Distributed Systems and Grid Computing division of the Jülich Supercomputing Centre (JSC) in Germany developed a UNICORE plugin for Taverna. “UNICORE (Uniform Interface to Computing Resources) offers a ready-to-run Grid system and makes distributed computing and data resources available in a seamless and secure way.” The UNICORE plugin for Taverna enables users to submit jobs from Taverna Workbench to any UNICORE resource.

To get access to UNICORE resources from Taverna, the user registers a new UNICORE registry in Taverna’s Service Panel. This UNICORE registry is then queried and the UNICORE services orchestrator returns a list of available applications. The applications are selected from various UNICORE resources, as each installation holds a file that describes the available applications, including metadata on the specific resource.

The list of applications is then used in Taverna to display available UNICORE services (applications), which can be added as services to Taverna workflows. The metadata is used to create input and output ports of the specific application/service. Users can than connect inputs/outputs to other workflow services in the usual manner.

During the worfklow execution, a job description is created and submitted to the UNICORE service orchestrator(SO). Files are being uploaded and stored under a logical filename. The SO then manages the execution and file
transmission. The status of the submitted job is polled in the background from Taverna. After the job finished, some files are downloaded, and for further modification, only the logical file name is retrieved.

Additionally, the UNICORE services are using Taverna’s Credential Manager to get access to the user’s X.509 certificate, which user has to load prior to service invocation, along with the other CA’s certificates. The UNICORE services then access the user’s certificate and use it for job submission (since UNICORE’s security concept is based upon grid security and X.509 certificates).

A snapshot of the plugin in Taverna is below.