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IT-Essence
Monday Aug 25, 2008

Google tips and tricks

Today I found this article on a Dutch news site, which mentions several tips and tricks that can be used on the Google search site. [Read More]

Saturday Feb 09, 2008

Canon EOS 400D on Gentoo Linux

Finally I got my Canon EOS 400D (also known as Digital Rebel XTi) operational under Linux, thanks to this post. There were only two minor additional things I had to perform:

  1. Add myself to the usb group in /etc/group
  2. Changing the CAMERA variable in /etc/make.conf to CAMERAS

Thursday Feb 07, 2008

My _gvimrc

When working on-site for a customer, I often find myself forced to work on a Windows-based platform. Luckily, most of the time it is either possible to install vim or make use of a pre-installed version. This post contains my settings in the _gvimrc, such as color scheme, tab settings and window height and width

[Read More]

Thursday Nov 08, 2007

Blog moved and served by Tomcat version 6

After almost a week of absence, this blog is up and running again. Due to us moving to the other side of the street and an associated change of IP, it was difficult to get everything back in the air again. Note that the server name changed from "finance" to "it-essence", named after the name of my company.

I also grabbed this opportunity to upgrade to Tomcat version 6. After installation of the "tomcat-dbcp.jar" from a binary distribution in Tomcat's lib directory (Gentoo bug #144276), everything seems to be fine again.
 

Monday Sep 24, 2007

The role of pi and e in computer science

I once brought up the versioning policy of TeX and Metafont, which are increased by the digits of pi and e respectively every time a bug is found. According to Donald Knuth's page:

The latest and best TeX is currently version 3.141592 (and plain.tex is version 3.1415926); METAFONT is currently version 2.71828 (and plain.mf is version 2.71).

When I told a former system administrator about this, he immediately showed me another (coincidental) occurrence of pi and e:

$ perl -pi -e 's/search/replace/g' *.java

In the above example, all occurrences of "search" are replaced by "replace" in all "*.java" files. An excellent description of what you can do (and what you shouldn't do) with the above Perl trick is found on this page.

Does anybody else know some additional peculiarities concerning the use of pi or e in computer science? If so, please leave a comment with e.g. a reference to the source!

Monday Sep 17, 2007

Tunneling via SSH

In this post it is described how to set up an SSH tunnel on Linux/Unix systems as well as Windows equipped desktop PCs. A tunnel over SSH is ideal for making services on a remote network available to your local network (or the other way around), assumed that these networks can be connected over at least one port (port 22 by default for SSH). This way it is possible to disclose e.g. a service running on an arbitrary port on a remote network to an arbitrary port on your local network. Stated differently, any port can be "tunneled" via SSH through a firewall, as long as an SSH connection can be established between the two networks.

[Read More]

Thursday Aug 23, 2007

Disable firewall on Alcatel Speedtouch 510 ADSL modem

The firewall on the Alcatel Speedtouch 510 ADSL modem (firmware version  4.2.7.16.0) can only be disabled using the command line interface:

  1. Connect to your modem (e.g. "telnet 10.0.0.138" )
  2. Login + passwd (if password has been configured)
  3. Invoke "ip config firewalling=off"
  4. Invoke "saveall"
  5. Done!
In my case, it was also needed to configure a default server in the NATP (network and port address translation) section. This can be done using the web interface by going to the "advanced" settings, choosing NAPT from the left side menu and picking the default server tab. There I filled in the IP of my server (which is 10.0.0.150 in my case).

Wednesday May 30, 2007

Apache Roller that is serving this blog upgraded to 3.1

Today the software running this blog, Apache Roller, has been upgraded to version 3.1. A new feature that lets one add tags to each post and let the blog show a tag cloud has been enabled as well.[Read More]

Wednesday May 09, 2007

JavaFX: alternative for AJAX?

In Does JavaFX Spell The End Of AJAX? Andy Patrizio peeks at the AJAX would-be substitute from Sun Microsystems , JavaFX, that has apparently been introduced at the JavaOne conference held in San Francisco yesterday. Whether it is going to replace the well established AJAX remains to be seen, but following the developments around JavaFX will be interesting nontheless.

Monday May 07, 2007

Portal versus website

In issue 10 of the Computable, Norman Manley argues that many sites are incorrectly denoted as portals. This is due to the fact that portal is often misunderstood as "start page", whereas a genuine portal should provide easy access to information that you need from the inter or intranet, with an emphasis on you and need.

According to the characteristics outlined below, we can only conclude that the web does not feature many genuine portals yet. The two major characteristics that set a portal apart from a regular website are: 

  1. A portal is personalized, i.e. your portal looks different from my portal. It should offer information that is relevant to me only.
  2.  
  3. A portal is customizable. For example, as long my activities take place in the foreign exchange and money market, I am interested in the latest forex exchange rates, but the market may push me to switch to trading stock options any time, in which case I may want to access stock data.
The benefits of employing portal technology are:
  • SSO (Single Sign-On): one place to log on to all applications  offered by the portal.
  •  
  • Seamless access to different informational resources that are  frequently consulted. Consequently, many portlets in your  portal can be developed and maintained completely independent of one an other.
  •  
  • A personalized environment offering relevant information at the blink of an eye.
According to Norman Manley, portals should pass the "TomTom-test": only when every portal user is able to use the portal to effortlessly navigate to his/her final destination without any help, explanation or dedicated training (just like TomTomat does), your portal is likely to be used frequently. Otherwise you run the risk that you have spent your money on software that nobody will use.

Personally I would like to underscore this last sentence and add that you run the risk of having spent your money on a complex piece of software that nobody uses. From my last years of working with WebSphere Portal Server I can assure everyone that portal technology is significantly more complex than a regular (interactive) website. This does not only affect portal development, but also testing and deployment.

Only when the aforementioned benefits are key factors in your requirements, a decision to employ portal technology is justified.


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