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Abstract

This article proposes the Implicit Packet Meta Header (IPMH) as a standard method to compute and represent common QoS properties of the Application Data Units (ADU) of multimedia streams using legacy and proprietary streams headers (e.g. Real-time Transport Protocol headers). The use of IPMH by mechanisms located at different layers of the communication architecture will allow implementing fine per-packet self-optimization of communication services regarding the actual application requirements. A case study showing how IPMH is used by error control mechanisms in the context of wireless networks is presented in order to demonstrate the feasibility and advantages of this approach.

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Abstract

The accelerated development of Internet has facilitated the design and deployment of a large diversity of distributed applications and network technologies. The dramatic evolution of application requirements and network services has deeply impacted the traditional transport layer and different approaches have been followed in order to cope with this new context. Proposed solutions have been mainly based on partial enhancements to existing protocols or the redesigning of completely new protocols. However both approaches fail in offering an extensible framework able to easily integrate existing transport mechanisms and protocols. Moreover, this framework should easily incorporate future components aimed at satisfying new application requirements and to deal with new network services and technologies. This paper presents an autonomic transport protocol framework providing a flexible service component architecture offering self-configuring and selfoptimizing functionalities intended to application and transport protocol designers.

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Abstract

This paper presents a framework of architecture-centric models to support the automated and adaptive deployment of communication services for QoS-enabled end-to-end group communication systems. The Transport level (TCP, UDP level) and the above messaging Middleware level are considered as the two communication levels targeted by the QoS-driven adaptation process. Application to crisis management systems (CMS) is considered as a case study from the more general domain to which our results apply: cooperative activity support systems. The adaptation rules rely on graph matching and graph rewriting. The adaptation enactment is based on the dynamic composition of micro-protocols at the Transport level and on the dynamic binding of software components and services at the Middleware level. The deployment model is used as a central feature of service provisioning. The influence of the cooperation and the communication contexts is expressed and maintained consistent by automated graph-based model refinement and transformation.

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Abstract

Self-adaptation of communication protocols is a major issue in the conception of future services for the ambient Internet. These protocols will have to provide adequate services to complex, mobile, cooperative application with dynamic requirements distributed in highly heterogeneous environments, partially wireless and ad hoc with variable and evolutive constraints. In this highly dynamic context, providing efficient solutions requires handling adaptability not only at the behavioral level, but also at the architectural level. End-to-end modular architecture protocols are a promising solution to support architectural self-adaptation to the context. Following this approach, the contributions presented in this paper address the automated choice of internal architecture for configurable transport level protocols. Tackling this need by means of informal models may lead to non generic and suboptimal solutions due to the complexity of the problem. We propose to guide adaptation by an analytical model which is then evaluated against simulation results.

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Abstract

In the context of multimedia and real-time systems, this article introduces a generic interpreter of QoS properties (xQoS-Interpreter) for the Application Data Units (ADUs) composing standard and proprietary multimedia streams. This approach is intended to make the QoS properties of ADUs publicly available to any mechanism of the underlying communication system. The use of this information allows for cross-layer QoS optimization of the communication services taking the actual per-packet requirements of the applications into account. A case study showing how the xQoS-Interpreter is used at transport layer to seamlessly optimize the perceived QoS of an end-to-end video transmission is presented. In this scenario, the xQoS-Interpreter is used to optimize a TCP-friendly Rate Control mechanism (TFRC) over congested wireless network services in order to demonstrate the feasibility and advantages of our approach.

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Résumé

L'auto-adaptation des protocoles de communication est un enjeu majeur dans la conception des futurs services de l'Internet ambiant. Ceux-ci auront en effet à répondre aux besoins dynamiques d'applications complexes, mobiles et coopératives, distribuées dans des environnements réseaux hétérogènes, en partie sans fil et ad hoc, aux contraintes variables et évolutives. Dans ce nouveau contexte, dynamique à différents niveaux, les protocoles de bout en bout à architecture modulaire apparaissent comme un support privilégié pour l'auto-adaptation au contexte. Les contributions présentées dans cet article s'inscrivent dans cette approche et adressent le problème du choix d'architecture interne des protocoles auto configurables. Partant des propositions de protocoles à architecture modulaire issues des travaux de recherche actuels, nous proposons un modèle analytique pour guider le processus de décision, que nous confrontons ensuite, au travers d'un cas d'étude, à des mesures des performances réalisées sur une plateforme d'évaluation de protocoles à architecture configurable.

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