—As sensor networks become increasingly popular, heterogeneous sensor networks are being interconnected into federated sensor networks and provide huge volumes of sensor data to large user communities for a variety of applications. Effective metadata management plays a crucial role in processing and properly interpreting raw sensor measurement data, and needs to be performed in a collaborative fashion. Previous data management work has concentrated on metadata and data as two separate entities and has not provided specific support for joint real-time processing of metadata and sensor data. In this paper we propose a framework that allows effective sensor data and metadata management based on real-time metadata creation and join processing over federated sensor networks. The framework is established on three key mechanisms: (i) distributed metadata joins to allow streaming sensor data to be efficiently processed with their associated metadata, regardless of their location in the net...