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Infodrivers are the primary storage mechanism for dynamic data in BNCS. Each BNCS device instance has a single Infodriver although multiple devices being controlled from the same BNCS workstation can share an infodriver - please refer to the BNCS documentation for a more detailed description.

 

Unlike Databases, Infodrivers only ever have a single owner (or source of truth) on the BNCS network at any point in time.  Any workstation can request a change to an infodriver slot but the owner must accept that change, implement it on the physical device being controlled and then propagate the change to any other interested parties on the network.  On start-up, a workstation must explicitly request the current state of any infodrivers it is interested in and then subscribe to changes.

 

The content of an infodriver slot, or row, is a string although, as with Databases, individual drivers are free to format the contents of the string as they choose.  

 

A driver can initialize its own infodrivers (referred to as Managed Infodrivers) or monitor infodrivers hosted elsewhere (called a monitored or client infodriver)  

 

Unlike previous versions of BNCS, Managed Infodrivers now run internally to the driver rather than as a separate application.  The index range of an internally managed infodriver is significantly larger than the 4096 limit of previous, externally hosted infodrivers.

 

Infodrivers are also key to the operation of Parameters as described in the next chapter.  In this chapter, we will discuss connecting to infodrivers (both managed & monitored) directly and without parametrisation.