Scenario: In a home or office environment, luminosity variations measured by a light detector drive the operation of an electronically controlled shutter. This scenario can be easily transposed to other domains, e.g., in an industrial automation setting, an optical parts-detector driving a conveyor-belt motor.
Simplistic as it is, this example allows to clearly illustrate the evolution that the SIRENA approach is intended to bring about.
Without SIRENA: Sensors and actuators are linked by dedicated point-to-point connections. An intelligent programmable device is required to run a more or less complex automation program, which needs to be specifically written by a programmer using a special-purpose programming language. Such a device is generically termed a "programmable logic controller". Typically, the automation program is downloaded to this device from a computer through a separate network connection.
With SIRENA: Sensors and actuators are connected over a common network infrastructure (e.g., Ethernet) and communicate directly using IP-based network protocols. Connections are "plug and play", owing to automatic device and service discovery mechanisms. The devices incorporate their own intelligence, making them self-contained and obviating the need of a higher-order control device. What's more, no automation program is needed anymore, as the devices expose their capabilities in the form of high-level services (e.g., "raise shutter, level=0.75"). The use of common networking and service infrastructure grants interoperability between devices belonging to different domains, thus paving the way for new, service-oriented applications.