Of course the theory doesn’t fail, but it just doesn’t apply to SSD .

Setting up tzdata-java (2011j-0ubuntu0.11.04) ...
Setting up ca-certificates (20090814+nmu2ubuntu0.1) ...
Updating certificates in /etc/ssl/certs... WARNING: Skipping duplicate certificate brasil.gov.br.pem
0 added, 1 removed; done.
Running hooks in /etc/ca-certificates/update.d....
updating keystore /etc/ssl/certs/java/cacerts...
  does not exist: /etc/ssl/certs/DigiNotar_Root_CA.pem
done.

For those living outside the Netherlands: DigiNotar was a issuer of ssl and pki certificates, similor to Verisign. Their main customer was the Dutch government. Turned out DigiNotar was hacked by Iranian hackers, but not only that, the hack happened a few months ago but they decided not to inform their clients. In the mean time, Dutch governmental communication wasn’t as secure as you might hope.
Of course the Dutch government did perform audits on DigiNotar – sort of, they outsourced the audit to the great company PwC, who verified that all of their procedures were correctly written down in Word documents with proper headings and jargon that pleases business consultants (quote from the DigiNotar website: ‘Certificering ETSI door PricewaterhouseCoopers  (november 2010 – november 2013) ‘) Of course they didn’t look at the actual software and IT security – why would anyone care about such technical details?

For more information, I found the following timeline.

The problem in solving such a Serializable exception is finding the field that is not Serializable. The stacktrace of java doesn’t help much. Fortunatelly, after some searching I’ve found the solution, in the comment of blog posting: add the option -Dsun.io.serialization.extendedDebugInfo=true to the JVM startup parameters.
Now the stacktrace gives you the exact fieldname or expression that is causing the problems, as you can see in the example below:

2011-07-23 21:44:50,362 ERROR [http-8080-1] [] org.apache.wicket.util.lang.Objects - Error serializing object class nl.gerbrandict.forum.AdminPage [object=[Page class = nl.gerbrandict.forum.AdminPage, id = 2, version = 0]]
java.io.NotSerializableException: org.springframework.beans.factory.support.DefaultListableBeanFactory
- field (class "org.springframework.orm.hibernate3.HibernateTransactionManager", name: "beanFactory", type: "interface org.springframework.beans.factory.BeanFactory")
- object (class "org.springframework.orm.hibernate3.HibernateTransactionManager", org.springframework.orm.hibernate3.HibernateTransactionManager@10fd8ce3)
- custom writeObject data (class "org.springframework.transaction.interceptor.TransactionInterceptor")
- object (class "org.springframework.transaction.interceptor.TransactionInterceptor", org.springframework.transaction.interceptor.TransactionInterceptor@2c96cb51)
- field (class "org.springframework.transaction.interceptor.TransactionAttributeSourceAdvisor", name: "transactionInterceptor", type: "class org.springframework.transaction.interceptor.TransactionInterceptor")
..
        - field (class "nl.gerbrandict.forum.AdminModel", name: "person", type: "class nl.gerbrandict.forum.Person")

(note: not publishing the entire stack trace and using some sample dummy field/classnames).
Although I haven’t tried, enabling this option in production is most likely a bad idea, because Serialization is already a pretty inefficient process without any debugging information enabled. In my case, I was using a PropertyModel somewhere, using non model as target object.

• My homepage is running WordPress, a popular open source weblog.
• There are a lot of plugins for WordPress, of which one is the openid plugin. By going to the administration screen and then to the section plugins, you can install the openid plugin easily by entering openid in the search box.
• After installation, setup a default account.
• Now I can authenticate myself to any site that uses openid, by just entering http://www.gerbrand-ict.nl !

WicketMessage: org.apache.wicket.WicketRuntimeException: component myForm:myTable:editor not found on page nl.gerbrand-ict.gui.HomePage[id = 4], listener interface = [RequestListenerInterface name=IActivePageBehaviorListener, method=public abstract void org.apache.wicket.behavior.IBehaviorListener.onRequest()]

Root cause:

...

In place of the … there was a full stacktrace, which information that’s not not relevant for this posting.

Turned out the solution was pretty simple, but the cause isn’t that easy to find and is quite a good example how some design decisions in Wicket aren’t considered as clean.

I’m using Ajax-features of Wicket extensively.
I was creating a table, which contained editable fields (AjaxEdiableLabel). This would allow the user to click on a field in the table, to edit the content.
Somewhere I had the following code:

target.addComponent(item);
if .. needed .. {
target.addComponent(myTable.this);
... make item invisible
}
super.onSubmit(target);

The super.onSubmit belonged, in this case, to AjaxEditableLabel. I found out the super.onSubmit() would call target.addComponent(this); to update the editable label itself. As you could see, in my code I’m telling wicket to update the component that’s the parent of the editable label also.

In this case, the code caused wicket to first update the parent-panel, which in this case makes the child-component invisible. Then the wicket tries to redraw the child-component, which is then invisible. That will trigger the above error.
Unfortunately, solving this error isn’t quite easy in all cases. Especially when you’d use a AjaxSelfUpdatingBehaviour you can have little control on the redrawing order.

