A few days ago, I had issues installing ElasticPath on my Windows VMs : the installer’s window never showed up. At first, I suspected that the installer was simply not compatible withVirtualBox.

But things started to become really strange when I tried to debug the Java process launched by the installer (which was eating all CPU time) with Visual VM or JConsole. Both tools were unable to start.

After a quick search on Virtualbox bug tracker, here is the answer :

Any Java Swing/AWT application will crash if 3d support was selected in Virtualbox guest additions. (Virtualbox 3.2.X and Only on JVM > 1.6u6)

See this bug report for details : http://www.virtualbox.org/ticket/6873

My current cheat sheet for OpenVZ on Debian. Will be updated continuously. Comments are welcome.

Installation
apt-get install linux-image-...-vz

Getting Debian Lenny template

in /var/lib/vz/templates/cache :
wget http://download.openvz.org/template/precreated/debian-5.0-x86.tar.gz

Create VM

vzctl create VEID --ostemplate debian-5.0-x86 --config vps.basic

vzctl set VEID --hostname HOST --save
vzctl set VEID --nameserver DNS --save
vzctl set VEID --ipadd IP --save

Give internet access to VM
On host : Enable net.ipv4.ip_forward=1 in /etc/sysctl.conf

iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
iptables-save > /etc/iptab

Restore iptables on startup
(See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=434107)
Create /etc/init.d/iptables

#!/bin/sh
### BEGIN INIT INFO
# Provides: iptables
# Required-Start:
# Required-Stop:
# Default-Start: S
# Default-Stop: 0 6
# Short-Description: save/restore iptables rules
# Description:
# This script saves and restores iptables on
# shutdown and bootup. On sysv-rc systems: to
# disable saving on shutdown, remove
# /etc/rc[06].d/K20iptables. To disable restoring
# on bootup, rename the "S20iptables" symbolic link
# in /etc/rcS.d/ to "K20iptables".
### END INIT INFO
set -e

case "$1" in
start|restart|force-reload)
iptables-restore ;;
stop)
iptables-save >/etc/iptab
;;
*)
exit 1
;;
esac


update-rc.d iptables start 20 S . stop 20 0 6 .

Change template timezone
dpkg-reconfigure tzdata

Install vzdump
(From http://download.openvz.org/contrib/utils/vzdump/)
wget http://download.openvz.org/contrib/utils/vzdump/vzdump_1.2-4_all.deb
apt-get install liblockfile-simple-perl

Do a backup
vzdump --compress --suspend --dumpdir TARGET VEID

Change limits
Disk :
vzctl set VEID --diskspace 10G:12G --save

Memory :
vzctl set VEID --vmguarpages $((512 * 512)) --save
vzctl set VEID --privvmpages $((512 * 1024)) --save

Cores
vzctl set VEID --cpulimit 100 --save

CPU ratio
vzctl set VEID --cpuunits 500 --save

Pour une fois, on ne vas pas parler d’informatique ici, mais de réparation de machine à laver, en l’occurrence une Indesit WIDL 146 en panne après 5 ans de loyaux services.

Symptôme : Le programme séchage ne fonctionne plus : il tourne sans jamais s’arrêter. La vitre n’est pas chaude et si on force l’arrêt, le linge est toujours humide.

Solution : D’après le forum cité plus bas, c’est un problème de fusible. Dans mon cas c’est encore plus simple : les vibrations ont tout simplement sectionné le fil connecté à ce fusible.

Action :

• Dévisser les 2 vis à l’arrière, qui retiennent le panneau supérieur
• Faire coulisser le panneau supérieur vers l’arrière

On obtient ça (image empruntée au forum cité précédemment) :

• Le fusible est dans la gaine jaune, entouré en bleu sur l’image.
• Dans mon cas, un tire un peu sur le fil à l’une des extrémités de la gaine et ça vient tout seul, le cable est sectionné. Sinon, on prend un ohmmètre et on vérifie qu’il n’y a plus contact entre les connecteurs aux 2 extrémités de la gaine.
• On sort le fer à souder on répare, voir on achète un nouveau fusible
• On remonte… ça marche On a évité le réparateur et la tirade habituelle : “Faut en acheter un neuf, ça fait 5 ans, c’est normal vous savez…”

Source :
http://forums.futura-sciences.com/depannage/346484-indesit-widl-126-panne-fonctionne-sechage.html

Thanks to Mantis But Tracker and with some time spent to recreate issues for the latest commits, both Web Assemble Tool and Stateless Filter now have a changelog available.

WAT :
https://sourceforge.net/apps/mantisbt/webassembletool/changelog_page.php

Stateless filter :
https://sourceforge.net/apps/mantisbt/statelessfilter/changelog_page.php

This gives a better visibility on the activity and the latest changes/releases of these projects.

Working with Spring, Log4j and Tomcat, you may have faced the following error, which prevents your web application to start :

Logs in french :
org.apache.catalina.core.StandardContext start GRAVE: Error listenerStart
org.apache.catalina.core.StandardContext start GRAVE: Erreur de démarrage du contexte [/mywebapp] suite aux erreurs précédentes

Logs in english :
org.apache.catalina.core.StandardContext start SEVERE: Error listenerStart
org.apache.catalina.core.StandardContext start SEVERE: Context [/mywebapp] startup failed due to previous errors

This error seems to come without any additional logs. Webapp startup is interrupted but you can start the application from the tomcat manager successfully.

