Thoughts about computer technologies

Debian+Apache+Tomcat+Axis

2009-10-09T06:08:00.001-07:00

Hello,
one of the courses I'm following at the university is "Laboratorio di reti
di calcolatori" which uses the technologies (really technologies?????)
listed in the post title. This is a little tutorial for making them works,
with a little script for registering .wsdd files.

- aptitude install apache2 tomcat6
- download the binaries of axis 1.x (latest is 2.x, it's not used in our course) and xerces then unpack them.
- copy *.jar of xerces into the "lib" dir of axis.
- create "/etc/tomcat6/policy.d/99axis.policy" with:

grant codeBase "file:/var/lib/tomcat6/webapps/-" {
permission java.security.AllPermission;
};

- copy the "axis" directory found under webapps of the axis binaries into /var/lib/tomcat6/webapps
- invoke-rc.d apache2 restart
- invoke-rc.d tomcat6 restart

Now go to http://localhost:8080 to make sure that Apache-Axis works.

Finally, this is the script for deploying web services (call it deploy.sh):

export AXIS_HOME="/home/lethal/ingegneria/reti/axis/axis-1_4"
export AXIS_LIB="$AXIS_HOME/lib"
export AXISCLASSPATH="$AXIS_LIB/axis.jar:$AXIS_LIB/commons-discovery-0.2.jar:$AXIS_LIB/commons-logging-1.0.4.jar:$AXIS_LIB/jaxrpc.jar:$AXIS_LIB/saaj.jar:$AXIS_LIB/log4j-1.2.8.jar:$AXIS_LIB/xml-apis.jar:$AXIS_LIB/xercesImpl.jar"
java -cp "$AXISCLASSPATH" org.apache.axis.client.AdminClient -lhttp://localhost:8080/axis/services/AdminService "$1"

In the script, you must tweak the AXIS_HOME variable to point to the unpacked axis binaries: avoid using spaces in this variable or you'll encounter several errors in terms of classpath.
Usage of the script:

sh deploy.sh file.wsdd

We're done!

Speeding up zsh completion

2009-10-07T14:23:00.001-07:00

Hello,

since I've started using zsh, a great shell with great out of the box completion, one of the most boring issues was having a really slow completion. I can understand it could be slow to get a list of packages, remote files or command line options, but also paths were often slow to be completed. After lots of searches I've ended up in adding this magic line to my ~/.zshrc:

zstyle ':completion:*' accept-exact '*(N)'

This way you tell zsh comp to take the first part of the path to be exact, and to avoid partial globs. Now path completions became nearly immediate.

Another important speed up is using the cache for packages and other stuff:

zstyle ':completion:*' use-cache on
zstyle ':completion:*' cache-path ~/.zsh/cache

If you know how to boost up options/remote files, please share :)

New GPG key

2009-08-29T05:46:00.000-07:00

Hello,
due to some synchronization problems between my desktop and laptop, unfortunately I've lost my GPG secret key. I was planning to renew my key after the SHA issues, but this way I can't neither revoke the old key nor sign the new key. So I please anybody having my pubkey to delete it:
gpg --delete-key C29A9371

I've uploaded my new key as usual so you can get it:
gpg --keyserver pgp.mit.edu --recv-keys D2C27B6B

Spadi source code

2009-08-09T11:10:00.000-07:00

Hello,
after I've written really a few docs, and cleaned up some stuff, I've published the code of both Spadi and Corraza on gitorious here. In the while, I've added support for floors and closeable views.
Help... help is needed.

Stay tuned.

Constructing a free ArchiCAD alternative

2009-08-06T04:02:00.000-07:00

Hello,
together a couple of university mates we talked about a possible free (as in freedom) ArchiCAD alternative. There are several free CAD out there but none is free for architects/engineers. The project is too big and ambitious, but I wanted to give OpenGL a shot with this excuse to learn something new.

I've started two projects:

Corraza, the OpenGL framework for editing 3d objects and exporting the scene graph to ray tracing software... think about a very very very minimal blender but as library

Spadi, the GTK+ application that runs on top of Corraza

You can find a video here to see what it can do now, after a week of development.
There's no code published at the moment, contact me if you would like to join the development.

Stay tuned.

