Business Web applications are complex data- and operation-intensive Web applications intended to support business processes. In this kind of application, the user executes sets of activities organized into transactions (also generally called workflows) in order to accomplish one of his/her tasks or fulfill one of his/her goals. The way these transactions are structured, the properties associated with their component activities and the way each activity is implemented by the Web application are a consequence of the transaction design as well as the business rules implied by the business process. The Ubiquitous Web Applications (UWA) design framework explicitly includes a design activity and a related meta-model, called the Transaction Design Model, specifically focused on the conceptual design of Web application transactions (Web Transactions for short). This paper describes preliminary steps towards a revised and extended version of the UWA Transaction Design Model that emphasizes a user-centered approach, is easier to adopt and manages the information, navigation and operation aspects involved in a Web Transaction in a comprehensive and integrated way.