When the type attribute is VELOCITY, the value attribute corresponds to the name of the Velocity Template. “Arg” nodes can be used to pass values from the event to the Velocity Template. For example, you could have a velocity template for a DeviceDeleteEvent, (for instance, device_delete.vm), which contains the text Device $deviceName deleted from Network $networkName.

You could pass the values for deviceName and networkName as arguments to this template by defining two “arg” nodes with type = XPATH and value = <the xpath to the deviceName/networkName node>

For Example:

<Transform eventName = "DeviceDeleteEvent">
      <Property name="body" type="VELOCITY" 
<arg key="0" value="/VoyenceEvent/Device/DeviceDeleteEvent/DeviceId/Name"/>
<arg key="1" value="/VoyenceEvent/Device/DeviceDeleteEvent/NetworkId/Name"/>