Possible causes

  • After the consumer and producer are created, the start() method is not called to start the client.
  • After the consumer and producer are created, startup of the client fails due to an exception in the start() process.
  • After the consumer and producer are created, start() is successfully called, but the client is shut down by calling shutdown().

Recommended solution

Perform the following steps:

  1. Check that the start() method is called after the consumer and producer are created. Ensure that the client is started.
  2. Check ons.log for exceptions that occur in the startup process of the client.