Trigger objects monitor event triggers that plug-ins define. For example, the vCenter Server plug-in defines these events as Task objects. When the task ends, the trigger sends a message to a waiting trigger-based long-running workflow element, to restart the workflow.
The time-consuming event for which a trigger-based long-running workflow waits must return a VC:Task object. For example, the startVM action to start a virtual machine returns a VC:Task object, so that subsequent elements in a workflow can monitor its progress. A trigger-based long-running workflow's trigger event requires this VC:Task object as an input parameter.
You create a Trigger object in a JavaScript function in a Scriptable Task element. This Scriptable Task element can be part of the trigger-based long-running workflow that waits for the trigger event. Alternatively, it can be part of a different workflow that provides input parameters to the trigger-based long-running workflow. The trigger function must implement the createEndOfTaskTrigger() method from the Orchestrator API.
Important
You must define a timeout period for all triggers, otherwise the workflow can wait indefinitely.
Prerequisites
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Create a workflow.
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Open the workflow for editing in the workflow editor.
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Add some elements to the workflow schema.
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In the workflow, declare a VC:Task object as an attribute or input parameter, such as a VC:Task object from a workflow or workflow element that starts or clones a virtual machine.
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Procedure
1 | Drag a Scriptable Task element from the Generic menu into the schema of a workflow. |
2 | Link the Scriptable Task element to the elements that precede and follow it in the workflow schema.
One of the elements that precedes the Scriptable Task must generate a VC:Task object as its output parameter.
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3 | Click the Scriptable Task element to show its properties tabs in the bottom half of the Schema tab. |
4 | Provide a name and description for the trigger in Info properties tab. |
5 | Click the IN properties tab. |
6 | Right-click in the IN tab and select Bind to workflow parameter/attribute.
The input parameter selection dialog box opens.
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7 | Select or create an input parameter of the type VC:Task.
This VC:Task object represents the time-consuming event that another workflow or element launches.
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8 | (Optional) Select or create an input parameter of the Number type to define a timeout period in seconds. |
9 | Click the OUT properties tab. |
10 | Right-click in the OUT tab and select Bind to workflow parameter/attribute.
The output parameter selection dialog box opens.
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11 | Create an output parameter with the following properties.
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Create the Name property with the value trigger.
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Create the Type property with the value Trigger.
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Click Create ATTRIBUTE with same name to create the attribute.
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Leave the value as Not set.
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12 | Define any exception behavior in the Exceptions properties tab. |
13 | Define a function to generate a Trigger object in the Scripting tab.
For example, you could create a Trigger object by implementing the following JavaScript function.
trigger = task.createEndOfTaskTrigger(timeout);
The createEndOfTaskTrigger() method returns a Trigger object that monitors a VC:Task object named task.
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14 | Click Save at the bottom of the workflow editor. |
You defined a workflow element that creates a trigger event for a trigger-based long-running workflow. The trigger element generates a Trigger object as its output parameter, to which a Waiting Event element can bind.
What to do next
You must bind this trigger event to a Waiting Event element in a trigger-based long-running workflow.