Fortunately I found a good tip on the wicket mailing list to get rid of the exception. Add the following code your Wicketapplication class (the class that extends org.apache.wicket.protocol.http.WebApplication):

    @Override
    protected IRequestCycleProcessor newRequestCycleProcessor() {
    	//Tip from http://apache-wicket.1842946.n4.nabble.com/WicketRuntimeException-component-not-found-on-page-td3055902.html
    	return new WebRequestCycleProcessor(){
    		public IRequestTarget resolve(final RequestCycle requestCycle,
    				final RequestParameters requestParameters) {
    	        try {
    	            return super.resolve(requestCycle, requestParameters);
    	        } catch (InvalidUrlException e) {
    	            if (requestCycle.getRequest().getURL().contains("LinkListener") || requestCycle.getRequest().getURL().contains("BehaviorListener")) {
    	            	log.warn("Couldn't process event, is ignored because of: "+e.getMessage());
                        //ignore exception
    	                return new PageRequestTarget(requestCycle.getRequest().getPage());
    	            } else {
                        //normal operation
    	            	throw e;
    	            }
    	        }
    	    }

    	};
    }

The above code will ignore all of the exception that occur when wicket tries to do something with an component that’s no longer available because of an ajax-update. Of course this fix isn’t very nice, hopefully later versions of Wicket fix the error all-together when Ajax-support is improved. For now, this seems the best solution.

Roger gave an overview of the new JavaFX 2.0, the road-map and the planned features. The software seems to be developed in an agile manner: the dead line is fixed, as is policy at Oracle (not meeting a dead line means exit for the responsible executive), but the final set of features is not.
The preview is available now for a limited audience, in May the first public beta will be released and in November the final will be available.

The most important news I heard:

• JavaFX 2.0 will be a library (jfx.jar), rather than a separate scripting language JavaFX. The language works in the language Java of course, but you can use the language Scala, JRuby, Jython or other languages available on the JVM. JavaFX script is end-of-life. Fortunately, the syntax of the library calls is quite similar, and there’s a program to translate JavaFX script into equivalent Javacode. Curiously, the translator, FX Translator, is written in Scala.
  Update 2011-06-15: I only heard about the fx translator at the here mentioned presentation. I could find little references to the translator: a back-reference to this posting (sigh) and the fxtranslator mentioned shortly in this posting on DrDobbs.
  If you want to use the FXtranslator, you’ll have to contact Oracle for now. I guess Oracle will release the automatic translation tool in some time too.
• The Swing-controls can be used from JavaFX 2.0. The ‘traditional Swing’ is now in maintenance mode, Oracle won’t create an new features for the original Swing library. Meaning, if you want to develop Swing applications, or more generally, desktop applications in Java now, you can best get the beta or coming GA of JavaFX.
• JavaFX 2.0 will be available on neither the Mobiles nor Televisions! Oracle has accepted (Sun’s) loss, and will only focus on the desktop for the time being.
  JavaFX seems practical on tablet-devices. However, since most tablet devices are enlarged mobiles (running a mobile os) ratter than flattened laptops (running a full desktop os), you can’t use JavaFX on any of those devices for the time being.
• The JavaFX is supported on the MS-Windows platform only for the coming time, (but) it will run on Mac, Linux or other platforms unsupported. This means, you might miss the hardware acceleration when not using Windows. Mind you: Roger was using a Mac while doing his presentation and demonstration the code-samples so the MS-Windows-only support might not look as dramatic as it seems at first glance.
• Of course JavaFX runs on the JVM 6 or higher. If all goes well, JavaFX will be part of JDK 8. Before that JavaFX can be downloaded as a plugin before from java.com, which will be not to painful for users, especially if they already have some version of the Java-plugin installed.

The JavaFX SDK contains a set of sample application called ‘Ensemble’. Roger presented a few impressive programs, and showed the source code. The audience, including the Oracle employee hosting the event was very tech oriented so everyone was eager to see the code of all the nice examples.

Furthermore, Roger frequently mentioned Podcasts. I have yet to listen to them, but maybe if I have some time left. Should find a way to broadcast audio while doing the dishes.
All in all a nice event. Oracle may turn JavaFX in something that might be practical and usable on a limited number of platforms, ratter then trying to take over the world (or more specifically taking on Android, Flex, Apple IOS).

As you might notice, I’ve got no code examples or screen-shots. I hope to get access to the beta release of JavaFX 2.0, I’m quite interested in trying out all those nifty things, and expect some nice blog postings on JavaFX soon!

Update 2011-06-01: The public beta of JavaFX is out! I’ve published on JavaFX on the Xebia-blog.

See code as design for the source.

Here’s the example taken from the Mozilla DevCenter:

  <label value="Enter Name" accesskey="e" control="myName"/>
  <textbox id="myName"/>
  <button label="Cancel" accesskey="n"/>
  <button label="Ok" accesskey="O"/>

Both buttons as well as the input box can be accessed by ALT+E, ALT+N, ALT+O on Windows or CTRL+E, CTRL+N or CTRL+O on a Apple-Mac.

This is quite easy to program, and works for all popular browsers (including Internet Explorer, Safari or Firefox).
There might be cases where you want to execute some javascript when an accesskey is hit, for example to fire a java-event. Almost all webapplications use javascript one way or another. Fortunately, you don’t not complitated key-event-handling javascript to do that, just use an empty link:

<a href="#" accesskey="y" onclick="some javascript"> </a>

The javascript is executed when the acesskey is hit, this case an ALT+y on Windows. The link is not displayed, so you’re free wetter or not to display a button, link or anything within your web-application.