ts the abstraction of e-Transactions in three-tier architectures. Three-tier architectures are typically Internetoriented architectures, where the end-user interacts with frontend clients (e.g., browsers) that invoke middle-tier application servers (e.g., web servers) to access back-end databases. We t the e-Transaction abstraction using an asynchronous replication scheme that preserves the three-tier nature of the architecture and introduces a very acceptable overhead with respect to unreliable solutions. 1 Swiss Federal Institute of Technology, Lausanne, CH 1015 ∗ This paper is an extended and revised version of a paper, with the same title, that appears in the proceedings of the IEEE international Conference on Dependable Systems and Networks, 2000 (DSN’2000). © Copyright Hewlett-Packard Company 2000 Internal Accession Date Only