The complexity of data-intensive business processes is typically reflected in the user interfaces of the information systems supporting them. To facilitate ease of use despite the visual and semantic complexity of dialog forms, users should be guided in ways such as highlighting and describing invalid input, showing/hiding or enabling/disabling particular UI widgets. Manual implementation of the rules governing these user interface responses typically requires considerable effort, as they involve business and presentation concerns, and are often dependent on each other. In addition, users expect the interface to respond immediately to any input, which can be especially challenging in web applications. In this paper, we formalize the aspects that must be considered in formulating input evaluation rules, and present a run-time framework that encapsulates the necessary logic, enabling domain experts to specify the business rules instead of requiring developers to implement them.

Development and maintenance of complex web interfaces containing hundreds of input fields typically causes huge development effort. Changing the layout or adding input fields to complex user interfaces are especially tedious tasks are, because these changes affect the alignment of many other interface elements. To reduce this effort, we developed a ruler guide-based approach that combines the efficiency of automatic generation of complex user interfaces from an XML-based specification with the flexibility of a manually layouted user interface. First experiences with a proof-of-concept implementation show that the effort needed for development and maintenance can be significantly reduced.