The system stays responsive under varying workload. Reactive Systems can react to changes in the input rate by increasing or decreasing the resources allocated to service these inputs. This implies designs that have no contention points or central bottlenecks, resulting in the ability to shard or replicate components and distribute inputs among them. Reactive Systems support predictive, as well as Reactive, scaling algorithms by providing relevant live performance measures. They achieve elasticity in a cost-effective way on commodity hardware and software platforms.
Elastic
Resource Contention is a conflict over access to a shared resource
Reactive composition of stateless nano-services
Request a random number that is around 5
Make that many requests to a random word service
Return the random string of gibberish