Blog.Project13.pl » webmaster

def recent = [python, grails, netbeans platform, hibernate, spring, vaadin, google guava]

Ktoso — Sat, 08 May 2010 20:24:15 +0000

Just an quick summary of what I’ve been coding lately:

http://github.com/barthez/mysql.integra.dbfiller – an simple Python app that is able to generate SQL code with inserts that we need to fill up our database for load testing. It’s doing an simple simulation of people checking in and out from various activities at some job and calculates when who should cone and do their shift… My friend Bartek is by far more into python, and has coded most of this app (just check the impact charts ;-)), so much of the kudos for this goes to him.

Noticed an gigantic hardware problem our student groups server… Some didn’t believe me in the beginning… This week we went to see how much of the harddrives “went bye bye” in real life, as there was nothing that could be done remotely. I’ve been battling with the read-only / filesystem some evenings before, and concluded that it’s not just a small hdd failure – it had to be something BIG… And boy, BIG it was… Something between all the drives and the rest of the server seems to have died. My best guess is the SCSI controller… It’s not really worth it to replace the parts as the server was very very old, well, let’s hope we get some (anything) machine to finally run our tests on. SCSI Controllers on fire…

netbeans.edu.pl – was written by me in Grails. I have yet to release the sources, but will do so for sure – after I polish them a little, because they’ve been written under immense time pressure etc. It’s a quite nice framework, but obviously it’s an overkill for such an simple site as netbeans.edu.pl… It was quite fun to write my own taglib for the twitter integration and also I’ve also used the GoogleData API to serve images directly from Picasa Web Albums… Of course there are PHP lib’s that could do this, but it just seemed “nicer” to me to write this in Groovy…

After the NBPTraining me and two friends started developing an simple Traveling Salesman Visualization using the NetBeans Platform – solving the problem with Genetic Algorithms. We’ve decided to use prefuse for the graph visualization stuff… Let’s hope it was a good decision – of course I know that it’s not being developed since a long time, and the API isn’t even Generic, but it looks quite nice and the workflow with grapghs is really neat – the “actions” stuff… I’ll be trying to write our own renderer for this program so keep your fingers crossed – hope it’s turn out well. Sadly, were presenting an pre-alpha of this program on Wednesday and I won’t be able to come to the uni as at that time I’ll be taking the Gradle Training at GeeCON. :-)

Inspired by both koziołek’s post about vaadin + spring and the nice tutorial that Darek Zoń has been writing lately I decided to take another look at Vaadin. I’d describe it best as… “GWT that looks and feels good right from the start”… ;-) The sources of what might become an simple rss reader app can be found on github: RssR – vaadin rss reader. I’ve had some experience with GWT while trying to create an online crossword solving system, but I have to admit – it’s not really near it’s final stages… And I somehow dont have the willpower to go back to it at this moment – while starting out with it I hoped that I could easily just drop my existing crossword stuff into GWT and add some simple frontend – turned out that this isn’t so easy. Ah well. Vaadin on the other side looks much nicer for some “real, even if generic, webapp”, so I chose to try implementing an simple rssreader based on it. Loging in and basic hibernate setup (not finished yet) is already in place. Oh, and I’m also using maven on this one. If you’re interested in it, or are just abour ti start an Vaadin project, check out the sources and maby they’ll help you out figuring out what all this is about :-) It’s able to run on jetty by calling mvn jetty:run-war :-) (lol just found an google code project about exactly the same stuff only written in pure spring http://code.google.com/p/rsser Kudos to the coder! :-))

Oh and just an minor mention about Google Guava, I’ve been looking at it’s API lately and it’s quite nice I think. It’s not as magic filled as op4j, but this might be just the good thing about it. As I had to do an presentation to pass an class about presentations at school, I’ve done this super simple presentation about a very basic subset of Guava’s features. While doing it I’ve learned how to use the LaTeX Beamer class, and yup, it’s really very nice indeed! Notice the coloured Java syntax? Nice trick, ain’t it :-)

Oh, and while doing all this I also created an very simple website www.kemerling.pl. The graphics where done by another friend of mine. It was quite hell to get all this to display properly (the while part, with bazylion transparent layers… ;-)), but I hope it looks all right :-)

Hmm… back to coding! Gotta improve the NBP Traveling Salesman now :-)

PS: It seems that this blog has been added to www.dworld.pl/blogEntry/blog/113! Whoa that’s really really awesome and I’m really really grateful to be aggregated together with Poland’s most active Java bloggers :-) I don’t know whom I should thank for adding me there, so I’ll thank that the whole community and Grzegorz Duda as dworlds author :-)

OVH’s “main domain” concept

Ktoso — Thu, 08 Apr 2010 13:59:54 +0000

This will be an short explaination about how OVH treats domains/servers (virtual servers) as @pwesolek asked me on twitter to expand about this a little.

What I don’t “like” there is that an server is bound to one special domain that they call the server’s “main domain“. Fair enough, he ought to have some “main” thing right? Basically, the domain is identified 1 to 1 with the server, and this one, has some special stuff it can do. It’s like “I’ll call this server example.com” and then you work with example.com, kinda not caring wtah server it is. And that’s not harmful at all but:

The problem comes up if you host multiple domains – each of which would like to be “mainish” – be able to setup email accounts easily etc.

