Create a custom trigger (Example 3)

The example shows how to create an event-based trigger (SimpleMessageListenerContainer) using the Package SDK.

Event-based triggers - Push mechanism

The trigger waits for an event to occur, for example, a message listener to start listening.

An event details are stored in the memory and a message listener waits for a message.
When the event occurs, it runs the consumer.accept(<RecordValue Instance>) method and triggers an associated bot..

The following example shows how to create a simple ActiveMQ message listener (SimpleMessageListenerContainer) to demonstrate the trigger push mechanism.

@BotCommand(commandType = BotCommand.CommandType.Trigger)
@CommandPkg(label = "JMS Trigger", description = "JMS Trigger", icon = "jms.svg", name = "jmsTrigger",
		return_type = RECORD, return_name = "TriggerData", return_description = "Available keys: triggerType")
public class JMSQueue implements SessionAwareMessageListener {

	// Map storing multiple MessageListenerContainer
	private static final Map<String, MessageListenerContainer> taskMap = new ConcurrentHashMap<>();

	@TriggerId
	private String triggerUid;
	@TriggerConsumer
	private Consumer consumer;
	
	//This method is called by MessageListenerContainer when a message arrives.
	// At this point, the trigger get enabled 
	@Override
	public void onMessage(javax.jms.Message message, Session session) throws JMSException {
		consumer.accept(getRecordValue());

	}

	private RecordValue getRecordValue() {
		List<Schema> schemas = new LinkedList<>();
		List<Value> values = new LinkedList<>();
		schemas.add(new Schema("triggerType"));
		values.add(new StringValue("JMSQueue"));

		RecordValue recordValue = new RecordValue();
		recordValue.set(new Record(schemas,values));
		return recordValue;
	}
	/*
	 * Starts the trigger.
	 * 
	 * Use this method to setup the trigger, such as, setup the MessageListenerContainer and start it.
	 */
	@StartListen
	public void startTrigger(@Idx(index = "1", type = AttributeType.TEXT)
	@Pkg(label = "Provide the broker URL")
	@NotEmpty
	String brokerURL, @Idx(index = "2", type = AttributeType.TEXT)
	@Pkg(label = "Provide the queue name")
	@NotEmpty
	String queueName) {
		
		if (taskMap.get(triggerUid) == null) {
			synchronized (this) {
				if (taskMap.get(triggerUid) == null) {
					SimpleMessageListenerContainer messageListenerContainer = new SimpleMessageListenerContainer();
					messageListenerContainer.setConnectionFactory(new PooledConnectionFactory(brokerURL));
					messageListenerContainer.setDestinationName(queueName);
					messageListenerContainer.setMessageListener(this);
					messageListenerContainer.start();
					taskMap.put(triggerUid, messageListenerContainer);

				}
			}
		}

	}

	/*
	 * Cancel all the tasks and clear the map.
	 */
	@StopAllTriggers
	public void stopAllTriggers() {
		taskMap.forEach((k, v) -> {
			v.stop();
			taskMap.remove(k);
		});
	}

	/*
	 * Cancel the tasks and remove from the map
	 *
	 * @param triggerUid
	 */
	@StopListen
	public void stopListen(String triggerUid) {
		taskMap.get(triggerUid).stop();
		taskMap.remove(triggerUid);
	}

	public String getTriggerUid() {
		return triggerUid;
	}

	public void setTriggerUid(String triggerUid) {
		this.triggerUid = triggerUid;
	}

	public Consumer getConsumer() {
		return consumer;
	}

	public void setConsumer(Consumer consumer) {
		this.consumer = consumer;
	}

}

Automation 360

Create a custom trigger (Example 3)