CODEWITHSUNDEEP
helix
Jaraws
Jaraws

Reputation: 691

How to send a message from Helix controller to participant?

I want to send a message to all Participant nodes of my Helix cluster from Controller node. I tried following piece of code to send message to all registered participants of my cluster but their registered Participant message listeners are not receiving the message notification from Helix.

Message msg = new Message(factory.getMessageTypes().get(0), msgId);
msg.setMsgId(msgId);
msg.setSrcName(hostSrc);
msg.setTgtSessionId("*");
msg.setMsgState(MessageState.NEW);
msg.getRecord().setSimpleField("TestMessage", "Message from controller");

Criteria recipientCriteria = new Criteria();
recipientCriteria.setRecipientInstanceType(InstanceType.PARTICIPANT);
recipientCriteria.setInstanceName("%"); // To all recipients 
recipientCriteria.setSessionSpecific(true);    // To deliver only live participants
recipientCriteria.setSessionSpecific("DEV_CLUSTER"); // To only participants of this cluster

messagingService.send(recipientCriteria,msg);

Note that, when I am sending this message there is no resource exists in the cluster.

After debugging further what I have observed is CriteriaEvaluator.evaluateCriteria(....) operation is returning an empty list which further results into 0 messages to be sent to Participants nodes.

Kindly let me know if I am missing anything here while defining my criteria for Participants.

Thanks !

Update-1: our observation on this issue is as follows:

  1. The received message at the participant side is read by both the Participant message listener(Say L1) and the handler created through MessageHandlerFactory(Which internally creating a listener HelixtaskExecutor (Say L2)).

  2. In case if the message is read by HelixTaskExecutor(L2) first, it then immediately deletes the Znode in Zookeeper and the additionally configured message listener(L1) doesn't receive this message.

  3. In case if the message is first read my additional message listener i.e. L1 then in such scenarios we don't face this problem as this additionally added listener doesn't delete the Znode from ZooKeeper.

We are still not sure how can we handle this problem as we want to use both the listener and MessageHandlers but facing the same problem I stated above.

Any inputs are appreciated.

Upvotes: 1

Views: 82

Answers (0)

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