Older blog entries for dangermaus (starting at number 45)

31 Dec 2010 (updated 28 Jan 2011 at 09:31 UTC) »

arxiv Droid is my favourite Android app to see science progress. I like the 'Astrophysics All' and 'Computer Science All' categories where the latest papers on those topics are submitted. It is cool to see papers on exoplanets, gravitational anomalies and crazy algorithms costantly flowing :-)

New sync algo for deltasql

Wednesday of last week I had a WebEx session with three people in a company in India who are actively using deltasql. For me it was 7pm, for them it was 10:30pm, and they still were in the office! For me it was a honour that they waited so long to speak with me. Also strange that with India I have three a half hours time shift. I never hard of half an hour time shifts before.

The company they work for does software for hospitals in India and the US, and has as an inspiration a spiritual leader named Mata Amritanandamayi or Amma for friends, and she has many. Among big hospital in India, their company serves also an hospital of a nuclear facility.

The software they ship is a J2EE/mySQL framework based on Jboss, roughly the same architecture used in the company I was previously working for. Being all technology based on Open Source software, for them it was natural to use deltasql to manage the burden of keeping database schemas in sync. The deltasql server was customized with Amma's face and had 2070 scripts in it when they showed it to me in the Webex session.

Their software has a complex history of branching and the source code is managed by Subversion. They pointed out, that in deltasql the information from which a branch is originating is missing, which was the real reason why SQL synchronization on branches of branches never worked. The change in datamodel and the changes in the synchronization algorithm scared me first, beside the fact that I want to keep focus on the GPU project, which at the moment undergoes a full rewrite. Therefore I stated: I will think about it, maybe for end of 2011...

One and a half week later deltasql version 1.3.0 is published: it has a brand new synchronization algorithm which is implemented as a tree traversal from leaf to root recording each segment, and a tree traversal back from root to leaf generating the synchronization scripts for each segment. The final step collates the scripts generated in each segment and presents them to the user. Documentation and FAQs are updated as well.

Starwars ASCII

To complete the underground trip in the last blog entry, the ASCII movie of Star wars:

telnet towel.blinkenlights.nl
30 Oct 2010 (updated 30 Oct 2010 at 08:17 UTC) »

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
READ ...

To disconnect, follow this sequence:


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

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 ...
... 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  

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 ;-)

I found the Underground book of wikileaks founder online in text format. Cool!

Volcano Eyjafjallajoekull

I finished coding the climate simulation frontend for the GPU project. It has some neat features like ashes of Volcano Eyjafjallajoekull which in fact cover Europe during Summer and CO2 cycle based on population density data of U.N. The nuclear war feature still needs some improvements, though.

The atmospheric model is quite simple and do not now if it can stand scientific simulations. The frontend has plenty of parameters which affect the simulation. Inverting earth rotation will also invert coriolis effect on winds, for example. It is possible to put Earth in Mercury or Iupiter orbit and see what happens. Go stop earth rotation or revolution around Sun, or change water density!

To test the climate simulation, it is suggested to download GPU and upgrade it via menu point "Tools->Autoupdate to latest version".

This frontend is completely written in Lazarus/Freepascal. To me, it looks like the Lazarus project is close to production stage, and it is even more powerful than Delphi itself.

ASURO robot

I had a chance to play with the Asuro robot. It was my first experience with the 8bit Atmel ATmega8L microprocessor. Until now I only looked at the PICs microprocessor family without doing anything concrete with it.

One thing to know about ASURO is the behaviour of the PollSwitch() function. The switch sensors return unreliable data. In forums, it is possible to read that only if PollSwitch() returns several times the same value, this value is reliable. Therefore our C-code changed like this:

unsigned char test1, test2, test3, test4;

while (1) {

test1 = PollSwitch(); // retrieve data from LED test2 = PollSwitch(); // retrieve data from odometric sensors test3 = PollSwitch(); // do some more logic test4 = PollSwitch();

if ((test1==test2) && (test2==test3) && (test3==test4)) { if (test1>0) { // at least one of the six sensors is colliding with an object } else { // no collision }


In case the code mentioned above does not work, than try this piece of code we found on the net by hai1991. The code checks if resistors in front of the switches are soldered correctly. Pressing the switches lights LED lamps in a funny way.

