WDCS Introduction¶
The HUMBOLDT Workflow Design and Construction Service consists of two sub-systems, a graphical user interface, called the Workflow Editor, allowing users to compose geoprocessing components into workflows. Second, a web service, called the Workflow Repository Service, that accepts requests for workflows and delivers them to clients (in HUMBOLDT, the Mediator Service).
The Workflow Editor¶
The Graphical User Interface of the WDCS, called the Workflow Editor, can be used by users to register processing components and to specify chains / compositions of such components (i.e. workflows). The GUI offers therefore quite a similar functionality as e.g. the GUI of the ArcGIS Model Builder or a BPEL Workflow Designer but additionally provides assistance to the user in the composition process by e.g. comparing the input/output type definitions of the components to be connected. For example, this prevents users from connecting components processing raster data with processing component accepting vector data and hence reduces the risk of runtime errors when executing the composition. Currently, the processes to be composed can either be exposed as OGC WPS Processes or directly implemented in java and accessible to the HUMBOLDT Mediator Service.
The Workflow Editor acts as a client application to the Workflow Repository and allows users to deploy the workflows such that they will be subsequently offered via the web service interface of the Workflow Service (see next section).
More information on the Workflow Editor can be found here: Workflow Frontend. The technical documentation for developers can be found here Technical Documentation. Installabe version for windows (32 and 64 bit), linux and maxOS can be found here: Workflow Editor Downloads
The Workflow Repository Service¶
Further, the WDCS offers a web service interface (WSDL) to clients (in HUMBOLDT, the Mediator Service, but could be any workflow execution service). Via this interface, it accepts a number of SOAP requests:
- getWorkflowOfferings: This operation delivers information on the workflows currently availabe via that service.
- getWorkflow: Given a workflow identifier, this operation returns an executable workflow in the HUMBOLDT workflow XML-dialect.
- deployWorkflow: Allows client applications (in HUMBOLDT, the workflow editor) to deploy executable workflows.
More information on the Workflow Repsitory Service can be found here Workflow Service.
A running prototype of the workflow service is accessible here: http://staging-esdi-humboldt.igd.fraunhofer.de:8008/wdcs?wsdl
12.08.2010: The Workflow Repository Service is currently down. The new release of the Workflow Editor contains exeuction functionality and therefore makes the repository service obsolte for the current status.