This paper presents an architecture for web-based interaction and steering of parallel/distributed scientific applications. The architecture is composed of detachable thin-clients at the front-end, a network of web servers in the middle, and a control network of sensors, actuators and interaction agents at the back-end. The interaction servers enable clients to connect to, and collaboratively interact with registered applications using a conventional browser. The application control network enables sensors and actuators to be encapsulated within, and directly deployed with the computational objects. Interaction agents resident at each computational node register the interaction objects and export their interaction interfaces. An application interaction gateway manages the overall interaction through the control network of interaction agents and objects. It uses Java proxy objects that mirror computational objects to enable them to be directly accessed by the interaction web-server. The...