Lifetime service level agreement management for service composition

This thesis presents a set of technologies supporting service level agreement (SLA) management for service composition in the service-oriented computing (SOC) environment. Its purpose is to tackle some of the existing problems in the research on quality of service (QoS) aware service composition. The QoS guarantee throughout the process of service provision is a critical and challenging issue, especially in the service composition scenarios where a group of component services compose a composite service. As services are considered merchandises on the Internet, the quality of a service is as important as, if not more than, the functionality of the service. SLAs can be used to specify service consumers' QoS requirements and service providers' QoS promises. A set of supporting technologies are proposed in this thesis to address the major issues of QoS-aware service composition that arise at different stages of the lifetime of SLAs: establishment, enforcement and completion. Specifically, an innovative SLA negotiation approach is proposed to support SLA establishment at build time based on combinatorial auctions; a new SLA adaptation approach is proposed to support SLA enforcement at runtime; and a novel trust system is proposed to support reputation-oriented service selection based on SLA profiling upon SLA completion at completion time. Experimental results shows that our approaches 1) effectively improve the quality of the composite service through SLA negotiation; 2) significantly improve the satisfaction rates of service consumers' QoS requirements for the composite services through SLA adaptation; and 3) remarkably improve the success rate of composite services and well resist the unique threats in the open SOC environment through SLA profiling. The major contribution of this research is to provide a comprehensive and integrated solution to lifetime SLA management for service composition in the open SOC environment. With the new approaches developed, the quality of the composite services can be guaranteed at different stages of the lifetime of the composite services: build time, runtime and completion time.