WS-PGRADE

The WS-PGRADE Portal (Web Services Parallel Grid Runtime and Developer Environment Portal) is the Liferay-based web portal (WS-PGRADE web application) of gUSE, wich also includes a graphical portal service. WS-PGRADE is a Web portal hosted in a standard portal framework, using the client APIs of gUSE services to turn user requests into sequences of gUSE specific Web service calls. WS-PGRADE hides the communication protocols and sequences behind JSR286 compliant 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. The members of gUSE community can access WS-PGRADE via ordinary web browsers. Application developers can access to all the advanced workflow features (graph, abstract workflow, template, application and project) to develop new workflow applications and upload them to the gUSE repository. For scientific end-users WS-PGRADE gives full access to the parameterization and execution of applications downloaded from the gUSE repository.

The WS-PGRADE Workflow

The workflow is a configured graph of jobs i.e. it is an extension of the graph with attributes, where the configuration is grouped by jobs. The properties of jobs reflect the elaboration of the enclosing workflow. The job configuration includes:

  • algorithm configuration: determines the functionality of a job
  • resource configuration: determines where this activity will be executed
  • port configuration: determines what input data of the activity are and how the result(s) will be forwarded to the user or to other jobs as inputs.

A job may be executed if there is a proper data at each of its input ports and there is no prohibiting programmed condition excluding the execution of the job. The collection of job instances created from the jobs belonging to the workflow during a single workflow submission is called workflow instance.

The Embedded Workflow

Another important feature of the WS-PGRADE workflows is the support for embedding workflows. This enables the usage of the “subroutine paradigm”, i.e., a tested workflow B can be used inside a parent workflow A by specifying that the executable of a certain node in A should be workflow B.

The PS features

By gUSE you can run your PS application in various DCIs without changing the application workflow. What is PS application? The PS (Parameter Sweep, Parameter Set or Parameter Study) applications are typically simulations where the same simulation application should be executed with many different input sets. DCIs are ideal for PS executions and therefore their most frequent usage scenario is performing such parameter sweep applications. This implies that any good science gateway should provide an easy-to-use way of support to construct and execute parameter sweep applications.

Certificates

The gUSE/WS-PGRADE users are identified and authorized to use resources of grid by X.509 certificates. Within the EGI infrastructure the resources of a given VO (Virtual Organization) are restricted for the members. The personal certificate is an unavoidable condition to obtain a VO membership. A user may be the member of more than one VO in one time.

For safety reason, the jobs are not submitted to a resource in the company of a long term user certificate (which has a one year long validity expiration), but by using a substituting short term, so called proxy certificate (with a validity expiration time, limited in 100 hours), which is issued by a secure - so called MyProxy - server playing the role of a certificate authority, against the submission of the long term user certificate.