doc: Edge use cases (#984)

akka-edge-docs/src/main/paradox/use-cases.md

@@ -1,4 +1,53 @@
 # Example Use Cases
 
-## FIXME
+## Vehicle communications
+
+There are many use cases for having vehicles communicate with each other, or with local devices such
+as traffic lights, information signs, distribution points, either in a single geographic area or a wide area:
+
+* Traffic coordination and status reporting
+* Support self-driving vehicles with AI decisions
+* Fleet tracking, coordination and communication
+
+The communication between the vehicles and local devices would not be point-to-point, but via a local PoP (point of presence). Akka Edge
+would be great for implementing this PoP service. It can not only manage the communication between the devices in the
+area, but also aggregate or filter information of importance and send that to more central cloud services. It can
+receive information from cloud services and propagate relevant information to the devices.
+
+The benefits of having vehicles in an area communicate locally with each other and devices instead of through the cloud include:
+
+* Isolation from wider area network faults
+* Communication can be far more chatty without overwhelming ingress/egress in the cloud, allowing much higher scales
+* Much lower latencies
+
+## High availability retail
+
+Retail systems need to be highly available. One of the biggest problems that retail systems have in achieving this is
+that the times that they are most important (that the company stands to lose the most revenue if they go down) are the
+times when they are most likely to go down, because the surge in load due to the surge in shoppers often makes the
+system unstable.
+
+Isolation is an effective way to address this, if one part of the system serving one geographic area is overloaded,
+and it fails, while not ideal, the damage is limited if that doesn’t affect other geographic areas. This can be
+achieved by using PoPs close to, or even in, the retail outlets themselves.
+
+One challenge with this is data that moves around. A shopper might browse online first, then go to one store, and
+maybe go to another store if they find the stock they want isn’t there. Having this users profile follow them,
+so that a “virtual shop assistant” can guide them to get the right help they need in store, without relying
+on the availability of a central system, would enable seamless experiences even under load.
+
+## Sporting events
+
+Real-time, interactive applications for a sports event can offer a much more enriching experience. Augmented reality
+of a game require low latency for real-time updates. Quick access to rules of the game and facts about the players 
+may also be of importance for a nice interactive experience. Many people gathered at the same place is demanding
+for the communication infrastructure and the backend systems. Local services running at the sports arena would
+be a good use case for Akka Edge.
+
+## Factories
+
+Local compute power to analyze images and videos to quickly detect abnormalities in the manufacturing process. Machine
+learning can be shared between factories. Telemetry data can be gathered, aggregated and analyzed by cloud services
+to find how the process can be improved.
+