WORKIT website now detects duplicate usernames; gives error messages

The WORKIT website now gives error messages properly for two common reasons:

1. Duplicate username
2. Empty fields

I have put up the code here since Blogger's code highlighting system isn't too good.

Change to a new DB server

1. Tis the day the WORKIT website moved to a new DB server, the shared MySQL server ... so we don't intrude on department MySQL server space. Requires a bit of recoding on my part to get the WORKIT website working with the new server.
   
2. Also, found that users can create duplicate entries with same username - that's a no-no. Need to fix this.
3. The Physics Machine Shop and I played phone tag today - we finally decided to meet on Thursday to finalize the hardware setup for the remaining baseline kits.

vi / vim extra tabs during paste - solved

I've had this annoying problem with vi / vim ever since I started to use it - whenever you copy text and paste it into vi or vim, it indents each additional line with an extra tab, rendering it completely unreadable and requiring manual editing.

Luckily, I was able to find help on Google groups and the Wikia Vim pages. Solving this problem is as easy as typing in the command:

:set paste

That worked for me!

Wireless cards, antennas and connectors

Today I hunted down a wireless antenna-cable combo to go with our wireless card, the Atheros-based Gigabyte GN-WIAG02.

I didn't realize that there were different forms of cables and antenna for wireless cards, so I had to learn more about these.

I found out on Hyper Link Tech that there are several types of these. Because the Gigabyte card is a 802.11 b/g, which runs on the 2.4GHz frequency, what I needed was a 2.4 GHz rubber duck antenna. 5 dBi seems to be fine for the WORKIT testbed.

There were some helpful pages on gumph.org and Seattle Wireless that helped me find out more about the antenna, cables and connectors that are needed for wireless.

It appears that the most common connector for the miniPCI based wireless cards is the MMCX connector.

Finally decided to get the AOpen wireless antenna, which appears to have the antenna as well as the cables needed to fit the antenna onto the kit.

Rich UIs in Java: themes and fade animations

I was looking for ways to improve the look and feel of Java applications - for presenting my Java-based research work as a nice-looking app and for demos. I was inspired by some of the Adobe AIR themes out there, and I found some interesting stuff.

Among the many Swing Pluggable Look-and-Feel solutions is one that really stands out - Substance. It looks absolutely phenomenal, with a variety of options and customizations, plus its open-source. It easily stands out as a must-use PLAF for Swing. Take a look at some Substance screenshots.

There's that for themes ... but how about fade effects and transitions?

A little bit more searching reveals the animation layer, which includes transitions - in fact, automated transitions with no changes to app code! You need to see the above link for yourself to believe it.

Apparently, this fade animations is part of the laf-widget project now.

insmod, kernel versions, modules and Linux distros

The joy of working with kernel versions and kernel modules.

So after spending a long time finally getting a modpost program running so I could build kernel modules, I was finally able to get them to compile. However, I found that the modules were not loading - insmod and modprobe gave a very unhelpful "-1 Invalid module format" error.

A little bit of searching around for "kernel modules" lead me to the helpful Linux Loadable Kernel Module HOWTO. A page titled Technical details provides the full details about how to find information about the module.

I was able to confirm that the module had compiled properly, and that it was atleast displaying the right meta-information. So what had gone wrong?

A search for the actual error message "invalid module format" led me to a forum discussion on Linuxquestions.org about insmod, where one poster suggesting using 'dmesg' to find out the details of the error.

Excellent information. A line in dmesg shows:

No module found in object
kaodv: version magic '2.6.20.1 preempt mod_unload 486'
should be '2.6.20-486-voyage preempt mod_unload 486'

Perhaps because I used the Debian Voyage kernel instead of the Voyage kernel sources? :( And after all the trouble I went through in finding a corresponding kernel source and building the tree and the toolkit...

Maybe there's a way to just rename just the kernel name, since everything else seems to match ... stay tuned.

The insmod / modprobe hurdle

Today, I hit a brick wall with insmod/modprobe in installing/setting up AODV on the Linux kernel.

I was able to successfully compile the module, including the kernel object files. It appeared that the modpost compilation/linking worked perfectly as well.

However, a problem came up when running the start.sh script provided - it said that it could not find the "kaodv" module, which had been compiled in the current directory.

Perhaps it had not been loaded into memory properly. However, insmod /modprobe failed to find and load the module as well.