Hi,

I used the AuthServlet sample code in my org to test REST API functionality. I able to reach upto Salesforce login page. But when I gave my credential, it throws the following error.

java.lang.IllegalStateException

at org.apache.catalina.connector.ResponseFacade.sendRedirect(

ResponseFacade.java:435)....

doGet method in AuthServlet.java sample code (http://wiki.developerforce.com/page/Getting_Started_with_the_Force.com_REST_API), that I used is,

protected void doGet(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {
  
  String accessToken = (String) request.getSession().getAttribute(
    ACCESS_TOKEN);
  
  if (accessToken == null) {
   String instanceUrl = null;

   if (request.getRequestURI().endsWith("oauth")) {
    // we need to send the user to authorize
    response.sendRedirect(authUrl);
    return;
   } else {
    System.out.println("Auth successful - got callback");

    String code = request.getParameter("code");

    HttpClient httpclient = new HttpClient();

    PostMethod post = new PostMethod(tokenUrl);
    post.addParameter("code", code);
    post.addParameter("grant_type", "authorization_code");
    //post.addParameter("grant_type", "password");
    post.addParameter("client_id", clientId);
    post.addParameter("client_secret", clientSecret);
    post.addParameter("redirect_uri", redirectUri);

    try {
     httpclient.executeMethod(post);

     try {
      JSONObject authResponse = new JSONObject(
        new JSONTokener(new InputStreamReader(
          post.getResponseBodyAsStream())));
      System.out.println("Auth response: "
        + authResponse.toString(2));

      accessToken = authResponse.getString("access_token");
      instanceUrl = authResponse.getString("instance_url");

      System.out.println("Got access token: " + accessToken);
     } catch (JSONException e) {
      e.printStackTrace();
      throw new ServletException(e);
     }
    } finally {
     post.releaseConnection();
    }
   }

   // Set a session attribute so that other servlets can get the access
   // token
   request.getSession().setAttribute(ACCESS_TOKEN, accessToken);

   // We also get the instance URL from the OAuth response, so set it
   // in the session too
   request.getSession().setAttribute(INSTANCE_URL, instanceUrl);
  }
  response.sendRedirect(request.getContextPath() + "/DemoREST");
 }

I read some where like, response is already commited for the request and hence it throws the error. Can anyone help me, how to call our servlet once the credentials provided in the Salesforce login page.