Research On Service Composition Of Geographic Modeling Based On Grid Workflow

Grid technology is a new generation of Internet computing model following thetraditional Internet, Web service. With the increasing of grid nodes and its services,geo-application with compute-intensive and data-intensive need to be supported urgentlyby high performance grid and a large number of atom geo-services. Therefore, amechanism needed to coordinate the running among services in order to meet thegeo-application. Grid workflow can construct grid application, implement the servicecomposition and invoke through defining business process by human-computer interaction.This paper relied on the team’s geographic knowledge service grid-GeoKSGrid, taking theMeizhou gulf marine soluble liquid pollution spreading simulation service as a instance,based on grid middlemare-Globus Toolkit4.0, studies The service composition ofgeographic modeling based on grid workflow which can composite the services of singlefunction to advanced complex services according to need, thus reducing the repeateddevelopment, improving share level and composition ability. The main results aresummarized as follows:Firstly, based on the comparison of grid architecture-OGSA and WSRF, grid serviceand web service, sum up the two main methods-service composition based on AI andservice composition based on process, analyze the typical representative of the twomethods-service composition based on semantic and workflow. Describe the web servicecomposition criterions and elaborate the composition standard-Business Process Executionlanguage (BPEL) and its key element and execution engine.Secondly, design and implement the service composition subsystem based on gridworkflow which relies on team’s geographic knowledge service grid-GeoKSGrid. Analyzethe function of subsystem in the grid，propose the system architecture which consist of userinterface module, flow execution module and grid service resource module. Design everymodule’s function in detail based on the system architecture. Describe the systemexecution process which contains grid service package and deployment, workflow processmodeling, process model deployment and process model execution.Thirdly, take marine soluble liquid pollution spreading simulation service as instance,design and implement geographic modeling service. Describe the pollution simulation model; propose the decomposition principle which is independence between atom modeland application, convenience of dynamic composition according to structure of pollutionspreading simulation service. The basic idea is that decompensate the entire model,package the every sub model into grid service and deploy it into grid node.Finally, integrate the system into team’s grid system-GeoKSGrid,.study theapplication of geographic modeling service composition based on grid workflow. Theapplication shows that grid services can be composted according to user needs throughguidance and control of grid workflow. The composition result can resolve more complexpractical application, increase the flexibility and range of services, and achieve the targetthat can resolve more complicated application through service composition.