The guess is that the swing application sends a JSESSIONID cookie in te request or that http client your are using is doesn't do HTTP 1.1.
Actually, i have tried using the applicaton with WebSphere App server and it works.
But while using WebSphere App server, i have used the struts framework. I have extended the ActionServlet provide by struts & the request is processed by this servlet.
So it required that my servlet extend the default servlet provided by Tomcat.