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Scheduled Events

There are known limitations and caveats with this feature, including unexpected behavior with shared image session data. See Limitations And Caveats below.

New in XNAT 1.8.5 is functionality that allows system administrators to schedule timed execution of automated actions using the XNAT Event Service

How to Subscribe to a Scheduled Event.

As a user with administrator privileges, browse to the Administrator -> Event Service page and select the Add New Event Subscription button.

In the Create Event Subscription dialog, use the Select Event dropdown and select Scheduled Event – Cron option.

This will reveal additional subscription options specific to Scheduled Events. 

Cron Trigger - A Cron Expression that defines when this event will trigger.  (e.g. 0 50 12 * * *) 

Cron Description - A human readable description of the cron trigger.  (e.g. 12:50pm everyday)

Once you've filled out the cron trigger and description, enable and save the event subscription.  Your new Scheduled Event will now fire at the interval you specified in the cron trigger. 

In the example below, the debug-session command will run on all sessions in all projects at 12:50pm everyday. 

Limitations and Caveats

Scheduled Events Must Be Performed By The Subscription Owner

In an event subscription that reacts to an event triggered by a user, the resulting action can be associated with the user who triggered the event using the "Perform Action As" setting. In a scheduled event, there is no external user trigger, so any action triggered by a scheduled event is associated with the user who created the event subscription.

Running Scheduled Container Service Events on Shared Image Session Data can lead to Undesired Behavior

Because the Container Service has limited support for accessing shared experiment resources, scheduling a container execution based on a shared image session can lead to unexpected outcomes.

As background: If an image session is shared from a SOURCE project into a DESTINATION project, only the metadata is duplicated in both projects. The scan resource data is only stored once, in the SOURCE project archive. A container launched from the DESTINATION project will try to mount the SOURCE project's archive

Container Service 

If the subscription's action is a container service command, the command must have an external input that is supported by Scheduled Events.  Inputs that are currently supported are Project, Project Asset, Subject, Subject Assessor, Session, and Assessor.  Commands that don't have a supported external input will not be processed by the subscription. 

Project Level Scheduled Events

Scheduled Events are not currently supported on the project level (Project Report > Actions Box > Event Service).  This means that project owners are not currently able to schedule events for their projects.  Events can still be scheduled for individual projects, but a system administer will need to create the subscription from the Administer > Event Service page.

Cron Trigger Restrictions

Wildcards(*), ranges(-), step values(/), and lists(,) are not supported in the Subscription's Cron Trigger minutes or seconds fields.

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