Artificial Versus Natural Worlds
Resilience is the capability of a system to resist threats, evolutionary changes and internal weaknesses; to maintain essential services, and learn to adapt and improve. In other words, artificial or man-made systems will be able to exhibit a certain level of intelligence. In the natural world, a hierarchical order of species is used for model and description, and we will make an analogy in the proposed artificial system. Table 1 combines intelligence level with reaction latency and a typical volume of data to be handled – as pseudo requirements for our IoT ecosystem.
Engineering a highly complex, constantly evolving and adapting system implies a very careful tradeoff among cost, performances and resilience. This trio obeys an old engineering chestnut: pick any two and forget the third. So, if you want a performant and resilient system, forget the cost – it will be very expensive.
Layered, Hierarchical and Resilient Architectures
In the previous century, one of the forefathers of Artificial Intelligence and Complex Systems, Herbert Simon , described the hierarchical structure of complex systems as the best model to exhibit superior performances. Simon viewed these structures, roughly speaking, as a set of embedded control loops able to operate autonomously while in synch with inside and outside loops. Along these lines, we suggested the following conceptual IoT architecture, consisting of three engineering layers which we will describe briefly.
On top, the Cloud level will exhibit intelligence comparable to human, that is to exhibit resourcefulness. The distinguishing characteristic of a resourceful system is that it is able to adapt its behavior automatically in a changing environment. For example, in a computer chess playing game, if the program loses its queen it is able to formulate a new plan for winning the game. Generating code or procedures based on AI techniques to maintain service when losing a resource will take a certain amount of time which has an impact on latency. Resourcefulness also implies the ability to deliver any scale, speed or capacity of resources.
The middle layer, called opportunistically Intelligent Edge, is about redundant and resilient communication ensuring permanent connectivity even in a catastrophic situation: reduced capacity and capability, but available. The mechanisms used in this layer are the typical network and system detect, failover, recover and repair techniques for network and software high availability.
The bottom layer, consists of smart Edge devices embodying an insect-style of intelligence which implies a high level of autonomy and redundancy. The mechanisms for resilience at this level are pre-established rules that encode the reactions to changing environmental conditions with safety as the primary concern. Very little processing can be done in order to satisfy the very low latency requirements, similar to the way we instinctively withdraw our hands when touching a very hot surface without thinking about it.
When taken all together, engineering a resilient IoT system will treat, provide and ensure resilience in all three layers while providing orchestrated, coordinated and coherent behavior of the system as a whole. Early research in Artificial Intelligence has explored and developed models of such systems. It seems the time has come that contemporary technologies may enable construction of such superior and resilient systems. And if we recall the saying of the brilliant Leonard da Vinci , we still have a lot to learn from Mother Nature. Therefore, we will be facing interesting times in IoT developments.
 Jeffrey Voas – NIST, Network of ‘Things’, https://www.nist.gov/sites/default/files/documents/itl/antd/Jeff_Voas.pdf
 Herbert Simon, The Sciences of the Artificial, The MIT Press, September 1969
 Leonardo Da Vinci, ‘Trattato della pittura’ – Those who took other inspiration than from Nature, master of masters, were laboring in vain. [Leonardo da Vinci – 1500] – Quegli che pigliavano per altore altro che la natura maestra de’ maestri s’affaticavano invano. LEONARDO DA VINCI, Trattato della pittura, 1500 c.