Workflow CapabilitiesThe HELIO Research Infrastructure has been developed as a set of services that can be used independently or orchestrated using scripting languages or workflow tools. Each of the services has a specific functionality, but in combination they are greater than the sum of the parts.
The HELIO services have Web Services interfaces that are described by WSDLs and can be therefore executed within a Taverna workflow. Taverna is an open source workflow system that is actively developed and supported by the myGrid team; it is closely integrated with other myGrid products, including myExperiment.
There are two Taverna products – which is most suitable depends on the type of usage:
- The Taverna Workbench is an application that runs on the user's desktop and is used to create workflows in a graphical user interface environment. The Workbench is a Java based development and runs on all operating systems within a Java Virtual Machine. [Figure: Taverna Workbench]
- The Taverna Server is for executing workflows remotely. The Server was developed during the HELIO project – it makes it possible to create and run workflows that combine HELIO services and hide this from the user.
The workflows created for the HELIO project are stored in the myExperiment repository under a group called "helio". Using the myExperiment repository allows the project to share its workflows and other files with the science community.
Note that while some workflows created for the project are available for download by any user, others are shared only for members of this group. If you are thinking of building workflows for the Heliophysics domain, and want to share your work with other scientists, please consider joining the "helio" group.
|Figure: Example of a simple workflow searching the GOES Soft X-ray flare list in the Heliophysics Event Catalogue (HEC).|
HELIO has been implemented with multiple instances of its services – this is designed to provide system resilience and facilitate load balancing. In order to be able to make use of this capability within Taverna a plug-in has been developed for HELIO that uses the Registry to resolve the URL that should be used to address a particular service.
Useful InformationWe have prepared the following Tutorial to help users: Taverna Workshop was held for HELIO Users at the University of Manchester; the the following handouts were provided:
Link to the HELIO workflows stored under myExperiment.
Last updated: 21st April 2015