Responsiveness

Responsiveness as a concept of computer science refers to the specific ability of a system or functional unit to complete assigned tasks within a given time. In the Reactive principle, Responsiveness is one of the fundamental criteria along with resilience, elasticity and message driven. It is one of the criteria under the principle of robustness. The other three are observability, recoverability, and task conformance. Software which lacks a decent process management can have poor responsiveness even on a fast machine. On the other hand, even slow hardware can run responsive software. It is much more important that a system actually spend the available resources in the best way possible. For instance, it makes sense to let the mouse driver run at a very high priority to provide fluid mouse interactions. For long-term operations, such as copying, downloading or transforming big files the most important factor is to provide good user-feedback and not the performance of the operation since it can quite well run in the background, using only spare processor time. Long delays can be a major cause of user frustration, or can lead the user to believe the system is not functioning, or that a command or input gesture has been ignored.