# Yenya's World

## Presentation style

I have already discussed problems with creating a presentation in Beamer. When we have talked about the presentation style, Mirka has told me about an interesting approach to the slides-based presentation:

Some people use a simple rule: one word per slide. It may seem too little, but seeing some YouTube videos has proved otherwise. There is even a (Japanese-based :-) term for those short talks: Pecha Kucha. Also, I have found a very interesting presentation (by its style, not only by its contents): look at Dick Hardt's OSCON 2005 keynote (warning: probably not suitable for epileptics; thanks to Mirka for showing this to me :-)

For conference talks, it may help. While I did not use such style for my XXXI. EurOpen slides, I have much shortened the text, and made an additional dynamics by using covered parts of the slides, changing colors (red-emphasized words in some phases of the frame), and pictures which were only vaguely related to the topic. I wonder how the evaluation marks from EurOpen will look like (as of this writing it is not published yet).

I also wonder whether such presentation style could be used for regular university lectures, which should sometimes have to be more in-depth.

## 7 replies for this story:

### Peter Kruty wrote: Pecha Kucha

Yea, I heard about this style as well. It is a bit similar to this one: http://www.perl.com/pub/a/2004/07/30/lightningtalk.html But I think it really depends on the situation and audiance.

### Yenya wrote: Re: rz

Well, I think Dick Hardt's style is not suitable for university lectures. However, I have been thinking about shortening the text on my slides, and splitting the slides (increasing the font size). For example, I have some 150 slides for 2 hours x 13 weeks lecture, while ing. Brandejs has 450 (shorter) slides for the same timeframe. I think colors and an occasional image or graph can help too. However, you are right that one word per slide is too low for an university lecture.

### Milan Zamazal wrote:

I always disliked fast-slide-changing-show lectures. Classic board was better because it contained more displayed information and it persisted there longer so it was easier to track the lecture or to refresh lost context (even after one awoke from microsleep:-). Perhaps a good slide show would contain just a single slide spread over a big wall, with current topic highlighted together with its context places.

### Yenya wrote: Re: Milan Zamazal

I think the main cause of micro-sleeps is exactly that: you can read in advance what the lecturer will say the next moment, so you quickly get bored. On the other hand, the context of "where in the whole lecture we are" is important. Beamer allows this context to be typeset as a headline or a sidebar (current section and subsection name). Also, slides and lecture notes for further studying can be two different things.

### Spike411 wrote:

Peter Saint-Andre from XMPP Standards Foundation (you all know Jabber, right?) uses one-word-per-slide style as well. That's the only person I've seen to use it so far and I'm tempted to try it too.

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## Non-ASCII Basic Authentication

We use a HTTP basic autentication for authenticating users to IS MU. It is most widely supported in clients, and it does not have some security problems which cookies have. Recently, while implementing a better method for storing passwords in IS MU, which would allow passwords of an arbitrary length, I have discovered the following problem:

I wanted to use this change to not only allow passwords of arbitrary length, but also to allow non-ASCII characters in passwords. However, reading the HTTP specification, I have not found in which charset is the Authorization: HTTP header supposed to be sent. Experiments showed that for example MSIE sends the password in the client's native encoding (windows-1250 in this part of the world), regardless of the charset of the previous 401 page.

What is worse, my Galeon (so probably all Gecko-based browsers too) mangle the password into something totally unreadable: for example, when I tried to send an user name "kas" and a password "asděščřžýáíé", the Authorization: header from Galeon contained the base64-encoded string "a2FzOmFzZBthDVl+/eHt6Q==" (decoded to bytes it is 6b 61 73 3a 61 73 64 1b 61 0d 59 7e fd e1 ed e9). Total crap, even with a newline! It looks like these bytes are the lowest bytes of the Unicode codepoint number of the character in the password. No UTF-8 or something, just codepoints truncated to 8 bits.

So we will stay with ASCII-only passwords, as we do not want to affect the accessibility of IS from various devices. By the way, did you know that Apache has its own proprietary algorithm for MD5-based password hashing? Talk about reinventing the wheel.

## 0 replies for this story:

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## EurOpen 2007

XXXI. EurOpen is over. I think the conference was quite interesting. My presentation was in the "Operating systems and desktops" section.

