ADF page with optional login using mod_osso authentication

Question

Using JDeveloper 10.1.3.2.0
I am converting a pure jsp page into an ADF page. This page is not restricted but allows a user additional funtionality if they log into Portal. The original jsp used mod_osso authentication to allow a user to log in. Once the user's name was known from the login then the screen could save information specific to a user and if the user had to return later all they had to do was login in once again to get their personal information back. However it was not a requirement for any user to use this functionality.
In converting to ADF however I can't figure out how to code the mod_osso call successfully. I created a command button and behind the button but the following code:
public String commandButton_action() throws IOException {
// Add event code here...
String userName = getUserSSO();
userLoginName.setValue(userName);
return null;
private String getUserSSO() throws IOException {
String message = "";
FacesContext fc = FacesContext.getCurrentInstance();
((HttpServletResponse) FacesContext.getCurrentInstance().getExternalContext().getResponse()).setContentType("text/html");
String userSignon = (String)((HttpServletRequest) FacesContext.getCurrentInstance().getExternalContext().getRequest()).getAttribute("USER_NAME");
if(userSignon == null || userSignon.length() <= 0)
userSignon = ((HttpServletRequest) FacesContext.getCurrentInstance().getExternalContext().getRequest()).getRemoteUser();
if(userSignon == null || userSignon.length() <= 0)
((HttpServletResponse) FacesContext.getCurrentInstance().getExternalContext().getResponse()).setHeader("Osso-Paranoid", "false");
((HttpServletResponse) FacesContext.getCurrentInstance().getExternalContext().getResponse()).sendError(499, "Oracle SSO");
} else
message = "found user name " + userSignon;
return message;
Could please comment on whether I am even on the right track or point me to some documentation on mod_osso authentication and ADF such that the authentication is optional? Currenlty I get "No Response from Web Application Server" when I attempt the above.
Thanks,
Cathy

Answer 1

I added a call to FacesContext.getCurrentInstance().responseComplete(); right before the setHeader and sendError but that did not resolve my issue. Any advice on how to further trace down the issue?
Thanks,
Cathy