Connectivity Framework
4 : Connectivity Framework Layer
For IIoT systems , a connectivity framework should effectively handle an increasing number of data objects as more memory resources are added , and should support data objects of varying sizes .
4.2.4.2 APPS
IIoT systems comprise independently developed applications , each with evolving interfaces and data formats that should continue to interoperate with older versions of that interface . Forcing all apps to coordinate their update simultaneously to a new interface and data format version is unrealistic ; there needs to be version negotiation between components . Interacting teams need tools , processes and eventually architectural support to solve the system-integration problem .
Data-centric connectivity frameworks allow applications to control data-oriented interfaces directly . Applications interact with shared data objects described by explicitly defined data types . Differences in data-oriented interfaces between apps can be automatically detected and adapted to match a participant ’ s expectations , so as to decouple application interface dependencies and allow large projects to evolve interfaces and make parallel progress on multiple fronts .
For IIoT systems , a connectivity framework should support component interface evolution so that new capabilities can be added over time , without impacting the already existing components .
4.2.5 AVAILABILITY CONSIDERATIONS
4.2.5.1 REDUNDANCY
Failure of IIoT systems during operation can have fatal consequences . The system-relevant time period of continuous operation is dependent on the context of the system . For a power plant , the relevant time period could span years . For a medical imaging machine , the relevant time period could be only a few seconds .
But hosts and networks do fail , so redundant infrastructure ( duplicate or triplicate or more ) and failover mechanisms should be put in place . They rely on the connectivity infrastructure to communicate fault conditions and effect the appropriate state changes . To provide continuous system availability , a connectivity framework should support redundant endpoints and networks , and remove duplicate data transparently when the same update is received over multiple paths .
For IIoT systems , a connectivity framework should support continuous availability over a systemrelevant time period .
4.2.5.2 RECOVERY
An IIoT connectivity framework should be continuously available . It should not have single points of failure , and it should provide mechanisms for timely detection of system component failures . There should be mechanisms for component state durability and for state recovery and failover .
For IIoT systems , a connectivity framework should provide mechanisms for data durability and state recovery from fault conditions .
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