JavaTM Platform, Enterprise Edition (Java EE) s...

The server containers provide runtime support for Java EE application components (such as servlets and Enterprise JavaBeans^TM (EJB^TM)). They provide a layer between application component code and platform services and resources. All application component code is run on a thread managed by a container and each container typically expects all access to container-supplied objects to occur on the same thread.

It is because of this behavior that application components are typically unable to reliably use other Java EE platform services from a thread that is not managed by the container.