Researches On Key Isuues Of Workflow Management In Service Grid

More and more powerful computing and collaborative Grid applications that require tremendous resources are constructed as Grid service with the development of Grid technology and infrastructure greatly. Many Grid applications are more and more complicated which are constrained by temporal and resource relationship. Grid workflow can conveniently construct, execute, manage and monitor Grid applications, and automate Grid applications with great efficiency. Due to the dynamism, distribution, heterogeneity and autonomy of Grid applications, conventional workflow technology can't effectively solve the relative workflow problems in Grid environment. According to characteristics of service Grid resources and Grid applications, the thesis studies on Grid workflow process model, Grid workflow resource management, Grid workflow fault tolerence mechanism and Grid workflow access control problems on the basis of no considering the Grid resource locations. The detail is as following:Grid workflow process model. The traditional worflow model lack of formal workflow description language to describe the workflow process. The dynamic workflow net named DGWF-Net is proposed based on the workflow net to describe the Grid workflow process, which based on the idea of high level Petri Net. And can solve the problems of expansion, dynamism and multi-selection of Grid process model. And also proposed the Grid workflow verification method based on the Petri Net reduction rules.Grid workflow resource management model. To link the Grid workflow task request with the service resource which require to involve the service registration, service discover, service assignment, and integrate the service to the Grid workflow. For the demand for workflow in Grid environment, a frame of Grid resource management based on workflow engine is put forward. The framework merges Grid service information management component, task parallel analyzer, global resource management and local resource managements into the Grid workflow resource management. Also proposed the global semantic service matching algorithm and local Generic Algorithms based workflow tasks schedule. Grid workflow fault tolerence model. The heterogeneity of the Grid environment and applications, and the dynamic nature of the Grid dictate that a single monolithic failure recovery strategy is not appropriate. We empoloyees the message subscribe-notification mechanism which is based on the interpretation of notification messages being delivered from different entities residing on each Grid node to judge the failue types during the time of Grid workflow executes. And also introduce the high-level recovery policy specification to deal with the failure with the flexibility.Grid workflow access control model. Grid workflow access control is the fundamental issue in workflow security to prevent fraud and errors to access the grid resouce. To solve the problem, in view of decoupling workflow access control model, and proposed a services-oriented Grid workflow access control model, in this model, service means the abstraction of workflow task and which is the instance of workflow task authorization, and also presents the authrization unit. With the workflow context, Authorization enforces separation of duty constraints to support the planning of assigning service to role/users, and the run-time activation workflow tasks.Grid workflow management architecture and prototype. The architecture complying with the standard of WFMC and GCC is open and extensible. The prototype includes Grid workflow user portal, Grid workflow service resource management, Grid workflow engine, Grid workflow fault tolerence component, and Grid workflow access control component. Which is constructed based on Globus Toolset. The experiment of travel service workflow is analyzed.