#include "asuro.h"
unsigned char taste;
int main(void)

Init(); while(1) { do { taste = PollSwitch(); } while( taste != PollSwitch());

switch(taste) { case 1: StatusLED (GREEN); break; case 2: StatusLED (RED); break; case 4: FrontLED (ON); break; case 8: BackLED (OFF,ON); break; case 16: BackLED (ON,OFF); break; case 32: BackLED (ON,ON); break; default: StatusLED(OFF); BackLED(OFF,OFF); FrontLED(OFF); break; } }

return 0; }


About one year ago, Virginia and me hided this geocache called Lago di Poschiavo close to where we live. Until now it was found 36 times. I wonder if Martina (now 7 months old) will like Geochache. I asked her, she answered me with "ta ta ta", but I am not sure of what it means :-)

23 Jun 2010 (updated 23 Jun 2010 at 14:23 UTC) »
Texturing a sphere in OpenGL?

I am writing a simple climate simulation which will be released soon as frontend for the Global Processing unit project.

One of the tasks is about plotting the Earth in OpenGL, for this I have bitmaps with continents, clouds, temperatures, etc, which I would like to project on the sphere.

I read through documentation on how to texture a sphere. After a while, I decide to go for this approach instead (in Freepascal, which is a phantastic Open source substitute for Delphi):

I create first a "sphere grid" in an array called sphere3d:

procedure init3DGrid(var w : TWorld; var clima : TClima);
var i, j : Longint;
    p1   :T3DPoint;
    lat, lon, altitude : Extended;
 for j := 0 to 179 do
     for i := 0 to 359 do
         lat := YtoLat(j);       //-90..+90
         lon := XtoLon(i);       //-180..+180
         lat := lat/90 * Pi/2 + Pi/2; //0..180
         lon := lon/180 * Pi + Pi;  //0..360
// adding half a degree to longitude for triangles
// in each second row
         if (j mod 2 = 0) then
               lon := lon + 1/720 * 2 * Pi;
         p1.x := - radius * sin(lat) * cos(lon);
         p1.z :=   radius * sin(lat) * sin(lon);
         p1.y := - radius * cos(lat);
         sphere3D[i][j] := p1;

function XtoLon(x : Longint) : Double; begin if (x<0) or (x > 359) then raise Exception.create('x on array has to be between 0 and 359 but was '+IntToStr(x)); Result := x - 180; end;

function YtoLat(y : Longint) : Double; begin if (y<0) or (y > 180) then raise Exception.create('y on array has to be between 0 and 180 but was '+IntToStr(y)); Result := 90 - y; end;

And in the Paint method of my extended TOpenGLControl I do a call to plot3d with my color bitmap and the vertex array computed in the previous procedure Init3dgrid:

procedure plot3d(vertex : P3DGrid; colors : PGridColor);
var i, j,
    target_j : Longint;
    p1,p2,p3,p4 : T3DPoint;
    r, g, b : Extended;
  for j := 0 to 179 do
     for i := 0 to 359 do
          target_i := i+1;
          target_j := j+1;
          if (target_i>359) then target_i := target_i-359;
          if (target_j>179) then target_j := target_j-179;
          p1 := vertex^[i]  [j];
          p2 := vertex^[target_i][j];
          p3 := vertex^[i][target_j];
          p4 := vertex^[target_i][target_j];
          r := Red(colors^[i][j])/255;
          g := Green(colors^[i][j])/255;
          b := Blue(colors^[i][j])/255;
          glVertex3f( p1.x, p1.y, p1.z);              
          glVertex3f( p2.x, p2.y, p2.z);              
          glVertex3f( p3.x, p3.y, p3.z);              
          glVertex3f( p2.x, p2.y, p2.z);              
          glVertex3f( p3.x, p3.y, p3.z);              
          glVertex3f( p4.x, p4.y, p4.z);              

For my limited knowledge of OpenGL, this is easier to setup (and for me to understand) than loading a texture and using a cubic or cilindric projection on a sphere. The performance of this solution is also acceptable, at least for my Earth surface with 129600 (360x180*2) triangles.

On Monday, February 10, I was for working reasons in Milan. In the evening, I randomly walked around the city (following a M sign, thinking it was Mc Donalds, but it was M like Metropolitana, the tube). Close to the Duomo, I read a sign about a conference on micro credit made by Professor Yunus and I remembered reading an article about micro credit in some newspaper (maybe La Repubblica?) ...

