In this paper we introduce a multi-level transaction model that provides the necessary independence for the participating resource managers, e.g., local database and workflow servers of organisations, engaging in business transactions composed of interacting web-services. We also present taxonomy of e-business transactions features such as unconventional atomicity criteria, the need for support for business conversations and the need for distinguishing between three basic elements within a business transaction. In addition, we argue that an extensible framework such as the Business Transaction Protocol (BTP) proposed by OASIS is necessary for building robust and extendible e-business applications.