title: How can you tell when a Kafka Streams app is in the "running" state?
body: <p>Given a recently started Kafka Streams app, how can one reliably determine that it has reached the "RUNNING" state? This is in the context of a test program that launches one or more streams apps and needs to wait until they are running before submitting test messages.</p>
  
  <p>I know about the <code>.setStateListener</code> method but I'm wondering if there is a way of detecting this state from <em>outside</em> the app process. I thought it might be exposed as a jmx metric but I couldn't find one in VisualVM</p>