Abstract
Abstract. World-wide sensor web generates tremendous amount of sensor data stream allowing people to observe events that were previously unobservable. Sensor web has been wildly applied in many monitoring systems; some of them are extremely time-sensitive, e.g., disaster management systems. However, with the growing amount of sensor data, the traditional request/response communication model becomes inefficient as it is based on point-to-point pulling interactions between users and data providers. In order to address this issue, publish/subscribe communication model has been proposed and applied in many applications, e.g., web blogging. The publish/subscribe model utilizes an intermediary broker on matching predefined queries with the data pushed to the broker. However, we argue that the publish/subscribe model is hard to be directly applied to sensor web due to the fact that most sensor web services are based on pulling interaction model only. For instance, more and more sensor data providers are publishing their sensor data with the Open Geospatial Consortium (OGC) Sensor Observation Service (SOS) standards, and the OGC SOS services are based on the request/response model. Therefore, in order to address this issue, we propose a hybrid pull-push system to retrieve sensor web data in a timely manner. The preliminary experimental results indicate that the proposed system is able to fetch near real time sensor streams from pull-based sensor web services.
Highlights
1.1 BackgroundThe World-Wide Sensor Web (Liang et al, 2005) is generating tremendous volumes of real-time sensor data streams ranging from video camera networks monitoring real-time traffic to matchbox-sized wireless sensor networks embedded in the environment to monitor habitats
We argue that a major reason of this slow adoption is that the most current sensor web services are currently based on pulling model only
This paper focuses on the input adaptor module in a publish/subscribe system to retrieve sensor data from pull-based sensor web services in a timely manner
Summary
The World-Wide Sensor Web (Liang et al, 2005) is generating tremendous volumes of real-time sensor data streams ranging from video camera networks monitoring real-time traffic to matchbox-sized wireless sensor networks embedded in the environment to monitor habitats. Open Geospatial Consortium (OGC) Sensor Observation Service (SOS) (OGC 2007), as one of the most popular open sensor web standards, defines a standard protocol for users to retrieve sensor metadata and observations through Internet This issue impedes users from getting real-time notifications about events happening on sensor web. In order to address this issue and achieve the goal of timely notification, this paper proposes a hybrid pull-push system for near real-time sensor data notification. This system contains three major components, namely (1) query aggregator, (2) adaptive feeder, and (3) sensor data cache.
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