Today?s business applications are typically built on top of middleware platforms such as J2EE and use transactions that have evolved into long running activities able to adapt to different circumstances. Specifications, such as the J2EE Activity Service, have arised for applications requiring that support. These applications also demand high availability to prevent financial losses and/or service level agreements (SLAs) violations due to service unavailability or crashes. Replication is a means to attain high availability but current middleware does not provide highly available transactions. In the advent of crashes, running transactions abort and the application is forced to re-execute them, what results in a loss of availability and transparency. Most approaches using J2EE consider the replication of either the application server or the database. This results in poor availability when the non-replicated tier crashes. This paper presents a novel J2EE replication support for both, application server and database layers providing highly available transactions and long running activities. Failure masking is transparent to client applications. A prototype has been implemented and evaluated.