Software architecture styles for developing multiuser applications are usually defined at a conceptual level, abstracting such low-level issues of distributed implementation as code replication, caching strategies and concurrency control policies. Ultimately, such conceptual architectures must be cast into code. The iterative design inherent in interactive systems implies that significant evolution will take place at the conceptual level. Equally, however, evolution occurs at the implementation level in order to tune performance. This paper introduces Dragonfly, a software architecture style that maintains a tight, bidirectional link between conceptual and implementation software architectures, allowing evolution to be performed at either level. Dragonfly has been implemented in the Java-based TeleComputing Developer (TCD) toolkit.