I searched for 5 minutes on the map to locate "Teatro dal Verme" where the conference was scheduled and rushed to Castello Sforzesco. In front of the theater there was plenty of police. As I was a little bit late, I decided for the strategy "walk through as you would know where you are headed", because I am equipped with a Swiss army knife and I did not want to be searched and loose the knife and precious time.

The entry was free, I came at the top of the stairs of a huge theater and was very happy to see that what was happening on the stage was projected on the wall, too.

A young girl, Erica Mu, played her song with a guitar using a technique which remembered me of an oscillator where the signal is reinforced by a resonating channel. Then, Paola Turci played her song "Rwanda" which is never broadcasted on the radio, unfortunately. And Paola is a famous Italian singer, too.

A world without poverty

Professor Yunus came on the stage followed by a train of photographers, and explained the principles of micro credit with these words.

"I looked at how a conventional bank works" - he said - " and I did exactly the opposite!" He explained: "First, a conventional bank lends only to rich people, and the richer the more they lend. We lend to the poor people, the poorer, the more we lend. Secondly, a conventional bank lend to men. We lend to women :-)"

He then added "Conventional banks build their buildings in the center of the city, we build our banks in the villages, not in the cities. Customers have to go to the bank, we go to our customers. And conventional banks lend huge amounts of money, we lend only little amounts".

He then recalled a poor woman who received from Yunus 30$ as a credit. She was trembling as she never had touched money in her life. So, she kindly denied, but Yunus insured her that she would pay back only if the eggs of the hen she would buy would give her some kind of return. Yunus soon learned that poor people are honest, they pay back if only they can! (Ehm, just by side as my humble remark: can we say the same of very rich people when they generously decide about their own bonus?)

These principles were the spark to build the Grameen bank, which is a micro credit foundation that helped many Bangladesh people to come out of poverty. With many, we say more than 100 million.

Another fundamental thought in Yunus is that being poor does not mean at all being stupid or less in any way than someone who is rich. In the speech he explained that he was delighted when he met the daughter of a poor woman which had nothing, who managed to become a physician respected by the whole village. Everyone is intelligent and can come out of poverty, if the system does not prevent him to do so.

He extended the concept of micro credit to education and helped students in funding their studies. However, when students finished their education, they came to him and said: "Yunus, unfortunately, there are no jobs where I could apply what I hardly learned!". Yunus explained them, that they should not stand up each morning and think about job seeking, they are powerful enough to think about job giving, to create companies and to create jobs.

In particular, if a student had a good idea, Yunus encouraged him to leave the study and establish his own company. A diploma is a mere piece of paper which gets meaningless if there are no jobs in the economy.

In one of his experiments which keeps running, professor Yunus gave beggars small useful things (like lighters and similar) and asked them instead of begging on the same place, to walk house by house and try to sell these things. Yunus feared beggars did not feel motivated, but he was wrong: they were very happy to act as traveling salesmen. Yunus allowed them to beg in case they were not able to sell anything.

"Funnily enough, as time went by, beggars knew exactly which houses were good to sell things, and which ones were good to beg. Even if they did not own a master degree at Harvard, beggars understood the concept of market segmentation very well!", he added.

In his talk, Yunus criticized the neo-liberal thinking and questioned the principle that being selfish makes everyone richer. This attitude is one of the reasons of the current financial crisis. Yunus believes that being selfish is fine and is related to the instinct of conservation, but it does not have to become a reason of life. Everyone likes to help others and gains positive feelings about it.

In this sense, he called big companies to "social responsibility". With Danone, he created a particular cheap yogurt and marketed it in Bangladesh. A little child that eats for several months this yogurt will not suffer of some of the diseases created by malnutrition. With Adidas, he tries to sell cheap shoes that prevent people to go round barefoot and catch other diseases. These are challenges were profit is not the focus, the focus is something like "create a good cheap shoe for less than 1$". And of course, the image of such responsible companies help them in the conventional economy.

Professor Yunus looks very young for his age, he is 70! And he keeps creating this kind of positive powerful never ending cycles :-)

Finally, an example to say how real the thing might get: I got as a gift for my little child born at the beginning of January a band to carry her around. On the package containing the band, there was a little round stick saying "Grameen Foundation".

Einstein radically upset the way scientists looked at physics, Yunus will radically change the way we understand micro and macroeconomics.

