title: wait with systemd until a service socket becomes available and then start a depended service
body: <p>Currently I have slow starting java service in systemd which takes about 60 seconds until it opens its HTTP port and serves other clients.</p>
  
  <p>Another client service expects this service to be available (is a client of the this service), otherwise it dies after a certain retry. It also started with systemd. This is to be clear also a service. But uses the former like database.</p>
  
  <p>Can I configure systemd to wait until the first service has made his socket available?  (something like if the socket is actually listens , then the second client service should start).</p>