Affiliations: Institute of Scientific Computing, University of
Vienna, Nordbergstraße 15, 1090 Vienna, Austria
Note: [] Corresponding author: I. Brandic, Institute of Scientific
Computing, University of Vienna, Nordbergstraße 15, 1090 Vienna, Austria.
Tel.: +43 1 4277 39408; Fax: +43 1 4277 9394; E-mail: brandic@par.univie.ac.at
Abstract: Many important scientific and engineering problems may be solved by
combining multiple applications in the form of a Grid workflow. We consider
that for the wide acceptance of Grid technology it is important that the user
has the possibility to express requirements on Quality of Service (QoS) at
workflow specification time. However, most of the existing workflow languages
lack constructs for QoS specification. In this paper we present an approach for
high level workflow specification that considers a comprehensive set of QoS
requirements. Besides performance related QoS, it includes economical, legal
and security aspects. For instance, for security or legal reasons the user may
express the location affinity regarding Grid resources on which certain
workflow tasks may be executed. Our QoS-aware workflow system provides support
for the whole workflow life cycle from specification to execution. Workflow is
specified graphically, in an intuitive manner, based on a standard visual
modeling language. A set of QoS-aware service-oriented components is provided
for workflow planning to support automatic constraint-based service negotiation
and workflow optimization. For reducing the complexity of workflow planning, we
introduce a QoS-aware workflow reduction technique. We illustrate our approach
with a real-world workflow for maxillo facial surgery simulation.
Keywords: Quality of Service (QoS), location affinity, workflow reduction, workflow planning, UML-based Grid workflow specification
