## 6 SSNs Projects
Most recently due to the evolution of WSNs' field, new paradigms as sensor-cloud and sensor-grid appeared, a large amount of data is collected every minute from different applications, like RFDI, weather, habitat monitoring, building monitors, surveillance, remote sensing data, such as radar, etc.... the generated data needs to be processed, filtered, interpreted, cached,and archived in order to provide a useful infrastructure for users, thus PRESTO is presented to provide the interactivity of the data streaming approach with the energy efficiency of the direct sensor querying. PRESTO design focuses on five main characteristics briefly described, as follows: (1) **Tiered Design**: because the large scale sensor networks of the future are expected to be multiple tiers, with several tens of untethered sensors per tethered sensor proxy and several tens of sensor proxies per application. (2) **Predictive Storage**: PRESTO makes extensive use of predictive techniques that are a natural fit to the correlated behavior of the physical world. Technology trends in storage are exploited to build an architecture that emphasizes archival at remote sensors and extensive modeling and predictive caching at proxies. (3) **Interactive Use**: PRESTO is designed for rapid responses to users posing ad-hoc queries on the distributed sensor data without incurring the energy costs of the data streaming approach or the losses, latency, and reliability concerns of directly querying remote sensors. (4) **Archival Queries**: PRESTO supports archival queries on data that may be deemed to be an interesting _post-facto_. The ability to query historical data is important in many sensor applications to conduct postmortems of unexpected and unusual events to better understand them in the future. (5) **Single Logical View of Data**: PRESTO aims to provide a single logical view of data distributed across many sensor proxies and numerous remote sensors. Such a view can abstract the user from variability's at many levels; unreliable remote sensor network, spatial and temporal consistency issues in sensor data, as well as bandwidth and connectivity issues in the case of wireless proxies. 6. **WebDust**[94]: is a generic and modular application environment for developing applications for WSNs, it gives the application developer the facility to develop a customized environment based on the application requirements, and this will provide a wide range of services for WSNs. WebDust stores the gathered information from WSN in a database to offer extendable statistics and provide users different web-based interfaces to present the gathered information according to the application requirements. The WebDust environment gives motes and devices the ability to automatically register technical characteristics in heterogeneous hierarchical sensor networks. WebDust has many strengths (1) due to the automatic mote registration, it gives the administrator an easy setup and good control for the sensor network. (2) Multiple, heterogeneous WSNs can be treated as a unified VSN. (3) The web-based application interface gives users the ability to access, monitor, query data, etc. in a simultaneous way. 7. **CitySense**[95]: it is a large-scale urban sensor network testbed of more than 100 sensor nodes that are powered by streetlights across the city of Cambridge. Each sensor node is connected to its neighbors via a radio link, and it uses ad hoc routing protocols to communicate with each other using network layer (IP), also each node is directly programmed by the end user, where the project team aimed at allowing multiple users and applications to share the CitySense testbed because this project was designed to facilitate a broad range of research projects in large-scale sensor networks. Thus, this testbed is open to researchers, by using a web-based interface that gives them the availability to collect data, experiment with networking protocols, and reprogram nodes based on the experiment requirements.