creating fractals in javascript

Just found out about the Context Free Art project through it’s javascript port, ContextFree.js done by Aza Raskin, the same guy involved in the development of Firefox. Raskin developed a lovely playful site, Algorithm Ink. I actually showed it to a friend who’s not a developer and she started playing right away : )

Here’s an example: http://azarask.in/projects/algorithm-ink/#aa486456 . Click browse to see lots more.

how to install munin on rhel

Just jotting down all the steps I took to install Munin on a RHEL server:

1. Login as root
2. Add the Epel Repository
   $ sudo rpm -Uvh http://download.fedora.redhat.com/pub/epel/5/i386/epel-release-5-3.noarch.rpm
3. $ sudo yum install munin munin-node
   Dont forget to say yes on all checks. I got distracted by the phone and when I looked again I had a missing dependency error.
4. Edit munin’s conf file
   $ vim /etc/munin/munin.conf
5. Set up mail alerts when a status change occurs (eg from OK to warning)
   contact.sofia.command mail -s “Munin notification” sofia@example.com
6. Notice the line
   # htmldir /var/www/html/munin
   This will set where munin’s reports will beaccessible by the web browser. Change it (and uncomment it) if you want but make sure the folder you set it is writable by munin (chown -R munin <directory>). I had some problems here, Munin didnt create the files there so i set up an alias. But maybe you’ll be fine : )
7. Write and close munin.conf. Edit munin-node
   $ vim /etc/munin/munin-node.conf
8. Change the host entry from
   host *
   to
   host 127.0.0.1
   In this way you restrict the node to listen to localhost only
9. Start munin
   $ sudo /etc/init.d/munin-node start
10. Add munin to reboot
    $ sudo /sbin/chkconfig munin-node on
11. Set up the alias. My public directory isnt there so I needed to set up an alias in httpd.conf
    $ vim /etc/httpd/conf/httpd.conf
12. Add the below at the end adjusting what you need

    Alias /srvmunin /var/www/html/munin
    <Directory /var/www/html/munin>
        Options FollowSymLinks
        AllowOverride None
        Order allow,deny
        Allow from all
    
        AuthType Basic
        AuthName "Members Only"
        AuthUserFile /etc/munin/munin-htpasswd
        <limit GET PUT POST>
        Require user admin
        </limit>

    </Directory>

    Notice we set the alias at srvmunin, so that the reports will be viewable at www.example.com/srvmunin. We also set an httpauth because otherwise anyone can see the munin reports.

13. Write and close and restart apache
    $ /sbin/service httpd stop
    $ /sbin/service httpd start
    Someone told me this was quicker than a restart (service httpd restart) but I have no idea if it’s true
14. Set up the password
    $ htpasswd -c /etc/munin/munin-htpasswd admin
15. Go to www.example.com/srvmunin and you should be prompted for the password. Then wait a few hours and you’ll start to see the charts. Done!

This was heavily taken from slicehost’s article on munin so if anything goes wrong check there as well.

NLP e Língua Portuguesa

Desde há algum tempo que tenho alguma curiosidade sobre NLP (natural language processing) tanto a nível teórico (como funcionam os algoritmos que usam) como a nivel prático. Não existe por exemplo, um serviço semelhante ao Apture para português. Assim, derivados das minhas pesquisas aqui vão alguns links que achei interessantes:

LXSuite - um conjunto de webservices para a análise linguística de texto desenvolvido pela Universidade Lisboa. Na LxSuite estão todos juntos mas podem ser vistos em separado no LxCenter. Infelizmente, o serviço não tem api e é necessário consentimento para o seu uso.

LXService:  Web Services of Language Technology for Portuguese - artigo a descrever o desenvolvimento dos webservices acima.

Linguateca - todo um conjunto de recursos de NLP para a língua portuguesa. O HAREM - NER for portuguese e respectivo livro está aqui. Eles também disponibilizam vários corpus para português aqui, inclusivé o CETEMPúblico (disponível para download gratuitamente).

