How many messages are sent across the network for processing topic messages?

If there are three subscribers for a message, for example, one of which with a selector that does not match, how many messages are sent?

In WebLogic JMS 6.1, when all three consumers are in the same session, we send one copy of the message across the network for all subscribers that are not flow-controlled. Once a consumer is flow-controlled for not acknowledging enough messages, no messages are sent until flow control is eased. So, the answer is usually one, but may be two. The selection is done on the server side so a subscriber that doesn't match doesn't have to discard anything.