IIC Journal of Innovation | Page 41

A Horizontal Taxonomy for the Industrial IoT In this framework, architectural approaches and the technologies that implement them can be considered to “occupy” some region in this N-dimensional space. For instance, a data-centric technology like the Object Management Group (OMG) Data Distribution Service (DDS)2 provides peer-to-peer, fully-redundant connectivity with content filtering. Thus, it would occupy a space that satisfies many Reliable, Real-Time applications with significant numbers of Data Items, the first three challenge dimensions above. The Message Queuing Telemetry Transport (MQTT) protocol, on the other hand, is more suited to the data collection focus challenge. Thus, these technologies occupy different regions of the solution space. Figure 11 represents this concept in three dimensions. Figure 11: N-Dimensional Requirement Space Architectural approaches and their implementing technologies satisfy some range of each of the dimensions above, and thus occupy a region in an N-dimensional “requirement space”. The value of a taxonomy is to help designers decompose their problem into relevant dimensions so they can then select an appropriate approach. Thus, the application can be placed in the space and the architectural approaches represented as regions. This reduces the problem of selecting an architecture to one of mapping the application point to appropriate architectural regions. Of course, this may not be a unique map; the regions overlap. In this case, the process indicates options. The tradeoff is then to find something that fits the key requirements while not imposing too much cost in some other dimension. Thinking of the system as an N-dimensional mapping of requirements to architecture offers important clarity and process. It greatly simplifies the search. 5. TAXONOMY BENEFITS Defining an IIoT taxonomy will not be trivial. The IIoT encompasses many industries and use cases. It encompasses much more diversity than specialized industry, enterprise IT, or even “consumer” IoT applications. Technologies also evolve quickly, so the scene is constantly shifting. This work just scratches the surface. However, the benefit of developing a taxonomical understanding of the IIoT is enormous. Resolving these issues will help system architects choose protocols, network topologies, and compute capabilities. Today, we see designers struggling with issues like server location or configuration, when the right design may not even require servers. Overloaded terms like “real time” and “thing” cause massive confusion between technologies despite the fact that they have no practical use-case overlap. The industry needs a better framework to discuss architectural fit. 2 www.omg.org/dds - 40 - December 2015