Why can't we get access to HttpSession object from an EJB based JAXWS endpoint

[Dhriti lanka]

When Both Servlet based and EJB based services have access to the MessageContext Object,
Why can't we get the access the HTTPSession object from an EJB based service using:

MessageContext.getRequest(MESSAGECONTEXT.SERVLET_REQUEST).getSession();

Can someone throw some light?

[Lester Burnham]

Why would an EJB (or its WS endpoint) have an HTTP session?