Sensor networks are used in a great deal of realms such as home monitoring, environmental monitoring (e.g., weather forecasting), health monitoring (e.g., pacemaker, brain waves), vehicular networks, etc. The authors are surrounding by sensor networks such as healthcare, home or environmental monitoring, weather forecasting, etc. All sensor-based applications proposed are domain-specific. They aim to link these heterogeneous sensor networks to propose promising applications. Existing applications add semantics to the sensor networks, more specifically, to the context, rather than to the sensed data. They propose an architecture to merge heterogeneous sensor networks, convert measurements into semantic data and reason on them.