Most applications from a few years back had the luxury of the following:
- Multi-second response times
- Multiple hours of offline maintenance
- Smaller volumes of data
Times have changed. New devices (mobiles, tablets, and so on) and newer approaches (cloud-based) have emerged. In today's world, we are talking about:
- Sub-second response times
- 100% availability
- An exponential increase in data volumes
Different approaches have emerged during the last few years to meet these emerging challenges. While reactive programming is not really a new phenomenon, it is one of the approaches that have been successful in dealing with these challenges.
The Reactive Manifesto (http://www.reactivemanifesto.org) aims to capture common themes.
We believe that a coherent approach to systems architecture is needed, and we believe that all necessary aspects are already recognised individually: we want systems that are Responsive, Resilient, Elastic and Message Driven. We call these Reactive Systems.
Systems built as Reactive Systems are more flexible, loosely coupled, and scalable. This makes them easier to develop and amenable to change. They are significantly more tolerant of failure, and when failure does occur, they meet it with elegance rather than disaster. Reactive Systems are highly responsive, giving users effective interactive feedback.
While the Reactive Manifesto clearly states the characteristics of responsive systems, it is not as clear on how Reactive Systems are built.