Analysis of QoS in cooperative services for real time applications

Abstract

Future complex architectures for Web-Services-based delivery of services and objects require applications able to deal with different levels of Quality of Service (QoS) and able to describe also the quality of the associated object. In order to allow applications adapting in front of degraded quality in a pre-determined way, all the nodes participating in a given business process shall coordinate their efforts in (i) deciding how to deal with service degradation/disruption, and in (ii) managing the overall quality (i.e., not only the Web-Service QoS but also the quality of the objects being delivered through the cooperative process). According to this rationale, one of the main goals of the Quadrantis project has been to investigate how to provide combined quality measurement of services and delivered objects, such as videos, voice, texts, or images. QoS modelling and management according to users’ needs are presented. Users will access services according to QoS Contracts negotiated with service providers, while the streaming content is based on user profiles, to face a more dynamic management of QoS deviations in the Real Time provisioning level. In our approach, applications can request QoS, and react and repair to violations of the terms set forth in contracts or in expected delivery parameters, such as bandwidth or frame rate. To this extent, we present a framework for providing applications and services with QoS adaptation functionality, through the step-wise induction of a monitoring and recovery solutions at both Web-Services and streaming layers. The foundations of the merging between the two layers, which deal with very different aspects and protocols, are based on quality.