# Middleware for Plug and Play Integration of Heterogeneous Sensor Resources into the Sensor Web
## 1 Introduction
This conversion can either be achieved directly on the platform or by an intermediate process on a land station server in the case of resource-constrained platforms. Figure 2 depicts a non-standardized scenario where different sensors are deployed using different observation platforms. As the number of platforms and sensors deployed within a collaborative environment grows, the number of custom components increases, as well as the infrastructure maintenance costs. Therefore, improving the interoperability among the infrastructure's components should be a matter of great concern. Interoperability in this sense can be defined as the ability of two systems to exchange information and to interpret the information that has been exchanged [6]. The ultimate goal of interoperability in a collaborative research environment should be to enable the plug and play integration of sensor resources into observation platforms and data infrastructures, reducing the human intervention to a minimum. This goal implies two different levels of interoperability: operational and data management. From the operational interoperability point of view, a sensor should be automatically detected, configured and its data gathered by the observation platform's acquisition process, as soon as it is deployed into an observation platform. From the data management side, the data retrieved from the sensor should be encoded in a standard format, compatible with the data infrastructure. Sensor metadata plays a key role in the acquisition. If managed properly it will enhance not only the interoperability of the sensor, but also its data traceability and ease further data quality procedures, allowing to pinpoint for example sensor malfunctions [7]. Therefore, metadata should be added alongside sensor data, providing contextual information [8]. Within this work, a standardized, plug and play acquisition chain capable of bridging sensor resources to Sensor Web services is envisioned, implemented and evaluated. Instead of using a specific driver for each sensor-platform combination, the use of a generic driver component configurable through OGC standards is proposed. In order to abstract the peculiarities of each sensor, this approach makes use of a metadata file with a machine-understandable unambiguous sensor description, encoded in a standard way. Afterwards, the generic driver should be able to access such a sensor description file and configure itself accordingly, being able to operate a sensor without any a priori knowledge  
Figure 2: Collaborative research scenario using specific drivers and data converters for each sensor-platform combination, in this case an underwater glider, a buoy and a cabled underwater observatory. of the device nor the observation platform where it is hosted. The gathered sensor data should be encoded in standardized SWE formats, ensuring the plug and play integration of sensors into SWE services. This generic component should also have its own auto-description methods, in order to make their role understandable to both humans and machines. The envisioned architecture is presented in Figure 3.