A Study On Open Grid Services Architecture And A GT3-Based Grid Service Implementation

Grid is a kind of new-type network computing platform appearing after World Wide Web , The purpose is for offering to user and sharing the infrastructure of different resources including Web page in an all-round way . Through integrating the scattered resources that lie in different geographical position, users needn't understand the infrastructure detail of resources when they use resources that they require. Distributed resources and network communication are physics foundations of Grid.[4] The term Grid was originally used in analogy to other infrastructure(such as electrical power) grids. People hope ,when they use network resources, they can use them freely just like using the electric power resource, But needn't care about electric power resources that used now are hydroelectric generation or nuclear power one , from which power plant that it is. The network hopes computing capability in common use that provided for end user is to have nothing to do with the geographical position and concrete calculation facilities. Internet offers the E-mail, Web page to people mainly, but Grid can offer more stronger functions . It makes people share resources of the computer , store resources and other resources. Someone regards Grid as future Internet. The foreign media often describe the relevant technology of Grid with "Internet of future generation ", "WWW of future generation",etc. Because Grid technologies and Web services have much in common on technology and goal. In 2002,the globus Project and IBM's Open Service Architecture group have proposed the Open Grid Services Architecture(OGSA).OGSA is a Grid Architecture that is oriented service. It regards service as the center. Abstractly everything is service .Web services often face the persistent services, but in the Grid environment , there are a lot of temporary services, that is to say ,they are transient. Grid Service is a kind of special Web service. It provides some standard interfaces in accordance with the Grid service criterion. These interfaces provide discovery of service , dynamically creating service, lifetime management, information subscription, delivering notification ,security management , etc. Open Grid Services Infrastructure(OGSI) is a kind of infrastructure which build OGSA. It is the formal implementation about the concepts of OGSA. The core is the Grid service criterion. The criterion defines standard behaviors and interfaces of Grid services based on Web service .OGSI is also described by WSDL, but the elements that defined by WSDL did not describe enough characters of Grid service . Certain extensions to WSDL are proposed by OGSI. In which define new properties about portType. This extension of WSDL is called Grid Services Description Language. The Globus Toolkit 3 is a first platform that supports OGSA and OGSI. It supports that the Web services are the platform of data transformation. It mainly includes Core, Security Services, Base Services, Data Services and Other Grid Service. On the Grid environmental platform of GT3, the process that usually programs a Grid service is mainly five steps: 1 , Offering a service interface that mainly provides the interface describe file. This usually has two kinds of methods to implement:(1)transforming through the simple Java interface ; (2)Programming directly the web service describe language WSDL file, we adopt extending describes file GWSDL in GT3. 2, Programming the service implementation with Java. 3, Programming the deployment describe file WSDD. 4, Creating the GAR file with ANT tool. 5, Deploying the service in the container .When we have deployed a Grid service ,we start the service in the container. Through a client procedure that we programmed ,we can test it whether the Grid service run proper. In this paper, this Grid service MaxService offers the following simple function: (1)Maximum method: Through comparing the input data of client and the saved data of server, the method saves the bigger into the variable "value";(2) sum method: the method is that add the input data of client to the saved data of server, then saves the result into the variable "value";(3)getVale method: the method return the variable "value"to the caller. Through in this Grid service gradually increasing delivering notification , lifetime management ,log , security service ,etc . we can improve MaxService and make it seem like a real Grid service. Through programming and deploying this MaxService service , we have more overall understand to the Grid application on GT3 platform, and are familiar with the programming process of Grid services. In this paper, I program the Grid service mainly by utilizing the GT3 Core and Security Services. We can write out better grid service on the basis of this ,such as increasing the Graphical User Interface of Input and Output ,and increasing the job management ,etc. With the release of GT4 based on WSRF ,we could believe that Grid technology is developed with higher speed...