Aruanne, pdf reporting framework

2009-07-21T23:34:00.000-07:00

Hello,
a while ago I've been talking about pango cairo and how to generate pdf with a couple of tables.
In the meantime I've worked on it, improving and enhancing new kinds of elements. This has lead to the creation of a small project, a library providing a simple framework for generating mostly PDF reports (I haven't tried to generate SVG or something else yet).

After a couple of release requests, I've found finally the time to publish a sort of working code.

Here's the git repository and here you can download the snapshot tarball.

Any patches welcome.

The less consuming radio player ever

2009-06-20T13:10:00.000-07:00

Hello,
multimedia always killed desktop performance, also audio with all such effect-based players out there. I've been using deezer for a long time, but sometimes I'm tired to see my desktop lagging.
I don't need that, I need random music from internet while I'm either programming or studying, and my computer has only 512mb ram and 2.4ghz amd64 (onLY??? yes nowadays it's a little amount).

Let's see what we can do using gst-launch:


while [ 1 ]; do wget -q -O - http://66.250.45.112:80/hard.ogg|gst-launch fdsrc fd=0 ! decodebin ! audioconvert ! alsasink; done

The URL above is a hard rock station :) The while ensures re-connection. I think performances are great, 6% cpu and 2% ram.

But there's yet a bettere solution (see comments):


mplayer http://66.250.45.112:80/hard.ogg

Syx changes web and git hosting

2009-05-29T15:45:00.000-07:00

Hello,
I'm officializing the change of web hosting and git hosting from googlecode to berlios:

The new website is up!

For several reasons, including reliability, we switched both the website and git hosting to berlios. Also the purpose of this change is to rewrite the website backend using Syx.

The mailing list and the bug tracker are still hosted at googlecode.

Some progress news in the while

We're working on a new memory management, object representation and garbage collector. On the other side the lack of time is making things harder for releasing the new version. Together with the above changes, new Smalltalk standard pieces will implemented as usual. I remind you the new code is in

the object branch.

Website: http://syx.berlios.de

GIT: git://git.berlios.de/syx

Project page: https://developer.berlios.de/projects/syx/

Render tables with pangocairo like reportlab

2009-05-27T14:22:00.000-07:00

Hello,
lately I was wondering if there was any alternative to the well known reportlab python software for creating PDF reports. I immediately thought about Cairo. The only two problems are:

Cairo doesn't create multiple pages
No support for creating tables containing text, necessary for table-based reports

I still can't realize how to achieve the first feature, but the second one could be solved using Pango layouts.

The idea is to create the cells of the table using such layouts, so that the text get wrapped etc.

Here's the Pango tables code snippet containing the necessary classes for achieving the job. Notice that the methods in the snippet often make use of Pango units instead of pixels.

Now let's use the Table class as follows: create a table with two rows and two columns, then show it twice with different background colors.

surface = cairo.PDFSurface ("test.pdf", 300, 400)
cr = cairo.Context (surface)
cr = pangocairo.CairoContext (cairo.Context (surface))

sizes = [pango.SCALE*12*10, pango.SCALE*12*10]
data = [["first test with pango tables", "seems to work correctly"],
   ["though it needs", "support for borders and spans"]]

table = Table (cr, sizes, data, pango.FontDescription ("Sans 12"))
cr.rectangle (0, 0, pango.PIXELS(table.get_width ()), pango.PIXELS(table.get_height()))
cr.set_source_rgb (0.8, 0.8, 0.8)
cr.fill ()
cr.set_source_rgb (0, 0, 0)
table.show_table (cr)

cr.translate (0, 200)
cr.rectangle (0, 0, pango.PIXELS(table.get_width ()), pango.PIXELS(table.get_height()))
cr.set_source_rgb (0.4, 0.5, 0.7)
cr.fill ()
cr.set_source_rgb (0, 0, 0)
table.show_table (cr)

Here's the result test.pdf:

Blogging from Epiphany WebKit

2009-05-18T11:33:00.000-07:00

Hello,
I've been using Midori for a while. It's a great browser: innovative and light. However all my bookmarks and data are in Epiphany. Last week the new epiphany-webkit version has been uploaded in Debian Sid and I couldn't wait to test it. I'm currently using it instead of gecko; it has still some issues but I begun living without it.

