Re: Call REST service from GWT App's client side

Access-Control-Allow-Origin is a response header, to be sent from the server. See http://www.w3.org/TR/cors/

Note that this rules out quite a few users though: http://caniuse.com/cors (note: GWT won't use XDomainRequest)

If you need to support IE8/IE9, then use deferred-binding and JSNI to use XDomainRequest in those browsers; or use another technique that works across browsers:

• JSON-P with JsonpRequestBuilder (for GETs only),
• using a "proxy" on the same origin as your GWT app : https://code.google.com/p/google-web-toolkit/issues/detail?id=3131#c25
  
• or run your GWT app from the same origin as your service (that might be useful: http://www.gwtproject.org/doc/latest/DevGuideCompilingAndDebugging.html#How_do_I_use_my_own_server_in_development_mode_instead_of_GWT's)

On Wednesday, September 4, 2013 11:50:12 PM UTC+2, SergeZ wrote:

Hi everyone! Please, help me figure out how can I manage to call the external REST service from GWT application's client code.

I've heard, that GWT has a RequstBuilder class in order to do such things, but suddenly I figured out that this is a quite ancient approach to implement. Hence, the following code won't work:

RequestBuilder builder = new RequestBuilder(RequestBuilder.GET, "http://localhost:19999/hello");

        builder.setHeader("content-type", "text/html;charset=windows-1251");

        builder.setHeader("Access-Control-Allow-Origin", "*");//result doesn not depend on this line of code

        try {

            Request response = builder.sendRequest("", new RequestCallback() {

                @Override

                public void onResponseReceived(Request request, Response response) {

                    answerFromRest.setText(request.toString() + "\n");

                    answerFromRest.setText(response.toString() + "\n");

                    int statusCode = response.getStatusCode();

                    if(statusCode == Response.SC_OK) {

                        String responseBody = response.getText();

                        answerFromRest.setText("The result is " + responseBody);

                    } else {

                        answerFromRest.setText("There was an error " + statusCode + " =" + response.getText());

                    }

                }

                @Override

                public void onError(Request request, Throwable exception) {

                    //error actually sending the request, never got sent

                }

            });

        } catch (RequestException e) {

            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.

        }

statusCode always equals 0 though when I access my depolyed REST through a WebBrowser, I get the result. This makes me feel like there is really no more support for that code in GWT...

So, the question is - is there the other (working) way to call REST writing code in java ( I mean w/o using JSNI code to do that ).

Any way, whatever approach is ( if it exists in GWT's nowadays ), can you please provide either _code_ or _decent link with tutor or smth like that_ ?

Thank you very much, for the time spent on my subject!!!!

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