Quality of Service and Semantic Workflow Composition

Department of Computer Science
University of Georgia



Semantics are critical to support the next generation of the Web. The important contribution of the “Semantic Web”, vis-à-vis the current Web, is the ability to represent and process descriptions of every resource on the Web. A resource description, informally called its “semantics”, includes that information about the resource that can be used by computers - not just for display purposes, but for using it for automatic processing in various applications.

    Our work focuses on two issues: semantic Web services and process composition. Semantic Web services are Web services with a formal description (semantics) that can enable a better discovery, selection, composition, monitoring, and interoperability. Processes are next steps to carrying out core business activities, such as e-commerce and e-services, and are created from the composition of Web Services or other components.

    This work is about associating semantics to Web Services, and exploiting it in process composition. The composition process involves a functional perspective and an operational perspective. The functional perspective involves Web Service Discovery, addressing semantic heterogeneity handling. The operational perspective takes form of the research on QoS specification for Web Services and Processes.


Quality of Service

Workflow management systems (WfMSs) have been used to support a variety of business processes. As organizations adopt new working models, such as e-commerce, new challenges arise for workflow systems. These challenges include support for the adequate management of quality of service (QoS) and the development of new solutions to facilitate the composition of workflow applications involving Web services. The good management of QoS directly impacts the success of organizations participating in e-commerce activities by better fulfilling customer expectations and achieving customer satisfaction.

    To enable adequate QoS management, research is required to develop mechanisms that specify, compute, monitor, and control the QoS of the products or services to be delivered. The composition of workflows to model e-service applications differs from the design of traditional workflows due to the number of Web services available during the composition process and to their heterogeneity. Two main problems need to be solved: how to efficiently discover Web services and how to facilitate their interoperability.

    To enhance WfMSs with QoS management, we have developed a QoS model that allows for the description of nonfunctional aspects of workflow components, from a quality of service perspective. To automatically compute the overall QoS of a workflow, we have developed a mathematical model and implemented an algorithm (SWR algorithm). Our QoS model and mathematical model have been validated with the deployment and execution of a set of production workflows in the area of genetics. The analysis of the collected data proves that our models provide a suitable framework for estimating, predicting, and analyzing the QoS of production workflows.


Workflow Composition

To support, facilitate, and assist the composition of workflows involving Web services, we present a solution based on ontologies. We have developed an algorithm that workflow systems and discovery mechanisms can use to find Web services with desired interfaces and operational metrics, and to assist designers in resolving heterogeneity issues among Web services. Our approach provides an important solution to enhance Web service discovery and interoperability.

Index words: workflow management systems (WfMSs), quality of service (QoS), workflow composition, web services, business process management.


Cardoso, J. (2002). Quality of Service and Semantic Composition of Workflows. Ph.D. Dissertation. Department of Computer Science, University of Georgia, Athens, GA. [PPT presentation].

Cardoso, J., J. Miller, A. Sheth and J. Arnold (2002). "Modeling Quality of Service for Workflows and Web Service Processes." the Very Large Data Bases Journal submitted.

Cardoso, J. and A. Sheth (2002). "Implementing QoS Management for Workflow Systems." International Journal of Cooperative Information Systems (IJCIS) submitted.

Cardoso, J. and A. Sheth (2002). Process Quality of Service Specification. EI3-IC workshop at NIST, Gaithersburg, MD.

Cardoso, J. and A. Sheth (2002). "Semantic e-Workflow Composition." Journal of Intelligent Information Systems (JIIS). submitted.

Cardoso, J., A. Sheth and J. Miller (2002). Workflow Quality of Service. International Conference on Enterprise Integration and Modeling Technology and International Enterprise Modeling Conference (ICEIMT/IEMC’02), Valencia, Spain, Kluwer Publishers.

Chandvasekavan, S., G. Silver, J. A. Miller, J. S. Cardoso and A. P. Sheth (2002). Composite Web Service: Performance Evaluation and Simulation. Proceedings of the 2002 Winter Simulation Conference, San Diego, California (in progress).

Kochut, K., J. Arnold, A. Sheth, J. Miller, E. Kraemer, B. Arpinar and J. Cardoso (2002). "IntelliGEN:  A Distributed Workflow System for Discovering Protein-Protein Interactions."

Miller, J. A., J. S. Cardoso and G. Silver (2002). Using Simulation to Facilitate Effective Workflow Adaptation. Proceedings of the 35th Annual Simulation Symposium (ANSS'02), San Diego, California. pp. 177-181.

Sheth, A., J. Cardoso, J. Miller and K. kochut (2002). Service-oriented Middleware. 6th World Multiconference on Systemics, Cybernetics and Informatics (SCI 2002), Orlando, FL.