...The app also implements an admin panel, through which you can test single and bulk notifications. Select one or more FCM/GCM, APNS, WNS or WebPush devices and in the action dropdown, select "Send test message" or "Send test message in bulk", accordingly. Note that sending a non-bulk test message to more than one device will just iterate over the devices and send multiple single messages. UPDATE_ON_DUPLICATE_REG_ID: Transform create of an existing Device (based on registration id) into an update. Sending messages in bulk makes use of the bulk mechanics offered by GCM and APNS. ...