title: Why stateless session beans are single threaded?
body: <p>As per my understanding stateless session beans are used to code the business logic. They can not store data in their instance variables because their instance is shared by multiple requests. So they seem to be more like Singleton classes. However the difference is contain creates (or reuses from pool) the separate instance of stateless session beans for every request.</p>
  
  <p>After googling I could find the reasoning that the Java EE specification says they are suppose to be single threaded. But I can't get the reason why the are specified to be <strong>SINGLE THREADED</strong>?</p>