A number of items of data from a data source (12) can be processed and supplied to a data destination (16, 17). The data can include image data, text data, numeric data or other types of data, or a combination of types of data. The processing of the data is controlled by a project definition (14, 71, 101) which includes a plurality of modules selected from a variety of available modules (Tables 1-4). The modules include input and output ports which are interrelated by binding information. One of the existing modules provides the capability for execution of a specified command in an independent and separate application program. Further, custom modules can be readily prepared, in order to supplement the default set of available modules.