information about attributes of a source; reading target data definition that includes information about attributes of a target; receiving commands from a user, wherein said commands establish a mapping between one or more attributes of said source and one or more attributes of>said target; and based on said commands, automatically generating a mapping scheme that represents said mapping, wherein said mapping includes at least one of multiple attributes of said source mapped to a single attribute of said target; and multiple attributes of said target mapped to a single attribute of said source.