Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Computer Science

First Advisor

Rajeev R. Raje

Second Advisor

Antony Hosking

Committee Chair

Rajeev R. Raje

Committee Co-Chair

Antony Hosking

Committee Member 1

Murat Dundar

Committee Member 2

Zhiyuan Li

Committee Member 3

Mihran Tuceryan


The objective of this dissertation is to propose a comprehensive framework to predict the QoS and trust (i.e, the degree of compliance of a service to its specification) values of composed distributed systems created out of existing quality-aware services. We improve the accuracy of the predictions by building context-aware models and validating them with real-life case studies. The context is the set of environmental factors that affect QoS attributes (such as response time and availability), and trust of a service or a composed system. The proposed framework uses available context-QoS dependency information of individual services and information about the interaction patterns among the services to make predictions for the QoS and trust values of the composed system at the design phase of the development lifecycle. Such predictions made in the early phases of the system development lifecycle will reduce cost, time, and effort. We demonstrate the use of these predictions in selecting the optimum set of services to create composed systems using heuristic optimization algorithms. Additionally, the prediction model is used at runtime with fast heuristic techniques to build adaptable composed systems. The empirical results show the proposed context-dependent framework performs well in providing more accurate predictions than the prevalent approaches.