The explaination for our case are :

• We are using 2 context listeners : org.springframework.web.util.Log4jConfigListener and org.springframework.web.context.ContextLoaderListener.
• Log4jConfigListener automatically sets a SYSTEM property : webapp.root to share the application context
• On Tomcat, system properties are system-wide, thus are shared between applications
• If 2 applications are installed, the webapp.root value is invalid for the second one, causing the exception

Solution : define a unique webAppRootKey value for each application.

<context-param>
<param-name>webAppRootKey</param-name>
<param-value>app1</param-value>
</context-param>

See :
http://static.springsource.org/spring/docs/2.0.8/api/org/springframework/web/util/WebAppRootListener.html for additional information.

Note : Resin does not have this issue because it does not share system properties between webapps.

Working with large cookies and jetty, you may have faced this error :

2010-03-11 18:18:31.275:WARN::HttpException(413,FULL head,null)

This is because jetty allows only 4ko for HTTP request and response headers. Using large cookies is enough to reach the limit.

To add more room for headers, simply add <headerBufferSize>16384</headerBufferSize> to your connector configuration (16k should be enough).

Full jetty plug-in configuration :
<plugin>
<groupId>org.mortbay.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
<version>7.0.1.v20091125</version>
<configuration><scanIntervalSeconds>10</scanIntervalSeconds>
<connectors>
<connector implementation="org.eclipse.jetty.server.nio.SelectChannelConnector">
<port>8080</port>
<maxIdleTime>60000</maxIdleTime>
<headerBufferSize>16192</headerBufferSize>
</connector>
</connectors>
</configuration>
</plugin>

I just added a new WATBlock component to Web Assemble Tool Wicket adapter (webassembletool-wicket).

This is the equivalent of assemble:includeBlock jsp tag, which allows to include content from a remote web site into your application.

Now the Wicket adapter has the minimal components to be useable in a project (WATTemplate, WATBlock).

I’ve also added some ready-to-use demo content and template in order to ease WAT learning. These files already have WAT tags included (look at the html source to get block names) :

• Simple content
• Multiple content blocks
• 3 columns template

The website has yet to be updated.
Enjoy

Just relaying a ‘thank-you’ post from Stavros Kounis on the nebula newsgroup :

Hi all

Its was back to 2008 when we have decide to rely on nebula gallery widget for our project named “PosterGenius”[1][2].

Since then Nebula Gallery widget[3] was havy used in our application. Now PosterGenius is a finalist for the Best RCP Application for the 2010 Eclipse Community Awards.

I what to share this “recognition” of our work with the Nebula Team[4] and say a BIG “Thank you guys!!”

/stavros

[1] http://www.postergenius.com/
[2] http://skounis.blogspot.com/2010/03/nebula-gallery-widget-in-production.html
[3] http://www.eclipse.org/nebula/widgets/gallery/gallery.php
[4] http://www.eclipse.org/nebula/

It’s nice to see the Gallery widget being used in more RCP applications. This kind of feedback shows that Gallery is ready to be used in production applications, even if it is still labeled as ‘beta’ because of some missing features, like accessibility and full JFace support (Feel free to help ).

Thanks Stavros for using Nebula widgets
I’ve updated my Nebula Gallery page with screenshots and links.

I just finished publishing on sourceforge a simple filter named Java Stateless Session Filter which let you change the way your application use HTTP session without refactoring the code, or share user session between webapps while using the standard session API.

Several session stores are available out of the box :

• Cookie, with variants : plain (development only), Encrypted, JSON based
• Memcache
• Native session (when some attributes doesn’t need sharing)

The inital code is released under the Apache License v2.0 by Capgemini.

Status:
This code was written in a few days as a Proof Of Concept and was tested with Struts2, Wicket and JSF.

Feel free to test this filter and report success or issues. See the support page for project forums and trackers.

How it works:

Usage:
The project exposes a maven2 repository. To add this filter on your application, just add repository and dependencies to your project pom :

<repository
<id>statelessfilter-repository</id>
<name>Stateless Filter repository</name>
<url>http://statelessfilter.sourceforge.net/maven2/repository</url>
</repository>


<dependency>
<groupId>net.sourceforge.statelessfilter</groupId>
<artifactId>stateless-core</artifactId>
<version>0.1</version>
<type>jar</type>
<scope>compile</scope>
</dependency>


<dependency>
<groupId>net.sourceforge.statelessfilter</groupId>
<artifactId>stateless-cookie-plain</artifactId>
<version>0.1</version>
<type>jar</type>
<scope>compile</scope>
</dependency>


Then add the filter in WEB-INF/web.xml :

<filter>
<filter-name>session</filter-name>
<filter-class>net.sourceforge.statelessfilter.filter.StatelessFilter</filter-class>
</filter>

(...)

<filter-mapping>
<filter-name>session</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>


For additional details, see the complete documentation on sourceforge.

I’m testing Disqus.com as the new comment system for this blog. It should provide integration with Facebook, Tweeter and Google.

This service does not seem very stable, but since the standard wordpress system is still available when Disqus.com is down, this should not be an issue.

Feedback is welcome.