Towards a uniform software interface to heterogeneous hardware

Traditional sensor network infrastructures rely heavily on middleware software to interface with various instruments. In the current state, plugin-based middleware software does not offer the flexibility required to achieve ldquoplug & playrdquo, where users can simply connect new sensors and instruments and expect them to work straight away. In this paper, we introduce a low-level software layer which encapsulates all hardware-related functionalities and aims at removing hardware-dependent code from middleware software and facilitating interactions with sensors and instruments. The Sensor Abstraction Layer (SAL) implements hardware detection, configuration, access and control functions and enforces a clear separation of responsibilities with respect to hardware interactions. Using SAL, middleware software can be made device- and technology-independent. Hardware management functions are only implemented in SAL, which avoids code duplication and promotes code re-usability across middleware technologies. SAL solves many of the issues current middleware products have with respect to hardware detection and configuration, as it automates most of these tasks, making new instruments available for immediate use as soon as they are connected.