Runtime Adaptability driven by Negotiable Quality Requirements

TL;DR

This paper presents a novel approach for runtime adaptability in service-oriented systems, enabling dynamic variant selection based on user preferences and real-time QoS changes through a model-driven, negotiable quality requirements framework.

Contribution

It introduces a new method for detecting QoS changes, updating system models, and selecting optimal variants using negotiable maintenance goals to express user preferences.

Findings

Effective detection of QoS variations at runtime

Automated interpretation of user quality preferences

Improved variant selection aligning with user goals

Abstract

Two of the common features of business and the web are diversity and dynamism. Diversity results in users having different preferences for the quality requirements of a system. Diversity also makes possible alternative implementations for functional requirements, called variants, each of them providing different quality. The quality provided by the system may vary due to different variant components and changes in the environment. The challenge is to dynamically adapt to quality variations and to find the variant that best fulfills the multi-criteria quality requirements driven by user preferences and current runtime conditions. For service-oriented systems this challenge is augmented by their distributed nature and lack of control over the constituent services and their provided quality of service (QoS). We propose a novel approach to runtime adaptability that detects QoS changes, updates the system model with runtime information, and uses the model to select the variant to execute at runtime. We introduce negotiable maintenance goals to express user quality preferences in the requirements model and automatically interpret them quantitatively for system execution. Our lightweight selection strategy selects the variant that best fulfills the user required multi-criteria QoS based on updated QoS values.