The present invention refers to systems and methods for electronic data interchange messaging, i.e. for the interchange of electronic messages comprising and transferring data provided in a predefined, preferably standardized structure or form in such a way that said data may be identified and used as data element values or strings in further processing functions by the receiving system or application. According to the invention, a process to be executed in a computer system and comprising electronic data interchange is defined in relation to a corresponding data defining, comprising a set of data elements for electronic data to be successively interchanged or processed in each execution of said process, wherein said process is arranged to automatically write data included in a received electronic data interchange message into, and read data for electronic data interchange message sending from, predefined data elements of a data instance of the data definition during the execution of said process.