基于WSRF的网格空间服务及其管理

网格技术与空间信息技术的结合,产生了空间信息网格。空间信息网格能够汇集各种空间信息资源,进行一体化管理,支持资源共享,提供"按需服务"的能力。"按需服务"要求能根据用户的要求,提供多样性服务,即能自动发现所有满足用户需求的空间信息资源或其组合,并评估各个资源或其组合,按一定目的选择资源,提供服务。但是由于网格的动态性,使得使用者较难得到现势性很好的空间信息资源的信息,直接影响了空间信息网格"按需服务"的能力。将传统的空间信息服务技术直接融入网格不能解决这一问题。为了解决该问题,提高"按需服务"的可靠性,本文根据支持资源状态和服务分离的网格框架W SRF,提出了W SRF设计网格空间服务及其管理的方案。即在空间信息资源节点,除了将信息资源以标准服务的方式提供使用,还以W SRF的方式组织资源的状态并提供访问和订阅;网格中央节点收集、维护和管理各子节点的服务和资源状态信息,提供信息访问接口以支持"按需服务"所必需的资源选择。最后按照该方案实现了一个简单的空间数据网格。

Spatial Information Grid Services Based on WSRF and Their Management

Applying grid into spatial information area forms the Spatial Information Grid.Spatial Information Grid can aggregate kinds of spatial information resources,perform integrative management,support resource share and provide ＂on-demand services＂.＂Service on-demand＂ means to provide diverse services according to the requirements of users,that＇s to discover spatial information resources or their combinations that satisfy the users＇ requests,then evaluate them and choose the best ones following some goals to provide service.However,the dynamism of grid environment makes it difficult for users to get current information of the distributed spatial information resources,and reduce the ability to provide reliable ＂on-demand service＂.Directly applying the traditional spatial information services into grid cannot overcome this issue.To improve this situation,the plan to design spatial grid services and their management services based on WSRF（Web Service Resource Framework）,which is ＂a generic and open framework for modeling and accessing stateful resources using Web services＂ and support the separation of states and services is given.The plan is composed of two parts,namely spatial information grid services and the management service.The spatial information grid services are deployed at the nodes that contribute spatial information resources by providing standard accessing services and at the same time organize and publish the state of the resources to be accessed or subscribed following WSRF.The key technologies of how to design the services and the WS-Resource are discussed.The management service is deployed at center node which collects,maintains and manages the information of services and resource state of child nodes and provides access interface to support the resource selection which is necessary for ＂on-demand service＂.At last a spatial data grid implementing the plan is described.The spatial data grid contains three kinds of services,they are spatial data grid service,spatial computing grid service and management service.In spatial data grid service,the interfaces are organized complying WFS and four kinds of WS-Resource（service,request,loading and spatial data） are designed.Like spatial data grid service,the interfaces are organized complying WPS and four kinds of WS-Resource（service,request,loading and spatial algorithms） in the spatial computing grid service.The management service is made up of three parts： service register management module,sources and services information management module and public thematic service.