A VISUAL DATA-FLOW ENVIRONMENT FOR MACROMOLECULAR CRYSTALLOGRAPHIC COMPUTING

This article describes the integration of programs from the widely use d CCP4 macromolecular crystallography package into a modern data flow visualization environment (application visualization system [AVS]), wh ich provides a simple graphical user interface, a visual programming p ar adigm, and a variety of 1-, 2-, and 3-D data visualization tools fo r the display of graphical information and the results of crystallogra phic calculations, such as electron density and Patterson maps. The CC P4 suite comprises a number of separate Fortran 77 programs, which com municate via common file formats. Each program is encapsulated into an AVS macro module, and may be linked to others in a data flow network, reflecting the nature of many crystallographic calculations. Named pi pes are used to pass input parameters from a graphical user interface to the program module, and also to intercept line printer output, whic h can be filtered to extract graphical information and significant num erical parameters. These may be passed to downstream modules, permitti ng calculations to be automated if no user interaction is required, or giving the user the opportunity to make selections in an interactive manner.