title: Lightweight Message Bus library
body: <p>I will be starting a small Java (GWT really) project in the near future and I am at "information gathering" phase.</p>
  
  <p>Q: Is there a lightweight Message Bus library written in Java? </p>
  
  <p>My requirements are lightweight too :-)</p>
  
  <ol>
  <li>async (no need for sync)</li>
  <li>multicast and point-to-point</li>
  <li>no strict message ordering</li>
  <li>message "envelope" ideally "owned" by Message Bus (i.e. in terms of life-cycle management)</li>
  <li>localized delivery (i.e. not inter-process nor inter-node)</li>
  </ol>
  
  <p><strong>Update</strong>: It seems that GWT now supports an integrated <a href="http://code.google.com/webtoolkit/doc/latest/tutorial/mvp-architecture.html" rel="noreferrer">"event bus"</a>.</p>