The REACTION platform consisting of Health Monitoring Server and Home Gateways, provides seamless integration of wearable and off-the-shelf medical devices, as well as environmental sensors and actuators. The REACTION platform thus creates a solution for multi-parametric monitoring and contextualisation of patient health status. The devices communicate through Web Services, which is the main procedure for communicating throughout the REACTION architecture. Loosely coupled devices are presented as UPnP devices and a Data Management subset transforms data into information. It performs data manipulation and conditioning, perform, simple data analysis, queries, contextualisation and fusion of data to a Service Layer or to external devices or repositories.