Another Wicket course coming up

I'll be doing the public Wicket introduction course from jweekend again on May 27 and 28. For more information see the link above or drop me a note.

Wicket root mounts

Just in case you missed it: I recently wrote an article that shows how to mount pages on the root in Wicket. As a lot of time went into creation the example application I posted the article on my employers blog.

Backup home directory to USB harddisk

As I am keen to install Ubuntu 9.10 on my work laptop, its time to do an extra backup of my home directory. My mp3 player has about 30 Gb free so I'll use that.

First attempt:

cp -R /home/erik /media/H300/Backup/

You wont believe how slow this is! All those little pesky files, we'll need to aggregate them.

Second attempt:

tar -cjf /media/H300/Backup/erik.tar.bz2 /home/erik

Waiting ... waiting ... Oops, that fails! The FAT file system on the mp3 player only supports files up to 2Gb.

After a long but fruitless search in the documentation of tar (and zip) for multi-volume archives options, I suddenly thought of the simplest thing that could work:

tar -cj /home/erik | \ split -d -b 1G - /media/H300/Backup/erik.tar.bz2.part

This creates a bunch of 1Gbyte files ending in part00, part01, etc.

You've got to love unix!

Wicket do's and dont's

Just published an article on my employer's blog: Wicket do's and dont's.

Extending my e-mail stack with Roundcube

I don't trust anyone with my most precious data: e-mail. That is why I run my own e-mail server. The server runs Ubuntu, Postfix, Dovecot and several tools for spam interception. I access my e-mail from several machines through the IMAP protocol (with TLS). Though any good IMAP client would do it is always Thunderbird (yes, even on my Mac).

It is however not always feasible to have Thunderbird around. Time to add an IMAP web client! Candidates are IMP, Squirrelmail and Roundcube. All of these projects continuously release security updates. So unless you go for the next (beta) Ubuntu release, the packaged version is almost always a few versions behind.

In the past I have already used IMP and Squirrelmail. IMP has a nice UI but was difficult to install. Squirrelmail looks really old, but has a huge amount of nice plugins.

So it became Roundcube this time. Roundcube is not out of beta for that long. But it does look really slick, almost as if it is a desktop app. I did go with the Ubuntu package after all. Lacking more documentation I had to figure out for myself that I needed to use /etc/roundcube/apache.conf as the basis for a virtual host file in the /etc/apache2/sites-available directory. After some smaller configuration tweaks in /etc/roundcube/main.inc.php I had the application as I wanted it.

One more thing: Roundcube (like IMP and Squirrelmail) continuously open and close new IMAP connections. This makes the site amazingly slow. The fix: package imapproxy. This package starts an IMAP server that caches IMAP connections to another IMAP server. Some small config changes, and Roundcube was a lot quicker.

More Wicket filter options

Wicket has this very clever idea to serve requests from a servlet Filter instead of a Servlet. The brilliance of it is that you can serve pages on the root of your context, but still allow the servlet container to process requests that Wicket has nothing to do with.

By default this works correct automatically. Incoming requests that are not recognized by Wicket are just passed through.

However, there is an optimization that is not very well documented. When you already know that certain paths are never going to be handled by Wicket (for example because you configured a servlet for them), you can tell the Wicket filter to ignore those paths in the same file as where you define the servlets: in the web.xml.

Example web.xml configuration:

<filter> <filter-name>wicket.filter</filter-name> <filter-class>org.apache.wicket.protocol.http.WicketFilter</filter-class> <init-param> <param-name>ignorePaths</param-name> <param-value>images/,rest/</param-value> </init-param> </filter>

This will let the Wicket filter immediately pass through to the servlet container for all URLs that start with http://host/app-context/images/ and http://host/app-context/rest/.

Note: make sure the paths are comma separated without additional whitespace.

Simon 2 in beta

Java Simon, simple java monitoring, version 2 is in beta. I am quite proud of this because firstly the major change in the version was a result of my performance investigations, and secondly it contains my Spring integration code. See the java simon pages for news, downloads, etc.