Create a GdkPixbuf from cairo surface

2009-04-26T10:40:00.000-07:00

Hello,
here's the inverted code snippet of the previous post.

w, h = surface.get_width(), surface.get_height()

pixmap = gtk.gdk.Pixmap (None, w, h, 24)

cr = pixmap.cairo_create ()

cr.set_source_surface (surface, 0, 0)

cr.paint ()

pixbuf = gtk.gdk.Pixbuf (gtk.gdk.COLORSPACE_RGB, True, 8, w, h)

pixbuf = pixbuf.get_from_drawable (pixmap, gtk.gdk.colormap_get_system(), 0, 0, 0, 0, w, h)

Create a cairo surface from a pixbuf

2009-04-25T02:03:00.000-07:00

Hello,
sometimes in the code of a couple of projects I see some hard algorithms to transform a pixbuf in a cairo surface.
Maybe most of people don't know that GdkCairoContext, contrarily to cairo_t, is created against a cairo context not a cairo surface:

surface = cairo.ImageSurface (cairo.FORMAT_ARGB32, pixbuf.get_width(), pixbuf.get_height())

cr = cairo.Context (surface)

gdkcr = gtk.gdk.CairoContext (cr)

gdkcr.set_source_pixbuf (pixbuf)

gdkcr.paint ()

Notice gtk.gdk.CairoContext (cr), which cr is not the surface. That's the key of the code snippet.

For instance this can be applied on a ClutterCairoTexture to render pixbufs in the canvas.

Awesome/other wrong keyboard layout

2009-02-27T15:12:00.001-08:00

Hello,
due to the high resource usage by Eclipse (I have to use that unfortunately because of my professor) I've temporarly dropped GNOME and now I'm using Awesome for a while.

Ok let's say the problem: the keyboard. Do you have different languages, layouts and so on among several configurations (GNOME, X, ...) and your keyboard layout is messed up with awesome?
Just do it:

setxkbmap -layout YOURLAYOUT

Where YOURLAYOUT for me is it.

I've found this utility in this mailing thread. Yet you can read that awesome is still too young and lacks some keyboard configuration features.

Have fun!

JMF and MPEG

2009-02-24T14:11:00.000-08:00

Hello,
I'm recently writing a game with Java AWT/Swing/SwingX/JMF for a university exam.
If you are using the Java Media Framework and most of the formats (all the well known and used formats) can't be handled by the library here's your definitive solution to the problem.
You will usually get "Unable to handle format: MPEG" or something like that.

How do you get rid of that and make things work? There's a great plugin named jffmpeg which handles a huge number of audio and video formats (including ogg/vob).
Just follow the instructions on the project website to install the plugins.

Alternatively you can register only the codec and demux you use from within your application code as follows (e.g. only handle MPEG video format on input):

Format[] inFormats = { new VideoFormat ("MPEG") };

PlugInManager.addPlugIn ("net.sourceforge.jffmpeg.VideoDecoder", inFormats, null, PlugInManager.CODEC);

PlugInManager.commit ();

FreeSpeak 0.3.0 has been released

2009-01-10T02:42:00.000-08:00

FreeSpeak is a free (as in freedom, developed and released under the terms of GPL) frontend to online translator engines (such as Google, Yahoo, etc.). It is written in Python, it uses the GTK toolkit and some GNOME infrastructure features.

This is a major enhancemenfts release.

Overview of Changes from FreeSpeak 0.2.0 to FreeSpeak 0.3.0
===========================================================

* Project is now hosted at BerliOS.de: http://freespeak.berlios.de

* Support for cancellating operations has been added

* Translation suggestions (open-tran) have been added

* A menubar has been added and the toolbar has been cleaned up

* The behavior of language/translation selection has been fixed and improved

* GNOME documentation has been added

* Dependencies in the configuration have been cleaned up

* Support for global keybindings has been added through python-xlib

* An introduction widget for the main window has been created

Mailbox-to-mbox

2008-12-26T10:54:00.000-08:00

Hello,
lately I've been looking for a way to convert a mailman archive to an mbox format so that I could open with mutt.
I then found a couple of scripts, but the one I've found simpler and working for my needs is mailbox2mbox.pl.
Sample usage:


$ gunzip YourArchive.txt.gz
$ perl mailbox2mbox.pl < YourArchive.txt > mbox
$ mutt -f mbox

And it simply works!
Does anybody know a method as simple as the above one but more powerful?

PS: Happy holidays!

