Abstract: As a special kind of "programming" technology for constructing problem-solving applications on the basis of grid resources, grid workflow has been widely applied. Methodologies for ensuring ddependability of grid workflows have attracted attention. However, it remains a challenge how to evaluate the effectiveness of these methodologies due to the complexity and uncertainty of grid environments. Based on VINCA grid workflow, key factors that affect the depen dability were systematically analyzed, and a general component model and dependability attributes model for grid work- flow systems were established. A configurable and extensible simulation toolkit called VINCASim for evaluating the dependability of grid workflows was developed based on GridSim. The toolkit can simulate various failures raised from grid nodes, workflow engines, network connection and workflow execution in a configurable manner, and supports incorporating different dependability ensuring methods programmatically. Thus, a controllable and repeatable experiment platform was provided for evaluating different methods. The usability was demonstrated by a use case scenario.

Key words: Grid workflow, Dependability, Simulation