Life’s an ocean with too much commotion

he Groupwise Client version 6.x that is available for linux is consuming too much memory. The Groupwise Client version 7.0.1 is also available but that user-friendly for installing on a distribution other than SuSE (Novell).

Follow this guide to install the groupwise client version 7.0.1 on a Ubuntu Hardy distribution. Note that this procedure may also be valid for other (debian-package supported) distributions, but it has only been tested on Ubuntu Hardy.

• Download the groupwise client 7.0.1
  wget -P /tmp http://nsn.uvsc.edu/GWClient/gw701clnxm.tgz

• Untar the contents. The tarball contains two RPM packages.
  tar -zxpf gw701clnxm.tgz -C /tmp

• Convert the Groupwise Client RPM package to a debian package with alien.
  sudo alien -d /tmp/image/2006.06.13/client/linux/novell-groupwise-gwclient-7.0.1-20060613.i386.rpm

• Install the newly created debian package
  sudo dpkg -i /tmp/image/2006.06.13/client/linux/novell-groupwise-gwclient-7.0.1-20060613.i386.deb

• This will install some files into /opt/novell/groupwise/client

• Now we have to update the java runtime environment for this Groupwise Client. On my system this only worked with the Java 6 JRE from Sun.
  rm -rf /opt/novell/groupwise/client/jre
sudo ln -s /usr/lib/jvm/java-6-sun/jre /opt/novell/groupwise/client/jre

• Place the desktop icon on your desktop
  cp /opt/novell/groupwise/client/gwclient.desktop ~/Desktop/

Monday I went to Javapolis in the Metropolis Business Lounge in Antwerp. It’s a yearly event with several conferences, talks, workshops and BOF’s of projects related to Java. Personally I’m not a Java web framework lover. It’s hard to choose which framework you will need for your kind of web application, and knowing one specific framework doesn’t mean you know them all, on the contrary.

Monday morning I went to see Maurice Naftalin talking about Java Generics and Collections. Maurice also contributed in writing the O’Reilly book with the corresponding name. Although I was familiar with using generics in Java, I’ve learned some nifty tricks to have more exceptions detected at compilation time. The second part of his talk, Collections, was less interesting for me. He went pretty fast over all available collections and their performance. I’ve made a quick reference card with all available collections and for which purpose they can be used, together with their performance for every action (add/remove, select, iterate).

In the afternoon I went to see Google API’s by Dick Wall. He talked about the Google library which extends Generics and Collections. They kindly introduce closures (which is the main reason why I started to program in Ruby a year ago) by specifying filter functions in code blocks. These filter functions allow to manipulate the contents of collections, without having to know how to iterate over a collection. With the use of Generics you avoid having ClassCastExceptions in these inner filter functions. The second part of his talk was about the Google webservices. They use Atom feeds for transporting webservice contents. These Atom feeds can be controlled directly by XML or via a Google library. It’s pretty straightforward.

After the Google API’s talk, I went to see jBPM and Hudson, a continuous integration tool. jBPM gives you the ability to define workflows in Java. Every node needs some input and gives some output, based on the output you can let it direct to a next concept. The talk was given by someone who has implemented a jBPM workflow for a project, but she failed to explain the concept and how it’s all composed and executed. She just explained what it did for her project and showed some graphics which gave no meaning outside her project’s context.

Hudson was promising, because I googled it before I went to the talk. I’m looking for a continuous integration tool that can have distributions for kinds of software that needs a specific environment for getting it build. Triggering remote builds can be done via various ways. They all use SSH remote commands for executing a command or script that builds specific software on a machine. This means that the connection needs to be open while it’s building. Output of the build command is constantly send over the SSH connection. I’m looking for a client/server tool where the remote execution task is given to the client tool which executes a certain task. When the task is completed, the results (logs, artifacts, …) can be pushed to the server and can be processed and displayed. The main developer of Hudson, Kohsuke Kawaguchi, didn’t know exactly how it was done, but it was something with SSH…

Summarized, it wasn’t a thrown away day, I got a free T-shirt (apparently everyone got a XL sized T-shirt), and I learned some new things about the cores of Java.

By the way, you can see recordings of most of the talks on Parleys.

Today I’ve discovered an interesting feature of my Nokia N95 mobile phone: it can read barcodes!
I’ve tried to read them from books, pens, … but it didn’t work. After some googling I’ve discovered that these barcodes need to be encoded by one of these two methods:

• Datamatrix
• QR Barcode

The Nokia N95 tries to scan and decode the encrypted image. You can encrypt up to 2,335 alpha-numeric characters with Datamatrix and 4,296 alpha-numeric characters with the QR Barcode matrix code. Unfortunately the Nokia N95 only supports messages with maximum 90 alpha-numeric characters.

Nokia 95 recognizes the decoded content as URIs, to which you can surf; numbers, to which you can call, or just plain text.

Click here to find an open source tool, written in C, which will output these data matrices in various formats.

Yesterday I’ve searched for a mobile application that allows me make VoIP calls using my existing accounts (Google Talk, MSN, Skype, …).
This will enable me to use the same device (my mobile phone) to make calls:

- via GSM network
- via SkypeOut
- via VoIP

Fring is a free tool which does just that! It looks for various access points (WIFI, GPRS, …) to connect to (if your mobile phone supports it of course).
Now I only have to extend my address book with people that also use the VoIP services of Skype, Google Talk, MSN and not just for chatting

Some months ago I’ve bought a Nikon d70 (second hand).

Since two weeks my camera is having some green pixels on every picture I take, especially on pictures where it’s dark or with a great exposure value.

I’ve created a script that will parse a picture and interpolate saturation, hue and luminosity values from the second left and second right pixel. So if you have a hot pixel at x,y, it will use the interpolated HSL value of pixels at positions x-2,y and x+2, y. When the given coordinates of the hot pixels are out of range, it will assume the picture is in landscape position and flip the x and y coordinates. With an extra option, it will interpolate all pixels from position x,y to x,bottom of picture. This was necessary because at every picture I took, there was a weak green line visible to the bottom of the picture.

To parse the image files, I use the rMagick library.

Click here to download the hotpixelcleaner gem.

Note: This script has been created to fulfill my needs, but comments are welcome of course.

Here’s a short howto:

$ sudo apt-get install librmagick-ruby1.8
Unpacking librmagick-ruby1.8 (from .../librmagick-ruby1.8_1.13.0-1_i386.deb) ...
Setting up librmagick-ruby1.8 (1.13.0-1) ...
$ sudo gem install hotpixelcleaner-0.0.1.gem
Successfully installed hotpixelcleaner, version 0.0.1
$ hotpixelcleaner --help
Usage: /usr/bin/hotpixelcleaner -f <imagefile>

Options are ...

--co (-c)
Coordinates of pixel to transform 'x,y'
--help (-H)
Print help information
--image (-f)
Use this image file
--out (-o)
Filename to write results to
--to-bottom (-b)
Process image from the given coordinate to the bottom of the picture
--usage (-h)
Print usage information

$ hotpixelcleaner -c 5,5 -f foo.jpg -o bar.jpg -b
Image has been saved to bar.jpg