1. A system for providing an information service based on heterogeneous sensor networks, comprising: a sensor node constructing a sensor network to sense environment information; a sensor network data transmitter for collecting sensed data sensed by the sensor in real-time and transmitting the collected sensed data in a message form; and a Ubiquitous Sensor Network (USN) middleware for extracting object and environment information by cleaning, classifying and integrating the message received from the sensor network data transmitter, generating conditional events, context aware information, and knowledge contents from the extracted object and environment information, and providing the information service to an application program, the application program providing a user with information related to environment where the sensor network is installed.