Portuguese Language Processing Service - um artigo sobre o desenvolvimento dum conjunto de webservices de NLP para língua portuguesa desenvolvido no Brasil. De acordo com os próprios:

In this paper, we describe F-EXT-WS, a Portuguese Language Processing Service that is now available at the Web. The first version of this service provides Part-of-Speech Tagging, Noun Phrase Chunking and Named Entity Recognition. All these tools were built with the Entropy Guided Transformation Learning algorithm, a state-of-the-art Machine Learning algorithm for such tasks.

Este artigo parece interessante e pode ser um ponto de partida para outras explorações (ex. ETL/Entropy Guided Transformation Learning - ver Portuguese corpus-based learning using ETL). Fui ver o F-EXT-WS mas é necessário registo e deu erro.

Alguém conhece outros recursos interessantes dentro desta àrea?

Sixth Sense

This is truly amazing..

And another interesting find: LED tattoos

Links on tdd, css & others

• Doctest - runnable tests inside the docstrings (php pear package)
• Mutation testing 
  

  “Mutation Testing is basically testing…for tests. It ensures that your tests are truly capable of detecting errors and problems with the source code. It does this by mutating the source code itself (using ext/runkit) in such a way that an error is created in the code. If your tests detect the error, all is well with the world. If your tests do not detect the error…well, you better add a new test that does” 

• Phpcp
  

  “phpcpd is a Copy/Paste Detector (CPD) for PHP code.

  The goal of phpcpd is not not to replace more sophisticated tools such as phpcs, pdepend, or phpmd, but rather to provide an alternative to them when you just need to get a quick overview of duplicated code in a project.”

• Object oriented CSS
  

  “OOCSS allows you to write fast, maintainable, standards-based front end code.” 

• Bespin
  

  Bespin is a Mozilla Labs experiment on how to build an extensible Web code editor using HTML 5 technology.

Doctests for php - test & create documentation

Recently I found out about doctests in php. Doctests are tests you can put inside the docblock of the class or method. They originated in python but now there’s a ruby implementation, a php implementation and even a javascript implementation. 

An example will explain better (applies to the php package):

class simplemath

{

/**
* subtract function.
*
* @access public
* @param int $a
* @param int $b
* @return int
*
* <code>
* //doctest: subtract
* echo simplemath::subtract(10,6);
* //expects:
* //4
* </code>
*/
public static function subtract($a, $b)
{
return (int)$a - (int)$b;
}


}

The test itself is inside the <code> tags. If I then run this code through doctest’s commandline runner for php, by running

$ phpdt simplemath.php

I’ll get something like this:

Doctests can serve as great documentation by example and as tests, both for your documentation - comments tend to get terribly out of date (when code changes the comments aren’t updated accordingly) - and for the code itself.

I’ve also found they’re an invaluable tool during development. Imagine you’re developing a method that validates credit card numbers and the only way to get to it in a browser is to perform several actions, eg going to the specific webpage, inputting the credit card number, and submitting the form - it’s hell basically. If you’re already doing TDD and using phpUnit you’re probably not doing this but doctest for me has an advantage there, the test and the code being tested are in the same file - it’s all there! and so it’s really easy to grasp the problem at hand.

My process has been,

• write a test case in doctest
• write the code itself
• test
• repeat as necessary

Due to this I submitted a patch to allow the testing of only 1 test, it’s not in the current release but it’s been accepted. This way instead of waiting for all the tests to run, i can run only the method I’m working on.

Another cool thing about it is you become aware of any initial setup code and dependencies. Look at the following:


 /**
* Calculates the number of nights between the start and end date of the booking
* @return int
*

* <code>
* // doctest: booker->total_nights
* require_once('lib/utilities.class.php');
* $booker = new booker();
* $booker->startDate = '2009-02-23';
* $booker->endDate = '2009-02-26';
* echo $booker->total_nights(). "\n";
* // expects:
* // 3
* </code>
*
*/
public function total_nights()
{
if (!isset($this->startDate) || !isset($this->endDate)) {
return false;
}
return (int)utilities::date_diff($this->startDate,$this->endDate,'d');
}