Architecture
gUSE is implemented as a set of Web services that bind together in flexible ways on demand to deliver user services in Grid and/or Web services environments. User interfaces for gUSE services are provided by the WS-PGRADE Web application. WS-PGRADE is a Web portal hosted in a standard portal framework. WS-PGRADE uses the client APIs of gUSE services to turn user requests into sequences of gUSE specific Web service calls. WS-PGRADE hides the communication protocols ans sequences behind JSR168 complient portlets. End users can access WS-PGRADE via Web browsers. A graph editor component can be downloaded from WS-PGRADE via the browser to the user machine. The editor can be used to define the static skeleton of workflows, while the HTML pages of WS-PGRADE provide interfaces to add content to graphs, to generate complete Grid/Web service applications.
gUse services can be hosted on a single host or can be distributed over several server machines to optimize resource usage or increase performance. gUSE services provide data services (user database, proxy credential database, application code database, workflow database, application history and change log database, etc.) and control services (e.g. job submission, workflow enactment, etc.). gUSE services discover each other using a central gUSE service, the information system.
The lowest level of the architecture is the services of Web service, Grid service networks. Grid services typically provide job execution, large scale file storage and brokering services in a secured way, while Web services make pre-defined computational algorithms accessible via SOAP messages. gUSE services connect to this tier to perform computation, data management on behalf of the users.