These are also event-driven applications. Predominantly, instead of service orchestration, service choreography is preferred for building event-driven applications. As per the Reactive manifesto, reactive applications have to have the following characteristics. They have to be responsive, resilient, elastic, and message-driven. Reactive systems are bound to respond instantaneously to any kind of stimulus. This is just opposite to the traditional request and response (R and R) model, which is generally blocking. This pattern turns out to be an excellent way for using the available resources in a better manner. Also, the system responsiveness gets a strong boost. Instead of blocking and waiting for computations to be finished, the application starts to handle other user requests in an asynchronous manner to make use of all the available resources and threads.