@Remotespots project was started a couple of months ago and and after some time all the technologies were updated to their current versions (Grails 1.2.2, GWT 2.0 which is a huge change from 1.7, and finally grails-gwt 0.5). Since we were busy w/ the features we ignored the upgrade but time has come to sent Remotespots to the wild, and we want it to be ready to its limits. Below you can find the steps and obstacles we encountered during the upgrade process. (I switched to Ubuntu from Windows XP, my headphones are still not working but at least I can open Eclipse under 60 seconds! so the things below is tested on Ubuntu 9.04)

• Download and change GRAILS_HOME to new grails version (1.2.2)
• Run grails upgrade
• Run install-plugin gwt (so that it installs 0.5)
• First obstacle

Error executing script CompileGwtModules: No such  property: usingGoogleGin  for class: _Events
gant.TargetMissingPropertyException: No such property: usingGoogleGin for class: _Events
        at gant.Gant$_dispatch_closure4.doCall(Gant.groovy:329)
        at gant.Gant$_dispatch_closure6.doCall(Gant.groovy:334)
        at gant.Gant$_dispatch_closure6.doCall(Gant.groovy)
        at gant.Gant.withBuildListeners(Gant.groovy:344)
        at gant.Gant.this$2$withBuildListeners(Gant.groovy)
        at gant.Gant$this$2$withBuildListeners.callCurrent(Unknown Source)
        at gant.Gant.dispatch(Gant.groovy:334)
        at gant.Gant.this$2$dispatch(Gant.groovy)
        at gant.Gant.invokeMethod(Gant.groovy)
        at gant.Gant.processTargets(Gant.groovy:495)
        at gant.Gant.processTargets(Gant.groovy:480)

To solve it, run grails clean command and empty ~\.grails\1.2.2\scriptCache folder. I found this solution from this link.

• Another problem you are likely to see is

  grails  GWT module ... may need to be (re)compiled

  To solve it, run grails compile-gwt-modules command and refresh firefox w/ ctrl+f5 OR alt+shift+r

• Last thing to be careful is, after started the gwt client with the command grails run-gwt-client, since GWT 2.0 get rid of hosted mode (finally), to see the changes on your code w/out restarting the server, add the suffix to the url ?gwt.codesvr=127.0.0.1:9997, from this link, you can find the solutions to the problems people have w/ the grails-gwt plugin.

For the close button, instead of adding a hyperlink from the java code, this time we used JSNI which enables you to integrate JavaScript directly into your application.

We have a class called GenericNotifcation in the package org.remote.dogan.client. When a noticition bar is needed,

public static void showNotification(String message, int seconds)

is called.To hide the bar the following method is called,

public static void hideNotification()

So, to make the JSNI close method call from js, we need to call the hideNotification java method from js.

To do this, we add amethod to register hideNotification method a js method for the handwritten javascript

public static native void exportStaticMethod() /*-{
$wnd.closeNotification =
	@org.remote.dogan.client.GenericNotifcation::hideNotification();
}-*/;

As a second step, we should call the method exportStaticMethod() to actually make the registration of the js method. We do this in showNotification method but for a generic case, onModuleLoad is good candidate.

public static void showNotification(String message, int seconds)

{
GenericNotifcation.exportStaticMethod();
...
}

So as the last step, we add the js call in the html template like the following:
<a title=”close this notification” onclick=’closeNotification()’ />x</a>

For further information, the documentation for GWT JSNI is here.

Memcache provides convenience to store a frequent query in memory, so that you don’t have to make the same execution over and over again. For the iPhone application I build (Fragman), I build a GAE/J backend for managing movie names, IMDB URLs, thumb images, video files, etc. It interacts with the Obj-c code via calls encoded in JSON.

Since the categories are updated so frequently (new trailer, top 250 , soap opera trailers), every time the user starts the application from her iPhone, the corresponding categories Id(key) lists are  created which includes all the aspects mentioned above,

what I see, after people start to use the application that, most of the time, the application got stuck with the time constraint of GAE and this causes inconvenience, so I decided to hold the category lists’s JSON in memory. Following is the code ,

this is the servlet for creating the JSON which is called after say upcoming movie list is changed. This servlet updates the memcached list

        List keyList = new ArrayList();
	static Cache cache;
	static
	{
		try
		{
			CacheFactory cacheFactory =

CacheManager.getInstance().getCacheFactory();
			cache = cacheFactory.createCache(

Collections.emptyMap());
		}
		catch (CacheException e)
		{
			// ...
		}
		//.....
                public void doGet(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException

	        {
                       //................
                       if(cache.containsKey(mode))
		       {
			     cache.remove(mode);
		       }
		       cache.put(mode, keyList);
	        }

                //........

          }

And this is the servlet that fetch the Fragman beans from the datastore with the given keys (key list is got from the memecached list)

          keyList = (List)cache.get(mode);

By doing this, I reduce the time that the servlet that creates the JSON takes.

The chart will show the remaining number of months in the current year.

• First download the jar from the project home page http://code.google.com/p/gchart/
• Put it under war/WEB-INF/lib and add the gchart.jar to your classpath
• Create a  Web Application project called it GChart-samples (I assume you have Google Eclipse Plugin and follow the basic steps from here)
• This step is for make-up, find GChart_samples.html under war/WEB-INF and clear the part between <body> tags.
• Open GChart_samples.gwt.xml and add the following line

  <inherits name='com.googlecode.gchart.GChart'/>

• Create a class in client folder called FirstChart and change it as the following

  package com.dogan.kaya.client;
  
  import com.googlecode.gchart.client.GChart;
  
  public class FirstChart extends GChart
  {
  	public FirstChart()
  	{
  		setChartSize(350, 350);
  
  		addCurve();
  
  		int[] data = { 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 };
  		for (int i = 0; i < data.length; i++)
  		{
  			getCurve().addPoint(i + 1, data[i]);
  		}
  		//curve customization
  		getCurve().getSymbol().setHeight(10);
  		getCurve().getSymbol().setWidth(10);
  		getCurve().getSymbol().setBorderColor("black");
  		getCurve().getSymbol().setBorderWidth(3);
  		getCurve().getSymbol().setSymbolType(SymbolType.LINE);
  		getCurve().getSymbol().setFillThickness(2);
  		getCurve().getSymbol().setFillSpacing(0);
  		//chart customization
  		getXAxis().setAxisMin(1);
  		getXAxis().setAxisMax(12);
  		getXAxis().setTickCount(12);
  		getXAxis().setHasGridlines(false);
  		getXAxis().setTickLocation(TickLocation.CENTERED);
  		getXAxis().setTickLabelFontSize(10);
  		getYAxis().setAxisMin(0);
  		getYAxis().setAxisMax(12);
  		//to get inteter values on y axis, be careful
  		//about the number of intervals it can be tricky
  		getYAxis().setTickCount(13);
  		getYAxis().setTicksPerLabel(2);
  		getYAxis().setHasGridlines(false);
  		getYAxis().setTickLabelFontSize(10);
  		//
  		update();
  	}
  }

• Open GChart_samples class and change it like the following

  package com.dogan.kaya.client;
  
  import com.google.gwt.core.client.EntryPoint;
  import com.google.gwt.user.client.ui.RootPanel;
  
  public class GChart_samples implements EntryPoint
  {
  	public void onModuleLoad()
  	{
  		RootPanel.get().add(new FirstChart());
  	}
  }

• My output is sth like that

ps:

some nice links about gchart are as follows:

1. gchart homepage
2. A simple tutorial at http://whatwouldnickdo.com/wordpress/264/simple-charts-in-gwt-with-gchart/