There was a presentation on OpenSolaris with some interesting points, altough they still mostly repeat their old "ZFS-Dtrace-Zones-WeAreStableWhileLinuxIsNot" mantra. The FreeBSD presentation was quite sad: they apparently do not even have working software RAID-5 in their new device-mapper alike, and the author seemed to be disappointed with the state of FreeBSD as an operating system.

Altough the section was originally meant to summarize the state of desktop support in modern kernels, only my own paper was on topic (I talked about things like udev, HAL, inotify, etc.). In my talk I have said that server kernels are generally less interesting, because the desktops have usually more varied usage than (most) servers, which often only run a single application like Oracle or Postfix for their whole lifetime. Interestingly enough authors of both OpenSolaris and FreeBSD presentation explicitly declined to talk about desktops, but still declared that Linux is unstable while their OS is stable. Oh well.

Anyway, here is my paper and slides, and also slides for my other talk The Linux Kernel in the Last Few Years (I have prepared this talk instead of Jirka Kosina, who could not attend the conference).

## 1 replies for this story:

### Vasek Stodlka wrote:

Hmm, i have read your slides and now I finally understand how does the HAL/udev/sysfs things work - thanks. I got lost somewhere between statical /dev and devfs - then udev went totally around me. I think it is good, because the best problems are the problems, which you do not have to solve and I think udev is one one of these - it "just works" in all Linux distributions I currently use.

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## Geocaching

In EurOpen, my roommate had a GPS and was into this Geocaching thing. So we have tried to find some nearby caches. During one afternoon we have found five caches, and I've got a Geocoin[?].

It was quite interesting, we have visited places which we would not normally visit. However, the weather was quite bad (fog, rain and snow), so we could not appreciate the landscape views. I hope I get my own GPS soon, and maybe I will even try geocaching myself.

## 4 replies for this story:

### Vasek Stodlka wrote:

Hm, I see this "sport" for a first time and it is really interesting for me. It may be a reason to buy a GPS. Unfortunately I have no money - my car is currently in service (to replace brakes, cooling fluid, and radio antena) I am expecting an invoice with a fear...

### Stepan wrote:

If you are interested in brainpuzzles like Tmou, you can enjoy some very good mystery caches... IE Enigma serie.

### Věroš wrote:

Yes, and usually you visit the interesting places from very unexpected directions :-) You even don't need to own GPS. We tried to measure position accuracy on mapy.cz and it's surprisngly very high. Y

### Yenya wrote: Re: Věroš

Actually, I have also thought about GPS-less geocaching, but could not find a suitable map. I will try mapy.seznam.cz, thanks for a hint!

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## Beamer

Next Tuesday I will have a presentation in the XXXI. EurOpen.CZ conference. I took this event as an opportunity to learn a new presentation software. In the past I have used several presentation software tools. From plain TeX (presented using xdvi(1), or later evince), to MagicPoint.

The candidates were OpenOffice.org's Impress, and Beamer. Since I would like to be able to enter and edit text using vim(1) or at least with vi-like keyboard shortcuts, I have decided to try Beamer. So far it looks nice and configurable (and their manual even had some interesting presentation tips!). There are only two drawbacks:

The first one is that it is TeX-based, so the ugliness and unorthogonality of the TeX command set sometimes cannot be hidden (I am speaking about \begin{frame}[fragile], or the fact that you cannot use \pause in some environments - like matrices in math).

And the second one is, that it is LaTeX-based, and LaTeX, as we all know, is even more disgusting than - say - XML. For example, look at the following code which describes a single frame for MagicPoint:

My first slide

The things I want to talk about:
This one
That one
and also those over there
%page


... and now the equivalent in Beamer:

\begin{frame}
\frametitle{My first slide}
The things I want to talk about:
\begin{itemize}
\item This one
\item That one
\item and also those over there
\end{itemize}
\end{frame}


Hope you see the difference. It is about 80 characters more on each slide. Since the Beamer output looks quite good, I am thinking about writing a conversion tool from the MagicPoint syntax to those verbose LaTeX environments.

## 2 replies for this story:

### Martiner wrote:

Best presentation tool ever is Slidy http://www.w3.org/Talks/Tools/Slidy/

### Yenya wrote: Re: Slidy

Slidy? Probably unusable. No easy way of generating handouts or printed version (the same problem has MagicPoint). No easy way to keep formating under control (even their sample presentation overflows the page length on my system). \$deity knows what happens when the presentation is done using a different screen resolution than on which it was prepared. No easy way to keep line breaks under control.

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## Another Time Eater

Do not click on the following link: The Impossible Quiz. You have been warned.

## 2 replies for this story:

### Peter Kruty wrote: Yay :)

I played this already sime time ago and IIRC I was somewhere like 43 level. It is really funny and addictive :) and looong.

### brekeke wrote: bleee

Dyť je to blbý jak necky. Hned první otázka "kolik děr má polo" má minimálně 3 správné odpovědi, a oni uznávají jen jednu... dál jsem to nehrál, je to fakt jen ztráta času.

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## Spam Volume Decline

This month was the first in at least last two years when I had less than 10,000 spam messages per month.

In the above graph there is a number of messages which ended in my spambox per month since January 2006 (which is the first bar) to September 2007 (which is the bar number 21).

The peak was in the last December, when I had 113,477 spam messages. Since then we have deployed greylisting on most systems (the last one around March 2007), but nevertheless, the volume of spam has been decreasing even after that time. Can anybody explain this? Is spam becoming too expensive for spammers?

I don't have a hard data, but it looks like the other people in our domain have a similar decrease in spam volume like me.

## 2 replies for this story:

### Vasek Stodulka wrote:

It seems to be true. I do not have so big jump, but my mailbox at gmail now displays 1200 SPAM messages, I used to have around 1500 last few months.

### Tomas wrote:

Maybe it has something to do with this : http://it.slashdot.org/it/07/10/11/2157244.shtml

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## Tree in a Pot: Part Two

It has been almost two years since I bought my first bonsai tree. It was Serissa foetida ("A Tree of a Thousand Stars"). Looking back at this time I am quite surprised that I am still as interested in bonsai as I was two years ago.

As you can see, my Serissa is still alive :-). It has grown up a bit, so I have decided to grow another level of branches - I have removed most of the apic, keeping only two main branches of the original apic, and another one which I plan to use as a new apic.

The tree has grown many flowers in the last month or so (probably in response to heavier pruning in the apic).

Serissa is not hard to maintain, but it requires a lot of time - without monthly (or tri-weekly) backpruning the apical growth makes the tree proportions out of balance, and (even though I keep my Serissa near the southern window) leafs get more than twice as big on the unpruned twigs than on the backpruned ones.

## 1 replies for this story:

### Peter Kruty wrote: Wow!

I'm really impressed by the first picture. Nice plant, can you make a picture to be link to a larger version, please?

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## Bicycle Rim

A while ago I wrote about my trouble with a new paint for my bicycle frame. I have already solved this problem (people at Aluservis have removed the old paint, and the paintshop Pavel Oršula painted the frame). Today I want to add another complaint to RockRoad.CZ, a shop which did the original paint, and some other repairs of my bicycle:

I bought a new rim for my front wheel there. I used to have 20-622 tyre, and they recommended a suitable new rim, which I have bought. However, yesterday I rode the bicycle and had a quite serious puncture (destroying not only the tube, but also the tyre). I went to another repair shop, which is near to the place where I work, to buy a new tyre and tube. They were quite unhappy with my new rim, and said that 20 milimeters wide tyre is too narrow for this rim, and that they are not surprised that I had a puncture with such a narrow tyre on that relatively wide rim.

So I bought a 23-622 tyre instead (they said even this is probably too narrow for that rim). Meanwhile, I have discovered a new development in bicycle tyres: the new tyre has beads with kevlar cords, which is not only lighter than the tyre with steel cords, but the tyre can also be folded to a small package(!) - just like the inner tube is folded to a small package. Anyway, stay away from RockRoad.CZ.

## 3 replies for this story:

### davro wrote:

Yes, most road cyclists use 23/622. And to add some info about new painting to your bike, I have heart about Boss Opportunity - Brno Líšeň, which has a very good reference. It is a car repair but they do also airbrushing.

### Yenya wrote: Boss

Actually, I have visited Boss in Renault Líšeň. They had longer delivery times (two or three weeks), and they were not willing to remove the old paint. OTOH Pavel Oršula was quite helpful with finding the firm which could remove the old paint. Interestingly enough, one of the images in Boss' galery was the same like Pavel Oršula has shown to me as a sample of his work: http://www.autolakovnaboss.cz/galerie/kola/big/03.jpg

### davro wrote:

hmmm, very nice...

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