This paper presents a new approach for the development of data-intensive web applications that depend on sophisticated application logic. E-Commerce web sites, on-line auction systems and large enterprise web portals fall into this category as they require comprehensive data access, data processing and data manipulation capabilities. However, existing methodologies mainly concentrate on modeling content, navigation and presentation aspects of read-only web sites. In our opinion these models are not sufficient to express complex operations that access or modify web application content. Therefore, we propose an additional Operation Model defining the application logic of a web application. We show that based on this model a significant part of a web application’s Operation Layer can be generated, still allowing the manual implementation of arbitrary additional functionality. We evaluate our approach and present experimental results based on a large example application for the area of innovation management.