Use the APIs in the PubSubUtils class to publish and subscribe to events.

• cleanContextSubscribers(contextName)

  Deletes the subscription items of all events under the given context.

• publish(eventType, payload)

  Invokes all items subscribed to a specific type of event and passes the specified payload to the subscribed items.

• subscribe(eventType, subscriptionItem, subscriptionItemName, subscribeOnce, contextName)

  Notifies a subscription item whenever an event occurs in a specific context.

• subscribeOnce(eventType, subscriptionItem, subscriptionItemName)

  Notifies the subscription item only once when a specific type of event occurs.

• unsubscribe(eventType, subscriptionItemName, contextName)

  Unsubscribes a subscription item belonging to a specific type of event.