More on Professor Yunus can be found on wikipedia at http://en.wikipedia.org/wiki/Muhammad_Yunus

One solution to escape the cage of firewalls around you and reach your beloved server is

Install Ajaxterm on Gentoo

These are the steps I followed, they should complement the explanation of the wiki of Ajaxterm, created by Antony Lesuisse.

1. setup a Dyndns account and ddclient

Publish the IP address of your router first with these steps:

Visit Dyndns, register an account and your host. Choose a freely available DNS name like delta.dyndns.org. On your Gentoo box, install ddclient

USE="ssl" emerge ddclient
vi /etc/ddclient/ddclient.conf

In ddclient.conf enter your account details for Dyndns.

Launch and register ddclient with

/etc/init.d/ddclient start
rc-update add ddclient default

2. install Ajaxterm

ACCEPT_KEYWORDS="~x86" emerge ajaxterm
/etc/init.d/ajaxterm start

If launching ajaxterm fails with [!!], do the following:

vi /etc/services

At the bottom of the file services add

ajaxterm     8022/tcp
ajaxterm     8022/udp

If launching ajaxterm still fails with [!!], in /etc/init.d/ajaxterm, change the DAEMON variable to /usr/bin/python2.5.

Once ajaxterm starts with a green [OK], point a Javascript enabled browser (the text based links or lynx do not work!) to http://localhost:8022/. If your Gentoo box does not have Gnome or KDE on it, you can also point a browser on the same network segment, e.g. to Ajaxterm will welcome you with the login window :-).

It's time to register ajaxterm to the default runlevel with

rc-update add ajaxterm default
so that it survives reboot...

3. Emerge and configure Apache

In the wiki of Ajaxterm, it is suggested to use Apache as SSL tunnel to Ajaxterm, this for security reasons.

Let's build an apache with some modules ;-)

echo 'APACHE2_MODULES="authz_host actions alias auth_basic
auth_digest authn_anon authn_dbd authn_dbm authn_default
authn_file authz_dbm authz_default authz_groupfile
authz_host authz_owner authz_user autoindex cache dav dav_fs
dav_lock dbd deflate dir disk_cache env expires ext_filter
file_cache filter headers ident imagemap include info
log_config logio mem_cache mime mime_magic negotiation proxy
proxy_ajp proxy_balancer proxy_connect proxy_http rewrite
setenvif speling status unique_id userdir usertrack
vhost_alias"' >> /etc/make.conf

USE="ssl" emerge -av apache

Make sure that D_PROXY and D_PROXY_HTTP are defined in the apache2 file:

vi /etc/conf.d/apache2

Configure the SSL tunnel with

vi /etc/apache2/vhosts.d/00_default_ssl_vhost.conf
VirtualHost *:443>
       ServerName localhost
       SSLEngine On

ProxyRequests Off <Proxy *> Order deny,allow Allow from all </Proxy> ProxyPass /ajaxterm/ http://localhost:8022/ ProxyPassReverse /ajaxterm/ http://localhost:8022/ </VirtualHost>


Start and register Apache2 with

/etc/init.d/apache2 start
rc-update add apache2 default

4. create a certificate for Apache

Here the steps to create a self-signed certificate are described:

openssl req -new > new.cert.csr
When asked for the CommonName, give the DNS name you chose (e.g. delta.dyndns.org). This is important to make the self-signed certificate valid.

Remove the passphrase with

openssl rsa -in privkey.pem -out new.cert.key

Convert the request into the signed certificate:

openssl x509 -in new.cert.csr -out new.cert.cert -req
-signkey new.cert.key -days 3650

Indicate to apache where to find the signed certificate and the key:

vi /etc/apache2/vhosts.d/00_default_ssl_vhost.conf
SSLCertificateFile /path/to/certs/new.cert.cert
SSLCertificateKeyFile /path/to/certs/new.cert.key

Source for these steps: Apache SSL docs

5. configure NAT on your router

Login to your router, go to the NAT section and forward the port 443 to the server where Ajaxterm is running...

That's all, from a caged environemnt, simply point your browser to a https://delta.dyndns.org/ajaxterm/ and add a certificate exception, as the certificate was self signed and not issued by a CA authority.

Have fun!

People who like quiz like


Cescozen is a game invented by Cesco. If you point your browser to the initial page of the game, you'll encounter very difficult enigmas that wait for a solution (note: the game is in Italian). To answer each quiz, you put the solution on the URL, so that you move one directory down the tree. To me and Virgi, it took about a week investing 2-3 hours each day to get through all levels. Sometimes, the quiz requires that you search something in Google, or you have a satellite image and you need to figure out where it is. Very impressive, amazing game!

