Due to the deregulation of the financial industry, bank branches now need to shift to a sales-oriented base, from an operation-oriented base. There are two types of office functions in a branch: front-office operations (i.e., counter work), and back-office operations. The latter functions require many office clerks and large amounts of time. To enable efficient back-office operations, banks are now moving these operations to centralized business operation center. Forms received from customers at branches are scanned with image scanner, and the scanned data are then transferred electronically to the centralized business operation center. There, the back-office functions can be performed more effectively. Branches handle a wide variety of forms, to which the centralized business operation center must correspond. Consequently, the challenge is to reduce the development cost of client applications used in this center. We propose new client application architecture based on a framework extending the Delegation Event Model and a component connection method using an event adapter. In this architecture, client applications can be developed by simply describing the screen configurations and their transitions in XML documents. By utilizing our architecture, we developed client applications for the central business operation center of a new bank branch system. Our experiments demonstrated a reduction in development cost of about 60%.