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I was trying to send a notification to the user after he has succesfully done an action, using:

NotificationEvent notificationEvent = NotificationEventFactoryUtil.createNotificationEvent(System.currentTimeMillis(), "com_liferay_document_library_web_portlet_DLPortlet", notificationEventJSONObject);
notificationEvent.setDeliveryType(10002);
List<User> allUsers = UserLocalServiceUtil.getUsers(QueryUtil.ALL_POS,QueryUtil.ALL_POS);
try {
    for (User u : allUsers) {
        UserNotificationEventLocalServiceUtil.addUserNotificationEvent(u.getUserId(), notificationEvent);
    }
} catch (PortalException e) {
    logger.error("Error occured during sending the portal notification to user", e);
}

This works as expected, however this notifications pop up in the receiver user after doing a request (eg, refrteshing the page). Is there a better way to inform users of something in Liferay without the need of them to refresh the page like a sort of push from server to the websocket?

PD: Moreoever I was wondering where can I consult the different available delivery types for the notification events.

Thank you very much in advance!