People who like quiz like also to follow howto instructions to get

The full Map Stack up and running

I am fascinated by the Open Source technology behind OpenStreetMap, which I believe will soon be succesful as Wikipedia is.

After importing the dump of Switzerland in the old Gentoo server, I showed the result to my father and he gave me another piece of iron to reach the next level of this particular game: it is an IBM with 3.2 GHZ and 1 GB of RAM. I installed Ubuntu Jaunty (9.04) on the server and repeated the PostgreSQL and mapnik install following these howto instructions made by Johnny Dobbins. This tutorial additionally explains how to install the WMS server called ogcserver and how to put a cache in front of it, so that already computed tiles do not need to be recomputed but can just be served directly from disk (or from memcache or even from Amazon S3).

Just some remarks on how the job was done:

Choosing a bounding box

the server has 74 GB of disk, so based on this specs I decided to import Europe and part of Asia till longitude of Moskau and not the whole planet. For the whole planet you probably need at least 200 GB of disk.

To be precise I chose this rectangle with coordinates taken from an old fashioned Atlas: Top left corner: 75 N, 35 W Bottom right corner: 20N 60 E

This command extracted from the whole planet file the bounding box and created a new dump called eurasia.osm.bz2. The decompression and compression is done with bzcat and bzip2 piped together.

bzcat ../../planet-latest.osm.bz2 | ./bin/osmosis --read-xml
enableDateParsing=no file=/dev/stdin --bounding-box left=-35
bottom=20 right=60 top=75 --write-xml file=- | bzip2 >

The execution lasted for about 14 hours. Out of the 7.4 GB of planet-latest.osm.bz2, about 2.2 GB of data where extracted for eurasia.osm.bz2. After the import with osm2pgsql in Postgres database, the bounding box takes about 40 GB of disk space.

Minor remarks on the howto of Johnny

I did not find the lines in cgiserver.py, so I left this step out.

For the file wms.py: you need to completely replace the existing file with the lines shown in the howto.

Setup of ogcserver

When browsing to http://localhost:8080, I got an error. Looking at /var/log/apache2/error.log,

I noticed this error:

IOError: sys.stdin access restricted by mod_wsgi           

I then added at the bottom of /etc/apache2/sites-available/default outside the VirtualHost section the following two lines:

WSGIRestrictStdout Off
WSGIRestrictStdin Off

Tilecache: Seeding the cache

After setting everything up, pieces of the map started appearing. However, often the server got overloaded, if it had to compute tiles which where full of features (streets and rivers). Especially the tile with Germany never appeared as it was too feature rich. Eventually, the server hang up when even the swap cache got full.

The solution to this performance problem was to seed the cache. I chose a point in the center of Europe (46 N, 10 E) and a radius of 30 degrees.

I then issued in the directory ogcserver/tilecache-2.10/ the following command:

./tilecache_seed.py basic
[press Control D on the keyboard]

and I let compute map tiles for about 48 hours.

The result

Here it is :-). Happy browsing, press twice the plus button first, to reach the correct zoom level. The speed in serving tiles might vary, as I have an ADSL and use dynamic DNS...

11 Dec 2009 (updated 11 Dec 2009 at 13:29 UTC) »

I managed to install Openstreetmap on Gentoo (status: December 2009) and I could generate some interesting tiles of Poschiavo, which is a little valley in the mountains where I live. My server is an AMD k6-600 MHZ with 600 MB of RAM, so not a real power horse but quite an old scrap iron thing. Of course, I did not import the whole planet, but only a dump of Switzerland.

Your own Openstreet map tile server on Gentoo

I wrote down some steps that differ from the excellent tutorials here and here, because my installation is performed on Gentoo instead of Ubuntu: of course, this is working now as for December 2009, but an emerge --sync in the future might solve some of these problematic steps (maybe someone more knowledgeable than me will read this tutorial and fix some ebuilds :-).

Step: Subversion and Java

These one were easy and you probably figured out faster than me: emerge -av subversion
emerge -av sun-jdk

Step: Installing Postgresql with Postigs spatial extensions

osm2pgsql does not work with Postgresql 8.1 which is marked stable in Gentoo. The reason is that Postgresql 8.1.11 does not know about the command 'DROP TABLE IF EXISTS' which is used in oms2pgsql. Defining a stored procedure that does the same and modifying the source code of osm2pgsql did not work for me.

