Report Generation Using a Visual Programming Interface

Command language interfaces are not always the most appropriate tool at the initial stages of report design. A loosely constrained graphical notation can be much more useful. Visual programming techniques introduced on the Xerox Star™, and popularized by the Apple Lisa™ and the Macintosh™, have now made the use of such a graphical notation much more feasible. Also, the direct manipulation techniques described by Schneiderman are now viable because of the wide-spread availability of bit-mapped graphics screens and pointing devices such as the mouse. This paper briefly discusses visual programming concepts, and then describes the implementation of a visual programming interface (VPI) for a 4GL report writer. The basis for the design is an object-action syntax. A set of icons was designed which represent atomic report entities, and a graphic editor built to manipulate these entities into a report structure. Attribute sheets associated with each of the report entities allow definition of the report entities to the data dictionary. A menu bar controls menus of all possible actions to be performed on the objects. A facility to switch easily between the graphical and textual representation of the report is provided, with direct manipulation editing available in both representations. Modifications made in one representation are automatically reflected in the other. The combination of the VPI with a 4GL makes the design and modification of reports remarkably straightforward, and suitable both for end users and application programmers.