For each type of subscription you must define a class that implements a listener for events that can be raised on the subscription type. For example, events relating to record subscriptions (IRecordSubscription) are handled by an implementation of IRecordSubscriptionListener. The various subscription listeners all inherit from ISubscriptionListener, so they must implement the callback methods defined here.

Note: StreamLink queues events in the order they were raised and passes each event in turn to an appropriate callback method of the relevant listener. All listener callbacks execute in the same dedicated worker thread, so while a particular callback method is running no other callbacks will be invoked.