public void requestSuggestions(final Request request, final Callback callback) {
        RequestBuilder requestBuilder = new RequestBuilder(RequestBuilder.GET,"/app/autocomplete/dictionary.json?prefix="+prefix);
        requestBuilder.setHeader("Content-Type", "application/json");

        try {
            requestBuilder.sendRequest(null, new JSONRequestCallback(){

                @Override
                protected void onResponse(JSONValue jsonValue) {
                    final Collection collection = new ArrayList();
                    final Response response = new Response();

                    JSONArray jArr = jsonValue.isArray();
                    for (int i=0;i<jArr.size();i++){
                        collection.add(jArr.get(i).toString());
                    }
                    response.setSuggestions(collection);
                    callback.onSuggestionsReady(request,response);
                }

                @Override
                protected void onForbiddenResponse(JSONValue jsonValue) {
                    Window.alert("Forbidden");
                }
            });
        } catch (RequestException ex) {

        }
    }