Study And Implementation Of Grid Workflow System For Numerical Weather Prediction Application

The operation of Numerical Weather Prediction in grid environment is an extremely complex process of computation. The traditional method of manually controlling prediction process by script is not flexible or explicit, and has high requirement of users'knowledge.In this paper, we research the workflow system of Numerical Weather Prediction in grid environment. Aimed at the requirement of Numerical Weather Prediction System, we study the key techniques from the Numerical Weather Prediction's aspects of process characteristics, process scheduling and implementation policy, and fault-tolerance mechanism.Here we analyze the characteristics of the process. And we design a pattern of Web service components combination, which is appropriate for Numerical Weather Prediction. Moreover, this paper specifies how to use the technique of grid workflow to create the architecture of Numerical Weather Prediction in grid environment.Based on the research of related techniques of grid workflow engine, we present a method of designing a grid workflow engine in the area of Numerical Weather Prediction. While scheduling and implementing the workflow, this paper put forward an approach to bind specific services dynamically during the process to enable users solving the problems of heterogeneity and variability while implementing resources in grid environment, which brings great flexibility into the process and adapts the characteristic of dynamic variety in grid environment. Furthermore, this paper presents two levels of scheduling mechanism, which separates the service scheduling task in prediction service from the workflow engine scheduling task, and simplifies the work of workflow engine.Because of the large number of data in Numerical Weather Prediction and the long running time of it, and considering the distributing and dynamics of networks and the increasing probability of failure in the implementation of process, this paper presents two levels of fault-tolerance mechanism to deal with abnormities during the implementation. Demonstrated by analysis and practice, this mechanism improves system's reliability.In the aspect of realization, this paper carries out the workflow prototype system EPGFLow under grid environment. Based on the open software ActiveBPEL, we design the workflow engine of this prototype system. Furthermore, we research the means of integrating this system with the open portal frame GridSphere.