Connectivity Framework
4: Connectivity Framework Layer
Data-centric connectivity frameworks fit well with multi-party development, simplify the integration effort and reduce the overall effort and time to debug and integrate components into systems. Because the interfaces to the data are explicit in the design, a data-centric approach results in an open architecture. Components become independent of the data, thereby simplifying the system development and evolution and increasing reusability. Data-centric systems also scale well to large systems. However, it can be challenging for IIoT systems integrators to require their vendors use a common data-centric abstraction.
For IIoT systems, open architecture is highly desirable, since it allows multiple data sources to be combined together to generate new value, insights and applications.
Many system designers choose between device-centric or data-centric core connectivity standards based on the relative need of integrating similar brands of devices vs. reducing complexity and easing development of the software. Regardless of the chosen method, connectivity frameworks should allow for both approaches.
4.2.1.3 EXPLICIT VS. IMPLICIT GOVERNANCE
Connectivity framework governance( see section 4.1.13) may be explicit or implicit or a mix. When governance is explicit, configuration elements can be controlled independently of the applications; they can be shared and managed through a common repository. When governance is implicit, configuration elements are embedded within the application code across the various system components.
Explicit governance allows data architecture evolution and upgrades in a controlled fashion, independently of the application code. This is beneficial for large teams working on safety-critical systems where the development needs to be carefully managed, while enabling multiple subteams to work independently.
Implicit governance works best for organic evolution and requires that the data architecture be discoverable via dynamic APIs.
4.2.2 DATA CONSIDERATIONS
4.2.2.1 CONTENT-BASED SELECTION
IIoT systems involve movement of large volumes of data. Components are only interested in a specific subset of the data at a given time, although that interest set may change. Given the data interest set across the components, connectivity frameworks can optimize the data distribution, resulting in lower overall system resource footprint, and so lower system cost.
For IIoT systems, the ability to specify a content-based data subset of interest and automatically optimize the data flows is highly desirable.
4.2.2.2 TIME-BASED SELECTION
IIoT systems typically involve distribution of high frequency data. A component may produce data faster than some consuming components desire or are able to handle. In this situation, time-
IIC: PUB: G5: V1.0: PB: 20170228- 34-