TIMELY AND DEPENDABLE QoS ADAPTATION IN QUASI-SYNCHRONOUS SYSTEMS
Carlos Almeida · International Journal of Computers and Applications · 2011
AbstractMost distributed communication infrastructures are not fully synchronous. They are at most quasi-synchronous: only a small part of the system can be considered as synchronous; the rest presents a more dynamic behaviour where the duration of a given activity (processing or communication) is usually relatively small, but there is a non-null probability of taking a much higher value occasionally. In these scenarios, it is very difficult (or even impossible) to always offer the desired timeliness properties. However, some applications need more than just a best-effort policy. They need at least the ability to adapt the offered quality of service (QoS) in a timely and consistent way. In the quasi-synchronous approach, the small synchronous part is used to build components able to control and validate the other parts of the system. This approach does not solve all timeliness problems per se, but can be used by applications to reach a safe state before stopping, or switch in a controlled manner between s...