Therefore I chose another way, which goes as follows: you should add at the end of /root/.bashrc the following alias:

alias aemerge='ACCEPT_KEYWORDS="~x86" emerge '
source /root/.bashrc will load this setting for the first time. The setting is kept after, as .bashrc is read at every login. From now on, you can use "aemerge" to emerge unstable packages instead of "emerge".

Then, you can install an unstable Postgresql with
aemerge -av postgresql

This will install a Postgresql 8.2.14 which is fine for our purposes.

Install also Postgis:
aemerge -av postgis
Postgis-1.4.0 is then installed.

Configure the database postgis extensions not by using emerge --config as suggested at the end of emerge, but use the instructions provided in this tutorial. Remember to follow the instructions as normal user and not as superuser (a part of the inital step of setting up the database).

As noted in the previous comment, lwpostgresql.sql does not exist in postgis anymore, it was renamed in postgis.sql, you should therefore use
psql -d gis -f /usr/share/postgresql/contrib/postgis.sql

Step: Installing mapnik
For mapnik I had problems, it did not compile from source as described in the tutorial, it was failing when compiling the postgis plugin for linking reasons against the library libpq.la, though the library was present on the proposed path.

I did the following trick:

USE="postgresql" aemerge -av mapnik

emerged and installed a mapnik with all dependencies, which however was not able to recognize the postgis extensions on the 'gis' database.

In fact, when running ./z0_generate_tiles.py, mapnik was failing with:

Could not create datasource. No plugin found for type 'postgis' (encountered during parsing of layer 'leisure') when connecting to the imported database.

Then I did the following: I unmerged the unstable libpq library (libpq is a library used by postgresql used as connection layer.
emerge --unmerge libpq
I unmerged mapnik without its dependencies with
emerge --unmerge mapnik
I installed the stable libpq library with:
emerge -av libpq
Then I installed mapnik from source with the following steps
mkdir src
cd src
svn co http://svn.mapnik.org/trunk/ mapnik
cd mapnik
scons/scons.py -c install
scons/scons.py PGSQL_LIBS=/usr/lib/postgresql/ PGSQL_INCLUDES=/usr/include/postgresql/
sudo scons/scons.py install PGSQL_LIBS=/usr/lib/postgresql/ PGSQL_INCLUDES=/usr/include/postgresql/

Therefore: postgresql is compiled against an unstable version of libpq, while mapnik needs a stable one to compile. Of course, postgresql will survive the restart with
/etc/init.d/postgresql restart

Have fun with your maps! Import the planet on your favourite Gentoo box!

I was browsing through the apache logs with cat /var/log/apache2/access_log and I wondered how many crawlerbots are visiting our webserver... No wonder that the visitor counts are always showing way too many visitors :-D

Coffee Break Planner

To increase the number of visitors to our webserver, I finally found a killer application. I developed it as a Google Gadget and is called the Coffee Break Planner. This gadget helps you to meet with your friends at the right time for a tasteful coffee... It also increases the overall performance of your company, as in coffee breaks most of the time people speak about work anyway :-)

Again, the gadget is only an xml envelope, while PHP and mySQL do the hard work.

Webserver Gate Gadget

I created this gadget to upload files to my webserver as ftp is firewalled in the company I am working for. I prepared it so that other people can install on their webserver as well, if they read the Readme on the gadget :-)

To work on the webserver I use this service, which costed me 15 euro for one year. It is a Unix shell via HTTPS that can be opened with a normal browser. Tunneling with httptunnel or corkscrew or any other trick did not work for me... Too stupid to break out without commercial support, ehm!


Since beginning of the year I manage the local boy scout homepage with Joomla and I am very happy with this solution, last but not least released as Open Source.

Android emulator v2.0

I am experimenting with Eclipse, Android v2.0 and a tutorial a friend did... But I still do not have meaningful results. Some Java exception crashes the small application and the emulator does not work behind the proxy, even if the -http-proxy option is set in the launch parameters. Notice that the mysql trick works only with Android 1.6. Probably the proxy filters also on the browser identification string... and the emulator does not mimic a Mozilla or IE as identification... And the proxy is difficult to overcome...

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