I have a web application that publishes messages to a topic then several Windows services that subscribe to those topics, some with multiple instances. If the services are running when the messages are published everything works correctly but if they are not then the messages are retained on the queue(s) subscribing to that topic but aren't read when the services start back up.

The desired behavior-

1. When a message is published to the topic string MyTopic, it is read from the MyTopicQueue only once. I use some wildcard topics so each message is sent to multiple queues, but multiple instances of a services subscribe to the same topic string and each message should be read by only of those instances

2. If the subscribers to the MyTopic topic aren't online when the message is published then the messages are retained on MyTopicQueue.

3. When the Windows services subscribing to a particularly topic come back on line each retained message is read from MyTopicQueue by only a single subscriber.

I've found some [typically for IBM] spotty documentation about the MQSUBRQ and MQSO_PUBLICATIONS_ON_REQUEST options but I'm not sure how I should set them. Can someone please help figure out what I need to do to get my desired behavior? [Other than switching back to RabbitMQ which I can't do though I'd prefer it.]

My options:

private readonly int _openOptions = MQC.MQSO_CREATE | MQC.MQSO_FAIL_IF_QUIESCING | MQC.MQSO_MANAGED;
private readonly MQGetMessageOptions _messageOptions = new MQGetMessageOptions()

Code to open the Topic:

_topic = _queueManager.AccessTopic(_settings.TopicString, null, 
                    MQC.MQTOPIC_OPEN_AS_SUBSCRIPTION, _openOptions);

The line of code that reads from the topic (taken from a loop):

  _topic.Get(mqMessage, _messageOptions);