Exigency-based real-time scheduling policy to provide absolute QoS for web services

• Lucas S. Casagrande USP
• Rodrigo F. de Mello USP
• Ricardo Bertagna USP
• Jose A. Andrade Filho USP
• Francisco J. Monaco USP

Resumo

Telemedicine, distance learning and e-commerce applications impose time constraints directly related to the efficacy of their operations. In order to offer reliability levels capable of meeting such requirements, mechanisms to provide QoS have been widely employed, what motivates this work to propose, implement and validate a real-time scheduling policy for providing absolute QoS for web services. The policy, named Exigency-Based Scheduling (EBS), intends to fast serve the most urgent requests, without degrading the whole system service. The current approach is based on the real-time scheduling, low latency and feedback scheduling, allowing a balanced configuration by the quantification of the exigency imposed to the system by the service classes. The technique evaluation uses metrics proposed in the present work. Experimental results confirm improvements in terms of QoS and client satisfaction.

Palavras-chave: Web services, Quality of service, Delay, Admission control, High performance computing, Telemedicine, Computer aided instruction, Time factors, Real time systems, Contracts