The part with multiple websites is simple: you set it up using what they call “multidomains” (weird name…) – it’s basically like httpd’s VirtualHost stuff. “Ok, nice.” – you think and then want to setup mail adresses for those domains you’ve hooked up to this server. Should be easy – right? You could just enter some [login]@[domain] and be done with it. But it’s not that simple since all you can do is add emails inside the servers “main domain” (if you’d try to youd get into relay domain denial stuff). You’re forced to buy some sucky (25MB POP accounts) extra “MX pack”… I’ve encountered this while using an domain not registered in OVH, so it’s possible that this is easier with domains bought “from them”, but I doubt it (nothing suggesting this in sight on their website).

To sum it up: You can only easily set up email accounts for an domain that is the servers “main domain” – it’s 2 clicks. Setting the same stuff up for an “not main domain” – will cost you a little extra.

Another weirdity is that if you want to change an servers main domain – it’ll cost you a little (not much).

That said – ovh is an reiable hosting company and does not try to “rob” the user from every penny he’s got like nazwa.pl does on their “WOWOWO FREEEE* domains” – you can guess what for the * there is… ;-) I’ve seen lot’s of hosting operators and ovh is certainly one of the best when it comes to “techy stuff”. I also often recommend (and have used) linuxpl.com it’s also very nice for virtual hosting – I’ve seen an VPS there and it was horrible – many “magical” things were happening there (it was openvz based if I recall propperly) but Virtual Hosting is top class there (svn, python, rails, ssh, synfony, all preinstalled :-))

jQuery tricks 1: automatic-wslider

Ktoso — Fri, 11 Dec 2009 22:19:12 +0000

This time I’ll post some actual code. A client wanted me to write an “image slider”. You’ve probably seen lot’s of them online – and a whole lot of them is in flash – why? There is no need to involve flash in such a trivial task, and jQuery is more than up to the job :-) I used jQuery with the wslide plugin, it’s simple and quite neat. But it does not slide on it’s own. But thanks to it’s simplicity I was able add the functionality I needed in just a few lines of clean code. I used the timer plugin to “click” on the slider at some interval and voila – the birth of an automatic jquery image slider. Anyways, here’s thecode:

var canDo = true;
/** plugin @author: http://www.webinventif.fr/wslide-plugin/ */
$(document).ready(function(){
$('#slidermenu, #slider, .cube').mouseover(function(){
canDo = false;
}).mouseout(function(){
canDo = true;
});
$('#slider').wslide({
width: 900,
height: 200,
pos: 1,
fade: true,
horiz: true,
autolink: 'slidermenu',
speed:300
});
$.timer(5000, function (timer) {
if(canDo){
if($('#slidermenu a:last').hasClass('wactive')){
$('#slidermenu a:first').click();
}else{
$('#slidermenu .wactive').next().click();
}
}
});
});

Terminal Heroes – 1 – mysql backup insert

Ktoso — Sat, 22 Aug 2009 20:39:15 +0000

Just a quick note while dumping a 70MB database… ;-) Let’s say i got my database backup from phpmyadmin, compressed with gz (zip’s also fine), while getting the backup,even if it’s BIG ain’t really a problem, putting it into the database can be troublesome becouse timeout’s etc, especially if it’s a BIG file ;-) My tip here is:

Download the compressed backup
Put it onto your target server, by FTP, SFTP or SCP, doesn’t really matter
Launch SSH and use your terminal hero skillzorz:

cd where/i/put/the/file gunzip backup.sql.gz #or unzip backup.sql.zip mysql-u username -D database_name -pPASSWD < backup.sql cowsay "data imported, yay!"

It’s pretty self explanatory I guess, and MUCH faster and more reliable than any other way of doing this :-)

My backup should finish downloading any second now, so… cya soon!

Wymuszanie przedrostka www.

Ktoso — Mon, 17 Aug 2009 11:05:30 +0000

W razie jakby ktoś potrzebował wymuszać dodawanie przedsrostka www do adresu swojej strony (co może ułatwić życie użytkownikom i wyszukiwarkom, bo nie będzie jakby “kopii” jest samej strony pod innym adresem (bez www.)). Wystarczy zastosować poniższy kawałek kodu w pliku .htaccess:
RewriteEngine On #wymuś adres z przedrostkiem www. RewriteCond %{HTTP_HOST} ^blog.project13.pl [NC] RewriteRule ^(.*)$ http://www.blog.project13.pl/$1 [L,R=301]

Czemu o tym piszę? Ponieważ pierwszym wynikiem w google, jest strona gdzie za tą informację trzeba sowicie zapłacić… Co dość irytuje, zważywszy na to jakie to łatwe jeżeli się rozumie choćby podstawy mod_rewrite i wyrażeń regularnych. Pozdrawiam i odradzam płaceniu za ogólnie dostępną wiedzę ;-)

Przy okazji chciałem polecić bardzo fajną “ściągawkę” do mod_rewrite (oraz innych rzeczy, np. wyrażeń regularnych), którą przygotował Dave Child na swoim blogu: ILoveJackDaniel”s.com. Ogólnie to czuję że dogadałbym się z nim, również w kwestiach wyboru napoju ;-) /**Nie bez powodu mam kalendarz wujka Jack”a na ścianie ;-)*/