code: public Subject login(String userName, String password) throws MessagingAuthenticationException {
  		if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) {
  			SibTr.entry(tc, CLASS_NAME + "login", new Object[] { userName,
  					"Password Not Traced" });
  		}
  		Subject result = null;
  		if (!runtimeSecurityService.isMessagingSecure()) {
  			result = runtimeSecurityService.createUnauthenticatedSubject();
  		} else {
  			if (messagingAuthenticationService != null) {
  				result = messagingAuthenticationService.login(userName,
  						password);
  			}
  		}
  		if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) {
  			SibTr.exit(tc, CLASS_NAME + "login", result);
  		}
  		return result;
  	}
docs: Login method to authenticate a user based on UserName and Password sent
  <ul>
  <li>If Security is enabled, it calls the MessagingAuthenticationService
  for authenticating</li>
  <li>If Security is disabled, it returns an Unauthenticated Subject</li>
  </ul>
  
  @param userName
  UserName of the User
  @param password
  Password for the User
  @return subject - If User is authenticated null - If User is
  unauthenticated