In the server log files we found exceptions like this one:

2011-04-19 08:36:09,484 ERROR [de.absoft.portal.core.listener.PortletContextListener] Exception while parsing 'portlet.xml'
org.dom4j.DocumentException: Error on line 573 of document http://java.sun.com/xml/ns/portlet/portlet-app_1_0.xsd : src-resolve: Cannot resolve the name 'xml:lang' to a(n) 'attribute declaration' component. Nested exception: src-resolve: Cannot resolve the name 'xml:lang' to a(n) 'attribute declaration' component.

We figured out that the exception is thrown when this document on the Sun webpage is – for whatever reason – not reachable. Additionally this error may also occur if you try to start JBoss without an internet connection at all.

But the main problem is that before it throws this exception, it waits for a timeout. This leads to the extremely long startup time in this case.

As it is completely insane that the JBoss startup relies on a Sun server that obviously does not run very steadily, we searched for a solution.

The only reason for this issue was that the validation feature was enabled in code. So we just needed to remove these lines of code:

reader.setFeature("http://xml.org/sax/features/validation", true);
reader.setFeature("http://apache.org/xml/features/validation/schema", true);
reader.setFeature("http://apache.org/xml/features/validation/schema-full-checking", true);
reader.setFeature("http://apache.org/xml/features/validation/dynamic", true);

Of course, this validation feature is very useful for debugging reasons, but it should definitely be disabled for productive environments.

Did you also note JBoss startup problems due to this feature already yourself?

My Android app Energy Costs Calculator was selected as the best new Android app of this week.

I have to admit that I even did not know I was participating in any competition. So this e-mail of Vodafone was a very positive surprise.

I want to thank Vodafone for the price, a HTC Legend (Android smartphone):

Developing a toolbar for Firefox is quite easy: it’s all done by using XML, a little bit of CSS and especially JavaScript. The last one is also the only crux of the matter, because I really don’t like to develop in JavaScript. But anyway, it’s straightforward in this case.

I found a very good resource in the web. This tutorial explains the development of a Firefox toolbar in detail and saved me a lot of research work. After you went through the online tutorial, you should already have a fully-functional Firefox toolbar. There are only two things left:

Automatic online update

I wanted my toolbar to receive automatic updates from my webserver. But this is also quite easy by using the integrated update system of Firefox. On the same website there is a good tutorial for adding automatic update support, too.

Uninstall button inside the toolbar

The disreputability of toolbars is surely not least based on the fact that most of them are really hard to uninstall. Although Firefox provides uninstall support to the user already by using the add-ons manager, I wanted an uninstall button to be included directly into the toolbar itself. After doing some research in the web and at the Mozilla Developer Center, I got together the following piece of code that first successfully uninstalls the toolbar, second shows a webpage to the user (something like “We’re sad that you uninstalled…”) and finally tells the user that a browser restart is needed to finish the uninstallation:

try {
    var tb = document.getElementById('ABTools-Toolbar');
    var text = ABTools_ToolbarData["msg.uninstallToolbarText"].replace("%name%",
                                   ABTools_ToolbarData["toolbar.name"]);
    if (!window.confirm(text))
        return;

    var gExtensionManager = Components.classes["@mozilla.org/extensions/manager;1"]
                            .getService(Components.interfaces.nsIExtensionManager);
    var rds = gExtensionManager.datasource;
    if (gExtensionManager.uninstallItem) gExtensionManager.uninstallItem(ABTools_id);
    if (gExtensionManager.uninstallExtension)
        gExtensionManager.uninstallExtension(ABTools_id);

    ABTools_guid = "";
    ABTools_saveSettings();

    ABTools_LoadURL(getABToolsHomepageLink(9));

    alert(ABTools_ToolbarData["msg.restartBrowserText"]);
} catch(e) {
    if (ABTools_DebugMode) alert(e);
}

After going through these steps your Firefox toolbar is ready to get installed! It will work on Firefox Version 1.5 or higher, not depending on the version of the operating system.

In the next post I will go to the more complicated browser.

Contents of Post Series “Developing a Browser Toolbar”:

• Introduction
• Mozilla Firefox
• Microsoft Internet Explorer
• Installation System
• Summary