Connectivity Framework
3 : Connectivity Reference Architecture
K ) vs . the original N *( N-1 )/ 2 shown in Figure 3-1 . Assuming K << N , the number of gateways goes from O ( N ²) to O ( N ), which is much more tractable .
Each additional core standard creates increasing complexity and interoperability challenges with the square of the number of core standards . A few ( small K ) core connectivity standards should suffice to cover the needs of IIoT systems across the functional domains and industries to attain the goal of horizontal interoperability .
3.4 CORE STANDARDS CRITERIA
A connectivity core standard should align with the priorities on the requirements , engineering tradeoffs and ecosystems in its functional domain . It should not get in the way of providing seamless interoperability between domain-specific endpoints connected to it via gateways . This means meeting not only the functional requirements , but also the non-functional requirements of reliability , performance , scalability , availability , security and safety . Below , we define the criteria for qualifying as a connectivity core standard .
A connectivity core standard shall :
• provide syntactic interoperability ,
• be an open standard with strong independent , international governance , and with support for certifying or validating or testing interoperability of implementations ,
• be horizontal and neutral in its applicability across industries ,
• be stable and deployed across multiple vertical industries ,
• have standards-defined Core Gateways to all other connectivity core standards .
A connectivity core standard shall provide syntactic interoperability ( see section 2.2 ). It is not simply sending opaque blobs . Applications not only get the data , but they can also discover the data types to unambiguously parse and manipulate it as structured data . So , an application will , for instance , know that the data it received is a structure with three floating-point number fields and a string field . The connectivity stack ( see section 2.1 ) does not provide semantics — the interpretation of the fields , such as the units , ranges , and context is important for IIoT systems , but outside the scope of connectivity , and covered by the Distributed Data Interoperability and Management layer in the Industrial Internet Reference Architecture .
A core connectivity standard shall be an open standard managed by a recognized standards development organization ( SDO ). The SDO should provide independent , international governance . There should be support for validating or certifying or testing interoperability of implementations adhering to a specification from the SDO .
A core connectivity standard shall be stable and deployed in systems across multiple industries . It should not qualify until it has been fielded and has operational proof points in fielded systems . Connectivity standards that are not proven deployed across multiple industries or in fielded systems can be considered a common connectivity standard in one or more specific industries . We should strike a balance between leading the industry and lowering risk . We set that balance at the point of deployed applications across industries .
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