So, what is the Reactive Manifesto? The Reactive Manifesto (http://www.reactivemanifesto.org) is a document defining the four reactive principles. You can think of it as the map to the treasure of reactive programming, or like the bible for the programmers of the reactive programming religion.

Everyone starting with reactive programming should have a read of the manifesto to understand what reactive programming is all about and what its principles are.

So, the following is the gist of four principles that Reactive Manifesto defines:

• Responsive:
  The system responds in a timely manner. Responsive systems focus on providing rapid and consistent response times, so they deliver a consistent quality of service.
• Resilient:
  In case the system faces any failure, it stays responsive. Resilience is achieved by replication, containment, isolation, and delegation. Failures are contained within each component, isolating components from each other, so when failure has occurred in a component, it will not affect the other components or the system as a whole.
• Elastic:
  Reactive systems can react to changes and stay responsive under varying workload. They achieve elasticity in a cost effective way on commodity hardware and software platforms.
• Message driven:
  In order to establish the resilient principle, reactive systems need to establish a boundary between components by relying on asynchronous message passing.

By implementing all four preceding principles, the system becomes reliable and responsive thus, reactive.