An Adaptive Quality of Service Aware Middleware for Replicated Services

Sudha Krishnamurthy, William H. Sanders, Michel Cukier

Research output: Contribution to journalArticlepeer-review


A dependable middleware should be able to adaptively share the distributed resources it manages in order to meet diverse application requirements, even when the quality of service (QoS) is degraded due to uncertain variations in load and unanticipated failures. In this paper, we have addressed this issue in the context of a dependable middleware that adaptively manages replicated servers to deliver a timely and consistent response to time-sensitive client applications. These applications have specific temporal and consistency requirements, and can tolerate a certain degree of relaxed consistency in exchange for better response time. We propose a flexible QoS model that allows clients to specify their timeliness and consistency constraints. We also propose an adaptive framework that dynamically selects replicas to service a client's request based on the prediction made by probabilistic models. These models use the feedback from online performance monitoring of the replicas to provide probabilistic guarantees for meeting a client's QoS specification. The experimental results we have obtained demonstrate the role of feedback and the efficacy of simple analytical models for adaptively sharing the available replicas among the users under different workload scenarios.

Original languageEnglish (US)
Pages (from-to)1112-1125
Number of pages14
JournalIEEE Transactions on Parallel and Distributed Systems
Issue number11
StatePublished - Nov 2003


  • Middleware
  • Probabilistic modeling
  • Quality of service
  • Replica consistency
  • Timeliness

ASJC Scopus subject areas

  • Signal Processing
  • Hardware and Architecture
  • Computational Theory and Mathematics


Dive into the research topics of 'An Adaptive Quality of Service Aware Middleware for Replicated Services'. Together they form a unique fingerprint.

Cite this