In this paper, we propose a novel framework, called CATER, for the automated layout of web application user interfaces. This framework is a constraint-based solution, which uses a decision-table to solve the issue of field-to-widget assignment between database table and transactional page and then produces the later automatically. It caches the code skeleton of autogenerated transactional pages and gathers selection frequency of data items from temporary log files respectively to improve the computing performance and optimize the layout of transactional pages. Furthermore, this framework takes into account the UI layout, data validation, persistent store, navigation (flow control), and maintenance completely. Therefore, it can be used as a general solution for transactional web applications.