This plugin integrates with the Girder worker and allows items in Girder's data hierarchy to act as task specifications for the worker. In order to be used as a task specification, an item must expose two special metadata fields:

• isItemTask must be set to indicate that this is an item task. The key must exist, but the value does not matter.
• itemTaskSpec must be set to a JSON object representing the worker task specification. Documentation of valid worker task specifications can be found in the Girder worker documentation.

In order for users to run this task, they must be granted a special access flag granted on the containing folder, namely the Execute analyses flag exposed by this plugin. This special access flag can only be enabled by site administrators since the capabilities of items as tasks essentially enable arbitrary code execution on the worker nodes. Because of this power, administrators should be very careful of who has write access on folders where this permission flag is granted. It is strongly recommended for security reasons to isolate item tasks in folders separate from normal data, with minimal access granted to non-administrator users.

Once a user has this special access flag on item tasks, they will see the tasks appear in the list of available tasks when navigating to the Tasks view via the nav bar. They can also navigate to the item itself and use the Run this task option from the Actions menu. When they do so, they are prompted with an automatically-generated user interface allowing them to enter inputs to the task and output destinations, and then execute the task on the worker. The progress, status, and log output of the task is tracked in real-time via the jobs plugin. The input and output data for each execution of a task will also appear in that job details view, including links to any Girder data that was used as inputs or outputs.

Many item tasks represent algorithms contained in docker images. Such docker images that implement self-describing behavior can be used to automatically populate an item task's metadata fields. To auto-populate the task spec, navigate to an existing item that will be the item task, open the Actions menu, and select Configure task. A dialog will appear prompting the administrator to enter the docker image identifier and also specify any additional arguments needed to get the description output.

Clicking Run will start a job on the worker to read the image's description. The container is expected to write the description to standard output as a Slicer Execution Model XML document. When the job is finished, the task item specification should be set, and users should now be able to run the task represented by the docker image.