Advogato: Blog for dangermaus

Martina is now 10 month old and while Virgi is at work on weekends I have to look at her. Fortunately, she is now opening a drawer and reordering its contents (mainly my pijamas), so that I have time to blog this entry! 8-)

git is faster than light

git is really fast, faster than my shadow and faster than cvs. I therefore moved deltasql repository on git and created a new git repository for what will become GPU II.

On gentoo, emerge git will install it. On ubuntu, sudo install apt-get gitcore will do it. On Windows, I use git extensions.

A good introduction to git is on the progit book. There is also a git plugin for eclipse, which I did not test until now.

Continouus database integration with deltasql

I finished the bash client for deltasql server, which can be used for continouus database integration. The bash client included in Release 1.2.0 supports Oracle and mySQL. The next release should support postgreSQL as well. I did an additional effort to document deltasql, trying to explain why there is need of projects and modules and how the synchronization mechanism works.

Going underground...

After reading the book, I went underground for a while, and I discovered these interesting things:

1. Facebook anno 1987

If you want to see how facebook looked like in 1987, telnet to the server mail.encompasserve.org and register an account for free following the given instructions carefully. It's an old but respectful VAX machine (OpenVMS Alpha Operating System). Then go and read the mails in the forum with these commands:


telnet mail.encompasserve.org
NOTES
OPEN WHO_AM_I
READ 4
READ 5
READ 6
READ 7
READ ...

To disconnect, follow this sequence:


exit
exit
disconnect

2. The Rogue game

The precursor of Dungeon and Dragons which was also featured in Scientific American. In the Italian version 'Le Scienze' I found the article for April 1985, edition number 200. I remember playing a version of this game named Moria on MS/DOS, when I was young and healthy 8-).

With this command sequence you can watch people and robots playing the game:


telnet nethack.alt.org
w
a

To exit, press three times 'q' on your keyboard.

3. Retrieving positions from celestial objects from NASA server

Instead of hacking into NASA as suggested by the book, one might enter NASA by its front door. Assume we want to know how far from the Sun the most far thing built by mankind is, then we need to ask HORIZONS.


telnet ssd.jpl.nasa.gov 6775
Pioneer 11
... scroll down until 100% with Enter ...
e
v
500@Sun
y
eclip
2010-Oct-30
2010-Oct-31
1d
y
... scroll down until you see ...
... JDCT  ...
... X  Y  Z
2455499.500000000 = A.D. 2010-Oct-30 00:00:00.0000 (CT)
   1.538965002087235E+01 -7.644892272720375E+01  
1.995301567624495E+01

It means that Pioneer 11 is distant from sun 15.38 AU in X direction, -76.45 AU in Y direction and 19.95 AU in Z direction as of 30 October 2010 (today). Calculating the distance with Pythagoras gives a distance from the Center of the Sun of 80.49 AU. An AU (Astronomical Unit) is defined as the average distance between Earth and Sun, it's about 100 million km. So Pioneer 11 is distant from us 80.49 * 100E6 km, 8.049 billion kilometers!

Sending a signal to Pioneer 11 should take 8049E9 m / (3E8 (m/s)) = 26830 s = 7.45 hours of travel in the empty darkness of space until it reaches the space probe. So as last exercise, execute this command, but you need to wait 2*7.45 hours until you get an answer as the signal needs to travel back:


telnet spaceprobes.jpl.nasa.gov 6775
enable redshift adjust
connect Pioneer 11
echo "hi little green man, please do not touch the 
antenna, thanks!"

Just a joke ;-)

30 Oct 2010 dangermaus » (Journeyer)