PROACTIVE MONITORING AND CONTROL OF WORKFLOW EXECUTION IN ADAPTIVE SERVICE-BASED SYSTEMS

Systems based on service-oriented architecture are called service-based systems (SBS), and comprise of computing services offered by various organizations. Users of SBS often require these services to be composed into workflows to perform their high-level tasks. The users usually have certain expectations on the overall QoS (quality of service) of their workflows. Due to the highly dynamic environments of applications of SBS, in which temporary unavailability or quality degradation of services may occur frequently and unexpectedly, monitoring and controlling the execution of workflows adaptively in SBS are needed and should be done in distributed and proactive manner. In this chapter, important research issues and the current state-of-the-art will first be discussed. Then, a virtual machine-based architecture for the execution, monitoring and control of workflows in SBS, and a process calculus for modeling distributed monitoring and control modules are introduced. Using the virtual machine-based architecture and the process calculus, our approach to synthesizing software modules for proactive monitoring and control of workflow execution in SBS is presented.