title: In which domains are message oriented middleware like AMQP useful?
body: <p>What problem do MOM (Message Oriented Middleware) solve? Scalability? Integration?</p>
  
  <p>In which domain are they typically used and in which domains are they typically <em>not</em> used?</p>
  
  <p>For example, say, is Google using such solution for it's main search engine or to power GMail?</p>
  
  <p>What about big websites like Walmart, eBay, FedEx (pretty much a Java shop) and buy.com (pretty much an MS shop)? Does MOM solve a need there?</p>
  
  <p>Does it make any sense when you're writing a Webapp where you control the server-side and have an homogenous environment (say tens of Amazon EC2 instances all running Linux + Java JVMs) there and where the clients are, well, Web browsers?</p>
  
  <p>Does it make sense for desktop apps that need to communicate with a server?</p>
  
  <p>Or is it 'only' for big enterprise stuff where you typically have a happy mix of countless of different systems that needs to communicate in a way or another?  </p>
  
  <p>I'm a bit confused as to what they're useful for and I think that with example of where they're appropriate and where they're not appropriate I could better understand their use.</p>