Re: RequestBuilder returning "empty argument" result?

Could you be running into the SOP (same origin policy) problem? If
your GWT and CGI script are running on different hosts the GET/POST
requests won't work. See:
http://code.google.com/docreader/#p=google-web-toolkit-doc-1-5&s=google-web-toolkit-doc-1-5&t=FAQ_SOP
http://code.google.com/docreader/#p=google-web-toolkit-doc-1-5&s=google-web-toolkit-doc-1-5&t=GettingStartedJSON
(scroll down to the SOP section for potential workarounds).

Hope this helps.

On Nov 9, 7:47 pm, dk <dean.kar...@gmail.com> wrote:
> Hi,
>
> This is about GWT 1.7.1 on a RedHat EL 5.4 system.
>
> I have been messing with GWT for a while now.  I am not an expert and
> am really still a java newbie.  I have the following code snippet
> in an application I am writing.  There is an existing CGI app and
> I am replacing the GUI with GWT and using the existing CGI scripts
> for the data operations.
>
> I am setting up a RequestBuilder call to retrieve data from a CGI
> script.  That script generates data and sends it as a JSON string back
> to this routine.  The issue is that I am receiving an:
>
>     empty argument
>
> message that is generated by the JSONParser.  The message comes
> through the catch clause that holds the
>
>     LOG("getInfo:onResponseReceived:e2:"
>
> line.
>
> I *know* the CGI script is doing its thing.  I can run it from the
> command line and visit its URL and I get JSON'd data that looks OK
> to my eye.  The code section looks like:
>
>     public void getInfo() {
>         RequestBuilder req;
>         LOG("getInfo:a");
>
>         req = new RequestBuilder(RequestBuilder.GET,
>                                  URL.encode(baseURL + "archive.cgi"));
>
>         LOG("getInfo:b:"+req.getUrl());
>
>         try {
>             req.sendRequest(null, new RequestCallback() {
>                 public void onError(Request request, Throwable e) {
>                     Window.alert("getInfo failed: " + e.toString());
>                 }
>
>                 public void onResponseReceived(Request request,
>                                                Response response) {
>                     JSONObject Info;
>                     try {
>                         LOG("getInfo:onResponseReceived:a:");
>                         Info = JSONParser.parse(response.getText()
>                                                            ).isObject
> ();
>                     }
>                     catch (NullPointerException e) {
>                         LOG("getInfo:onResponseReceived:e1:" +
>                              e.getMessage());
>                         throw new RuntimeException(
>                                          "Failed to send JSON
> request");
>                     }
>                     catch(IllegalArgumentException e) {
>                         LOG("getInfo:onResponseReceived:e2:" +
>                             e.getMessage());
>                         throw new RuntimeException(
>                                          "Failed to send JSON
> request");
>                     }
>                     catch(Exception e) {
>                         LOG("getInfo:onResponseReceived:e3:" +
>                             e.getMessage());
>                         throw new RuntimeException(
>                                          "Failed to send JSON
> request");
>                     }
>
> Here is a sample JSON'd string.
>
> {"searchTerm":"","pending":["<h2>Calendar for Fall 2009</h2>
> \n","<h3>Tuesday, November 10, 2009<br/>MRI Stuff</h3>\n<h4>Speaker:
> Andrew <a href=\"mailto:and...@north.com\"><img src=\"/images/email.jpg
> \" alt=\"(email)\"/></a>, Radiology and Biomedical Engineering</h4>
> \n<h4>Time: 12:00PM</h4>\n<h4>Location: Room 5602</h4>\n<h4>Abstract:</
> h4>\n<p>Transcatheter and percutaneous liver-directed approaches are
> widely used for the treatment of ... procedures.</p>\n","<h3>Tuesday,
> November 17, 2009<br/>Title Forthcoming</h3>\n<h4>Speaker: Chas
> Conway</h4>\n<h4>Time: 12:00PM</h4>\n<h4>Location: </h4>
> \n<h4>Abstract:</h4>\n<p>Abstract Forthcoming</p>\n","<h3>Tuesday,
> November 24, 2009\n<br/>No Forum - Thanksgiving Vacation</h3>
> \n","<h3>Tuesday, December 1, 2009<br/>Title Forthcoming</h3>
> \n<h4>Speaker: Yi Lu, Professor</h4>\n<h4>Time: 12:00PM</h4>
> \n<h4>Location: </h4>\n<h4>Abstract:</h4>\n<p>Abstract Forthcoming</p>
> \n","<h3>Tuesday, December 8, 2009<br/>Title Forthcoming</h3>
> \n<h4>Speaker: </h4>\n<h4>Time: 12:00PM</h4>\n<h4>Location: </h4>
> \n<h4>Abstract:</h4>\n\n","<h3>2009-12-09<br/>Fall Semester Ends</h3>
> \n"]}
>
> This was produced from a Perl cgi script using CGI.pm and JSON::XS
>
> FireFox/FireBug shows the request call and the headers but the result
> is missing.
>
> This code is not really different than other working code and the
> CGI is not really all that different either.
>
> I have tried using a POST method and setting
>
>     req.setHeader("Content-Type", "application/x-www-form-
> urlencoded");
>
> though I am not "sending" any data to the script.
>
> I have tried setting
>
>     req.sendRequest(null, new RequestCallback() {
>     req.sendRequest("", new RequestCallback() {
>     req.sendRequest("dummy=value", new RequestCallback() {
>
> and it is still happening.
>
> It must be something very trivial that I am not seeing.  Can you help?

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