Adam, I've wrote a very quick tutorial on GWT and JSONP with a J2EE container.
Hope you dont mind I've mentioned you and thanked you for the help. Its located at: http://eggsylife.blogspot.com/2008/10/gwt-and-cross-site-jsonp-in-j2ee.html On Oct 9, 8:38 pm, eggsy84 <[EMAIL PROTECTED]> wrote: > Hi Adam > > I've finally worked it out and a lot of it is very much down to your > help!! > > What I wasn't reading on Dan's article was a very important part of > his Python server, basically the line: > > body = '%s(%s);' % (fun_name, file('json.js').read()) > > which as you quite rightly stated includes the damn function name and > is very important!!! > > So I have taken your advice and implemented my client side code as per > Dans article: > > ============ > > public void makeCall(String number) > { > String serverURL = ClientGlobals.CALL_SERVICE_URL+"callback="; > String callbackName = reserveCallback(); > setup(this, callbackName); > System.out.println(serverURL + callbackName); > System.out.println(callbackName); > addScript(callbackName, serverURL + callbackName); > > } > > public String reserveCallback() > { > while (true) > { > if (!callbacks.containsKey(new Integer(curIndex))) > { > callbacks.put(new Integer(curIndex), null); > return "__gwt_callback" + curIndex++; > } > } > > } > > /** > * <p>Adds the JSONP script to our widget so we can make XSS requests > baby</p> > * > * @param uniqueId The unique id of the call > * @param url The URL of our Request > */ > public void addScript(String uniqueId, String url) > { > Element e = DOM.createElement("script"); > DOM.setElementAttribute(e, "language", "JavaScript"); > DOM.setElementAttribute(e, "src", url); > scriptTags.put(uniqueId, e); > DOM.appendChild(RootPanel.get().getElement(), e); > > } > > public void handle(JavaScriptObject jso) > { > if( jso != null ) > { > Window.alert("Woohoo JSO is not null it bloody worked"); > } > > } > > /** > * > * <p>Sets up our Javascript cross site JSON call</p> > * > * @param model Handles our Cross Site JSON call > * @param callback > */ > public native static void setup(CallModel model, String callback) > /*-{ > $wnd[callback] = function(someData) > { > [EMAIL PROTECTED]::handle(Lcom/google/gwt/core/client/ > JavaScriptObject;)(someData); > } > }-*/; > > ============ > > Then importantly in my server side I have used the callback name in my > JSON output as you quite rightly mention!! :) > > protected void doPost(HttpServletRequest req, HttpServletResponse > resp) throws ServletException, IOException > { > String asyncCallback = req.getParameter("callback"); > String output = asyncCallback+"([{color: \"red\",value: \"#f00\"}])"; > > resp.setContentType("text/javascript"); > resp.addHeader("Pragma", "no-cache"); > resp.setStatus(200); > > PrintWriter out = resp.getWriter(); > out.println(output); > > } > > And its not hitting my handler > > Thank you very much for your help. I'm going to post a tutorial on my > bloghttp://eggsylife.blogspot.comand will credit help toward > yourself. > > Eggsy > > On Oct 7, 1:10 pm, eggsy84 <[EMAIL PROTECTED]> wrote: > > > Hi Adam > > > Thank you for this insight - I'll use Dans code for my client side to > > fix this and add the callback as a parameter! > > > Thank you for all your help! I'll let you know how I get on > > > Regards, > > > On Oct 7, 1:03 pm, Adam T <[EMAIL PROTECTED]> wrote: > > > > mmm, your code below doesn't really follow the pattern in the link of > > > your first post - however, I think I know why your handle method is > > > calling. The code below seems to use a timer to loop around checking > > > if something has been returned, if not it fires your handler with null > > > - which explains why you handler is called and you only see null. I > > > assume that if you add the method name to your response you would > > > eventually get your handler called with a value. > > > > I might misunderstand the code on the web site you link to, but I > > > personally would recommend using the code shown in Dan's article > > > (http://code.google.com/support/bin/answer.py? > > > answer=65632&topic=11368 ) for the client side. It works fine, > > > removes the need for a timer (which is going to take resource in your > > > application) and truly handles the asynchronous nature of the web. > > > > //Adam > > > > On 7 Okt, 13:46, eggsy84 <[EMAIL PROTECTED]> wrote: > > > > > I expect thats what I'm missing then! > > > > > My calling method is as follows: > > > > > public native static void getJson(int requestId, String url, CallModel > > > > handler) > > > > /*-{ > > > > var callback = "callback" + requestId; > > > > > var script = document.createElement("script"); > > > > script.setAttribute("src", url+callback); > > > > script.setAttribute("type", "text/javascript"); > > > > > window[callback] = function(jsonObj) > > > > { > > > > [EMAIL PROTECTED]::handleJsonResponse(Lcom/google/ > > > > gwt/core/client/JavaScriptObject;)(jsonObj); > > > > window[callback + "done"] = true; > > > > } > > > > > // JSON download has 1-second timeout > > > > setTimeout(function() > > > > { > > > > if (!window[callback + "done"]) > > > > { > > > > [EMAIL PROTECTED]::handleJsonResponse(Lcom/ > > > > google/gwt/core/client/JavaScriptObject;)(null); > > > > } > > > > > // cleanup > > > > document.body.removeChild(script); > > > > delete window[callback]; > > > > delete window[callback + "done"]; > > > > } > > > > , 1000); > > > > > document.body.appendChild(script); > > > > > }-*/; > > > > > I have adapted it from a useful guide here: > > > > >http://giantflyingsaucer.com/blog/?p=126 > > > > > Eggsy > > > > > On Oct 7, 12:24 pm, Adam T <[EMAIL PROTECTED]> wrote: > > > > > > I think what you are missing is the function name in your output from > > > > > the servlet. From what I see, you just return: > > > > > > [{color: \"red\",value: \"#f00\"}] > > > > > > when I would expect a response something like: > > > > > > mycallback([{color: \"red\",value: \"#f00\"}]) > > > > > > where the "mycallback" is the name of the function you add to the DOM > > > > > which calls your handleJSONResponse method - without returning a > > > > > function from your servlet, I'm not sure how your handle method is > > > > > being called. > > > > > > Also, are you defining your callback code to pick up the parameter, > > > > > e.g. > > > > > > public native static void setup(YourHandlerClass h, String callback) / > > > > > *-{ > > > > > window[callback] = function(someData) { > > > > > [EMAIL PROTECTED]::handleJSONResponse(Lcom/ > > > > > google/gwt/core/client/JavaScriptObject;)(someData); > > > > > } > > > > > }-*/; > > > > > > without the (Lcom/google/gwt/core/client/JavaScriptObject;)(someData) > > > > > part it won't pick up the returned data > > > > > > //Adam > > > > > > On 7 Okt, 10:14, eggsy84 <[EMAIL PROTECTED]> wrote: > > > > > > > Hi Adam, > > > > > > > Thank you for the reply it definately helps! when you say it needs > > > > > > to > > > > > > be well-formed javascript I have implemented a method that performs > > > > > > the following: > > > > > > > /* (non-Javadoc) > > > > > > * @see > > > > > > javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest, > > > > > > javax.servlet.http.HttpServletResponse) > > > > > > */ > > > > > > @Override > > > > > > protected void doPost(HttpServletRequest req, HttpServletResponse > > > > > > resp) throws ServletException, IOException > > > > > > { > > > > > > String output ="[{color: \"red\",value: \"#f00\"}]"; > > > > > > resp.setContentType("text/javascript"); > > > > > > resp.addHeader("Pragma", "no-cache"); > > > > > > resp.setStatus(200); > > > > > > PrintWriter out = resp.getWriter(); > > > > > > out.println(output); > > > > > > > } > > > > > > > Would that be sufficient? Well I ask the question but I assume not > > > > > > as > > > > > > with my implementation I successfully go back to my client handle > > > > > > method now but the JavascriptObject passed in is always null. > > > > > > > My client side handle method is very basic as a test (shown below) > > > > > > and > > > > > > I can confirm that when the claa is complete is definately hits this > > > > > > method so the glue between is wrong somehow? > > > > > > > public void handleJsonResponse(JavaScriptObject jso) > > > > > > { > > > > > > if (jso == null) > > > > > > { > > > > > > Window.alert("Unable to parse JSON"); > > > > > > return; > > > > > > } > > > > > > else > > > > > > { > > > > > > Window.alert("Well done Woohoo!!"); > > > > > > } > > > > > > > } > > > > > > > eggsy > > > > > > > On Oct 6, 9:28 pm, Adam T <[EMAIL PROTECTED]> wrote: > > > > > > > > Eggsy, > > > > > > > > To get it to work you need to get the plumbing right, and it's not > > > > > > > quite the same way as calling from code - btw, the example on that > > > > > > > page is aimed at client side not server side. The server is any > > > > > > > language you want as long as it returns a well-formed JavaScript > > > > > > > segment of the form: > > > > > > > > mycallback({....some json content....}) > > > > > > > > So your servlet would work as long as it returns something like > > > > > > > the > > > > > > > above. > > > > > > > > In this approach you don't call the servlet in the normal way > > > > > > > from the > > > > > > > program code, rather it gets called as a consequence of adding a > > > > > > > <script> tag to the DOM - this is what the addScript() method in > > > > > > > the > > > > > > > example code does. Once the script is added to the DOM the > > > > > > > browser > > > > > > > accesses the defined url of your service and expects a response. > > > > > > > As > > > > > > > the response is a JavaScript function, it will get evaluated in > > > > > > > the > > > > > > > browser. > > > > > > > > If you also define a function in the DOM with the same name you > > > > > > > expect > > > > > > > back in the server response, e.g. mycallback, and that function > > > > > > > calls > > > > > > > the GWT handle() function then the loop is closed. The example > > ... > > read more » --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. 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