How do I receive messages from an Artemis multicast queue in C#?

Question

I'm up to send and receive messages over ActiveMQ Artemis with C# applications. In Anycast-mode, everything is working.

When i tried to send and receive in multicast-mode, i can send, but i don't receive any of the messages from the queue.

I tried the trick from java, set the "multicast" flag before the tcp uri, but an error message shows up that there isn't an implementation for "multicast"

private void Receiver()
{
    IConnectionFactory factory = new NMSConnectionFactory("multicast:tcp://172.29.213.150:61616");
    IConnection connection = factory.CreateConnection("artemis", "simetraehcapa");
    connection.Start();
    ISession session = connection.CreateSession(AcknowledgementMode.AutoAcknowledge);
    IDestination destination = SessionUtil.GetDestination(session, "hund");
    IMessageConsumer receiver = session.CreateConsumer(destination);
    receiver.Listener += new MessageListener(Message_Listener);
}

Normally I would receive the messages, because I only switched from anycast to multicast, but actually I receive nothing.

removing "tcp" didn't help me out here. Gave me the same error as before "no implements for multiast" — FatalErrorEveryday, May 31 '19 at 08:41
At what point do you create your consumer? Is it before or after you send the message? — Justin Bertram, May 31 '19 at 12:17
i create a consumer after sending messages because i want to get the whole queue in one down when i start the consumer — FatalErrorEveryday, Jun 03 '19 at 06:18
As Tim noted in his answer, you can't send messages and then subscribe. That's not the way topics work. The subscription has to exist *before* messages are sent in order to actually receive the messages. — Justin Bertram, Jun 03 '19 at 12:01

score 0 · Accepted Answer · answered Jun 01 '19 at 18:19

If using the AcitveMQ OpenWire NMS client you don't apply that odd multicast thing you've done to the URI, that will give you an error. The client should just work if you use the Session API and not that confusing SessionUtil API that has resulted in many people running into issues.

I'd use Session.CreateTopic to get an ITopic instance and then create a consumer using that which should map over into Artemis Multicast addresses without you needing to do anything. You do of course need to be subscribed before any messages are sent as Topics don't retain messages if no consumers are around when the are sent.

How do I receive messages from an Artemis multicast queue in C#?

1 Answers1