A Mobile Agent Infrastructure for QoS Negotiation of Adaptive Distributed Applications

Abstract

Abstract. QoS-aware distributed applications such as certain Multimedia and Ubiquitous Computing applications can benefit greatly from the provision of QoS guarantees from the underlying system and middleware infrastructure. They must avoid execution glitches that affect the user's perception of the application output. Most research in QoS support for distributed systems focuses on three aspects of QoS management: admission control, resource reservation, and scheduling. However, in highly dynamic distributed environments, effective means for QoS negotiation and re-negotiation are also essential. We believe that mobile agents, due to its inherent flexibility and agility, can play an important role in this scenario, specially during the application adaptation process. We designed a mobile-agent-based infrastructure that provides services such as resource monitoring, QoS brokering, and QoS enforcement. Furthermore, our infrastructure offers a powerful mechanism for QoS negotiation. In this paper, we describe the architecture and prototype implementation of this infrastructure. First, we discuss the motivations and related works. We, then, present the architectural design and discuss implementation issues concerning the infrastructure prototype. Finally, we introduce a sample application called ReflectorAglet -a QoS-aware adaptive audio reflector -and present preliminary experimental results. MotivationMultimedia applications (such as video and audio streaming) and Ubiquitous Computing services are examples of distributed applications that have a clear need for quality of service guarantees. The success of this class of applications is tightly related to the user's level of satisfaction. These systems must avoid, at all costs, performance losses that might affect the user's perception of the application output. As a consequence, QoS-related services have become an important part of the infrastructure of distributed systems to enable the development of applications such as the ones described above.