An IoT architecture as we have eluded to will span many technologies. As an architect, one needs to understand the impact choosing a certain design aspect will have on scalability and other parts of the system. The complexities and relationships of the IoT because significantly more complex than traditional technologies because of the scale but also due to the disparate types of architecture. There is a bewildering number of design choices. For example, as of this writing, there are over 700 IoT service providers alone offering cloud-based storage, SaaS components, IoT management systems, IoT security systems, and every form of data analytics one can imagine. Add to that the number of different PAN, LAN, and WAN protocols that are constantly changing and varying by region. Choosing the wrong PAN protocol could lead to poor communications and significantly low signal quality that can only be resolved by adding more nodes to complete a mesh. The architect needs to consider interference effects in the LAN and WAN—how will the data get off the edge and on the internet? The architect needs to consider resiliency and how costly the loss of data is. Should resiliency be managed within the lower layers of the stack, or in the protocol itself? The architect must also make choices of internet protocols such as MQTT versus CoAP and AMQP, and how that will work if he or she decides to migrate to another cloud vendor. Choices also need consideration with regards to where processing should reside. This opens up the notion of fog computing to process data close to its source to solve latency problems, but more importantly to reduce bandwidth and costs moving data over WANs and clouds. Next, we consider all the choices in analyzing the data collected. Using the wrong analytic engine may result in useless noise or algorithms that are too resource intensive to run on edge nodes. Next, how will queries from the cloud back to the sensor affect the battery life of the sensor device itself? Add to this litany of choice, and we have to layer on security as the IoT deployment we have built is now the largest attack surface in our city. As you can see, the choices are many and have relationships with one another.

There are now over 1.5 million different combinations of architectures to choose from: