chris blogs: March 2004

31mar2004 · rival

Tonight, I had a great idea on how to debug running ruby applications: One simply needs to write a kind of irb clone to run on a specifc port which it can be accessed at.

By telnetting to that port, one then can execute arbitrary commands in the scope of the running program. It should be even possible to reload large parts of the application, at runtime.

Currently I have been too busy to start any coding on it—I call it rival, ruby interactive evaluator. I hope to start development tomorrow or maybe even this evening.

NP: Beatsteaks—To be strong

31mar2004 · Stilblüten today

Jaja, Lehrer:

Du kriegst jetzt gleich ein auf den Kopp, du Arsch!

Jetzt leckscht mi' am Arsch!

Dann wurden noch einige Schülerinnen mit Mineralwasser bespritzt.

Frau Fehse, darf ich 'nen Backstein runterwerfen?

Aber das hat nix damit zu tun, dass man Schwäbisch schreiben muss—das dialektisch?

Wie heißt ihr Friseur? — Du siehst aber auch nicht besser aus, oder?

We have joints, we have fun, we have seasons in the sun...

30mar2004 · SBCL 0.8.9

Yay,

 The build seems to have finished successfully,
 including      13 (out of      13) contributed
 modules.  If you would like to run
 more extensive tests on the new SBCL, you can try
   cd tests && sh ./run-tests.sh
 (but expect some failures on non-x86 platforms).
 Tue Mar 30 14:34:29 CEST 2004

 real    30m22.079s
 user    26m12.300s
 sys     1m24.010s

 //apparent success (reached end of
 run-tests.sh normally)

Finally a up-to-date Lisp on my box. :-)

Somehow slate now builds much faster than it did before.

30mar2004 · Spass in der Schule

Irgendwie war heute ein sehr witziger Tag in der Schule. Paar Zitate:

Im Sommer ist doch immer irgendwas in der Staatsgallerie.—Ja, heiß!

Wusstet ihr, dass der Weihnachtskeksbäcker seine Konkurrenten ausstechen will?

Die Schweine brauchen 'ne gewisse Zeit bis sie reif sind.

Außerdem wissen wir jetzt, dass Herr Schumms Katze vielleicht die hauseigene Bananenernte anpinkelt...

So gehet hin und hütet eure Körpersäfte!

NP: The Sounds—Living in America

28mar2004 · Comparing operating systems by their email storage formats

Much of the design and philosophy of operating environments can be found out by the file formats they use. In this note, I'll compare the file formats of the default mail programs of Unix, ITS and Windows.

On Unix, I take mail(1) as reference mail program, since many other mail programs use the same file format, mbox, but a look at maildir will also be taken. On ITS, RMail and Babyl are examined. Finally on Windows, Outlook Express is the only mail program included by default.

The mbox format of Unix is very simple: Its a file with a number of RFC (2)822 messages separated by lines like

 From MAILER-DAEMON Tue Dec 17 16:53:03 2002

Lines starting with "From" are taken as message delimiters.

The simplicity of this format speaks for Unix, its very easy to edit and manipulate, to search and retrieve messages of the file.

However, as (unfortunately) so often in Unix, this was not thought to the end: What happens if the message itself contains a "From" line? Here, mbox(5) tells us what to do: In order to avoid misinterpretation of lines in message bodies which begin with the four characters "From", followed by a space character, the character ">" is commonly prepended in front of such lines.

What a ugly hack! And still, no-one tells what to do with lines that start with ">From"... (It is interesting by the way that sometimes you see articles in newspapers that include the word ">From"...)

ITS mainly used two MUAs, RMail and Babyl. Both of them have almost the same structure and are very similar to mbox too. All messages are concatenated as RFC (2)822 messages, but they are separated by ^_ (ASCII 31, octal 037, also known as Unit Separator (US)) on a single line.

This is obviously the right thing: A special character was made for this purpose, so it's used. Furthermore, its a non-printable char and so would be encoded using quoted-printable or MIME even anyway. (At least if that existed back than.) Still, this format has all the good sides of mbox stated as above.

Outlook Express, the default mail program on recent Windows versions, uses magical, binary and proprietary PST files not readable by humans. There exist some tools and special libraries to access these files, the format however is neither open nor portable and not used by any other program (except in input filters). This is the usual way of making a monopoly, first force the users to use something, and later force them say there as they cannot switch (you cannot export your mails into some other format with Outlook Express).

All these formats have something unique, they are all stored in a single file. This can easily cause data corruption, for example if several processes access the same file. While not fatal in the case of mbox and RMail, Outlook Express files are likely to be fubar.

Therefore D. J. Bernstein invented a new way to storage mail, the maildir format. Here, mail is stored in—as the name says—directories. Furthermore, maildir doesn't need locking as two processes can write into the same directory concurrently. This helps a lot as many networked file systems handle locking badly or not at all.

Basically, a maildir directory includes three subdirectories, tmp/, new/ and cur/. new/ and cur/ have exactly the same substructure—except that new/ contains unread mail and cur/ mail already seen my the MUA—as they contain files with the single messages in RFC (2)822 format without any content escaping at all.

maildir is available for and being used on many Unixes and clones, including GNU/Linux and various BSD.

It is truly is the best format of them and without any hacks at all, still being open, independent and easy to use. In fact, a user could read his mail without any MUA at all, using only the standard file utilities found on any system.

So, what can you learn of this comparison?

Looking at how elementary things are done, you learn a lot about how the rest of the stuff works. You immediately see if its closed, complex and opaque (Windows), or open, simple, flexible but not always well-thought (Unix) or open, simple, flexible, and done as best as possible (ITS, please note that ITS didn't support nested directories, so maildir wasn't possible way back then).

And sometimes, there's a new technology which is different, but better than everything before. Then go ahead and use it, and drop the old things, but keep compatibility to them (there is maildir2mbox), at least at much as possible and as long as its reasonable.

NP: The Overprivileged—Power Shift

27mar2004 · Kurt Cobain Jokes

I just found these great Kurt Cobain jokes on the c2 wiki:

Did you hear Kurt Cobain was on the TV?
— ...and on the carpet, the walls, the furniture...

What was Kurt Cobain's last hit? — The floor.

More at http://c2.com/cgi/wiki?KurtCobainJokes.

27mar2004 · Zork on ITS

Today, I tried running Zork on my ITS emulation: (fixed line breaking due limited line length)

 *:zork
   There appears before you a huge figure
 clothed in a dark robe. As you shrink back
 in awe, he speaks:
 
    ``This is not the machine
      of the Zork Implementors!''
 
 Then, as suddenly as it appeared, his
 image dissolves, leaving you in darkness.
 
 As your eyes grow more accustomed to
 the dim light, you notice a clue etched
 on the wall... It reads:
 
    No MIT machine supports Zork any longer.
    Questions may be directed to ZORK@DM.
         FMZC, GUE 745
 
 Beneath this message a passerby has scrawled:
 
    No MIT supports DM any longer.
    Save your breath.
         FMGC, GUE 799
 
 >look
 I see no Zork here.
 >n
 I see no Zork here.
 >?
 I see no Zork here.
 Your lamp is growing dim.
 >help
 I see no Zork here.
 Your lamp has run out of light. A hungry grue
 attacks you and rips you to pieces.
 (Next time try Zork on a friendlier system.)
 *:version
 KN ITS.1647. DDT.1545.
 USR:CHRIS HACTRN, TTY 11
 *

:-)

NP: Hammerfall—Legacy of Kings

26mar2004 · PISA

This year I am, just like last year, going to participate at PISA.

PISA, Programme for International Student Assessment, tests the students of different countries in order to compare them against each other.

In 2000, Germany failed miserably (We were the third worst IIRC, Finland was place 1). Various reasons were found, and different new ideas tested. Currently, they are trying do introduce full time schools, which I'm strongly against, but thats another issue.

In 2003, I too participated at the tests. Honestly, they were ridiculous. First, the guy came in and read the instructions off a sheet of paper, "so all students have the same conditions".

Then, we were supposed to do the tests. Every student got a "PISA-pen", bought only for that purpose. We were allowed to keep them at the end.

Back to the tests: Mostly it was maths, which is one of my strengths anyway. There were some questions on text understanding too. I found the questions very easy for the greatest part, and I assume you could do them do.

During the test, we were given about four books of tests with about 70 pages each full of questions.

The last book finally contained the most funny questions, it was about your environment: Do you have a dishwasher at home? A washing machine? Do you use drugs? How long do you watch television per day? Do your parents help you with your homework? Do you think they are good in maths? How about geography?

The best question however was: How often do you watch porn per week? Seriously, after going through all those questions, many students were bored and answered them wrongly just for fun. When they asked "Do you know what a anti-virus-program is?", I answered "No, I run GNU/Linux."

Oh, yeah: The tests were done in May 2003 and they still have—that was a year ago!—no specific results (to us). Go figure.

I'm really looking forward to the tests this year. :-)

NP: Eddie Vedder—The Times They Are a-Changing

26mar2004 · Hello to "chris blogs"!

Welcome to chris blogs, my new weblog.

In here, I'll discuss and comment things happening in my life, recent news, music and code.

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