Notification API Overview
The Notification API allows your application to send notifications to users of a front-end trading application.
With the API, your application can open a unique channel of communication for each user, send that user notifications with arbitrary fields and allow the user to respond with actions for each notification received. Examples of notifications you may want to send include system level notifications, such as a service going down or trade life-cycle events, such as order fills.
The StreamLink Alerts API provides a means of integrating with
with the Notification API. It allows a user to subscribe to their
NotifcationChannel, prompting a call into the
with the Notification API's representation of that channel. The
StreamLink Alerts API can be used to send the preconfigured action,
'DISMISS', or any other custom action.
The 'DISMISS' action is the only action to have automatic behaviour associated with it. When a 'DISMISS' is sent by the StreamLink Alerts API, the notification in question will be removed from the cache, and that user will be unsubscribed from that Notification.Under the hood, a NotificationChannel is a container on the subject /PRIVATE/NOTIFICATIONS/%u/CONTAINER. The channel is populated with Notification records identified by sourceName and user provided unique id. The NotificationProvider allows multiple NotificationChannels, each associated with a user, to be serviced on a single namespace.
Source Name - identifies the NotificationProvider in logs and over jmx. Passed into constructor of NotificationConfiguration. NotificationChannel - corresponds to a set of notifications for a single user. Notifications are added to and removed from this. Notification - a notification with arbitrary fields sent to the user subscribed to the NotificationChannel
Instantiating a NotificationProviderHere is how you would instantiate a NotificationProvider given a NotificationApplicationListener called NotificationGenerator:
public class InstantiatingANotificationProvider implements ConnectionListener
private final Logger logger;
public InstantiatingANotificationProvider(DataSource dataSource)
this.logger = dataSource.getLogger();
NotificationConfiguration configuration = new NotificationConfiguration("NotificationProviderId");
new NotificationProvider(dataSource, configuration, new NotificationGenerator(logger));
public void onPeerStatus(PeerStatusEvent peerStatusEvent)
logger.info("onPeerStatus: " + peerStatusEvent);
public static void main(String args) throws Exception
// Example arguments: -f ./Blade/DataSource/etc/datasource.conf --config-base-location=global_config
DataSource dataSource = DataSource.fromArgs(args);
// The DataSource should not be started before creating a NotificationProvider to ensure all notification requests are received
Sample ApplicationListenerHere is the example ApplicationListener, NotificationGenerator:
public class NotificationGenerator implements NotificationApplicationListener
private final SimpleDateFormat DATE_FORMAT = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss Z");
private final Logger logger;
private int currentMessageIndex = 0;
public NotificationGenerator(Logger logger)
this.logger = logger;
public void notificationChannelOpened(NotificationChannel channel)
// References to channels are obtained here. A reference
// would usually be kept so that notifications can be added and
// removed with sendNNotification(s) and removeNotification(s)
// as and when.
logger.info("notificationChannelOpened: " + channel.getSubject());
private Notification notificationFor(String username)
//fields used here must be in your fields.conf
Notification notification = new Notification(Integer.toString(++currentMessageIndex));
notification.setField("tradeDate", DATE_FORMAT.format(new Date()));
public void notificationChannelClosed(NotificationChannel channel)
//any channel cleanup should go here
logger.info("notificationChannelClosed: " + channel.getSubject());
This package contains the public elements of the Notification API.