1.
Introduction
Up one level
For convenenience in the documentation, we refer to GRIA applications that have been created from workflows as workflow applications. Also, a job created from a workflow application is referred to as a workflow job.
Architecture
The diagram below illustrates that a Taverna workflow ("a Workflow application" in the diagram) can be deployed to the GRIA Job Service as a GRIA application. After deployment, clients can create jobs from a workflow application using the Job Service in exactly the same way as they would for other GRIA applications. Clients will not necessarily be aware that they are using a workflow application, though this may be apparent from log messages that are made available when monitoring job execution. Note that the diagram is conceptual and this section covers only the details relevant to deploying and using workflow applications. For full details on the relationship between applications and the Job Service, refer to the Job Service documentation in the Basic Application Services User Guide.
Architecture
GRIA applications consist of an application directory containing at least an application wrapper script, startJob.pl, and an application description file, ApplicationMetadata.xml. For each GRIA application, a directory should be created to store the application wrapper and application description files. The application wrapper is invoked indirectly from the Job Service when job execution is started. Usually, the application wrapper will invoke a command line executable that provides the functionality for the application.
For workflow applications, there is a single command line executable
(GRIA Workflow Application) that is responsible for executing the
Taverna workflow and mapping input and output data stagers to workflow
inputs and outputs. This is illustrated in the diagram below.
Job Service and GRIA Workflow Application interactions
When a workflow job is started, the Job Service invokes (via a platform script) the startJob.pl application wrapper. In turn, the application wrapper invokes the GRIA Workflow Application (GWA). The GWA compiles the workflow, workflow.xml, and also reads the application description file, ApplicationMetadata.xml. The application description file is used to map input and output data stagers to workflow inputs and outputs. Finally, the GWA executes the workflow and makes workflow outputs available in the output data stagers for the job.
Note that the ApplicationMetadata.xml and startJob.xml can be generated automatically from a workflow file, using the deploy tool. Further details are provided in the tutorial.
Related Components
GRIA documentation and software downloads are available from the GRIA homepage. Taverna information and user documentation can be found at the Taverna project site. The latest releases of the GRIA Workflow Plugins and user documentation can be obtained from the GRIA homepage also.