Global keybinding on X

2008-12-21T01:52:00.000-08:00

Hello,
lately I've been looking for a way to create a desktop-wide keybinding for FreeSpeak.
I first looked into Tomboy and Deskbar source codes but the egg was too huge to be adopted, and it would have brought C dependency which isn't always nice for a Python project.
Then fargiolas pointed me to a blog post where I could find about gnome keybindings owned by gnome control center. Well that was only a mirage as it doesn't really grab the key but it's only a visual entry in the keyboard shortcuts preferences.
After a few days I've finally found a not-so-hackish solution in about one hundred lines of Python code.

Here is the snippet (download), only using Xlib and GTK+ Python bindings.

Sample usage:


def callback (keybinding):
   print 'Callback!'
   gtk.main_quit ()

gtk.gdk.threads_init ()
keybinding = GlobalKeyBinding ("/apps/appdir", "key_binding")
keybinding.connect ('activate', callback)
keybinding.grab ()
keybinding.start ()
gtk.main ()

The only problem is that it doesn't make use of GDK filters because PyGTK doesn't provide such function wrappers and there's no GDK-to-Xlib mapping available.
But yes, it works very good.

Aptitude-gtk progress

2008-12-01T14:58:00.001-08:00

Hello,
I was curious to see if aptitude-gtk was making some progress. I haven't followed the project since it's been merged into aptitude.
Well, I found it more functional and complete. Here's a screenshot showing pending packages for upgrade after an update:

From GNOME

The team is definitely doing a good job. Hopefully I'll find the time to give some help as I'm really interested in such full-featured GUI frontend.
Keep going on!

FreeSpeak gains translation suggestions

2008-11-30T03:47:00.000-08:00

Hello,
it hasn't been a long time since FreeSpeak 0.2.0 has been released. One of the TODOs for the next release was to support open-tran, and more over translation suggestions for development.
This is a screenshot of what's been included in the repository today:

From GNOME

FreeSpeak is a GNOME frontend to online translator engines.

FreeSpeak 0.2.0 has been released

2008-11-28T03:57:00.000-08:00

Hello,
after some work in these weeks now I have released a new version of FreeSpeak.

FreeSpeak is a free (as in freedom, developed and released under the terms of GPL) frontend to online translator engines (such as Google, Yahoo, etc.). It is written in Python, it uses the GTK toolkit and some GNOME infrastructure features

.

It's been rewritten almost from scratch so I think there's no need to post release notes here. Anyway you can always read what changed from the old version released a couple of years ago here.

Notice that the project homepage has been changed. The project has now moved to BerliOS.de.

Replace GTK+ with Clutter for fun

2008-11-23T12:38:00.000-08:00

Hello,
lately I was having fun with Clutter and Python. I've started by creating some Gtk-like widgets (such as GtkWindow, GtkBox, and GtkButton) in Clutter.
Well, this is the result... it's a simple example of a very poor toolkit, but it works:

Try it, it's only one .py file source code

Single app instances, Python and DBus

2008-11-16T10:01:00.000-08:00

Hello,
I'm working on FreeSpeak lately and I needed to run the application once per session, as it's got a trayicon and a notebook (maybe windows with an applet is better?)
I decided to use DBus for making the application run only a single instance; when you try to open it again it won't start another process, instead it will use the already running one.

This is how I would create a generic single app instance with dbus-python:

import dbus
import dbus.bus
import dbus.service
import dbus.mainloop.glib
import gobject

class Application (dbus.service.Object):
  def __init__ (self, bus, path, name):
    dbus.service.Object.__init__ (self, bus, path, name)
    self.loop = gobject.MainLoop ()

 @dbus.service.method ("org.domain.YourApplication",
                       in_signature='a{sv}', out_signature='')
 def start (self, options={}):
   if self.loop.is_running ():
     print 'instance already running'
   else:
     self.loop.run ()

dbus.mainloop.glib.DBusGMainLoop (set_as_default=True)
bus = dbus.SessionBus ()
request = bus.request_name ("org.domain.YourApplication", dbus.bus.NAME_FLAG_DO_NOT_QUEUE)
if request != dbus.bus.REQUEST_NAME_REPLY_EXISTS:
 app = Application (bus, '/', "org.domain.YourApplication")
else:
 object = bus.get_object ("org.domain.YourApplication", "/")
 app = dbus.Interface (object, "org.domain.YourApplication")

# Get your options from the command line, e.g. with OptionParser
options = {'option1': 'value1'}
app.start (options)

How it works?

Setup the mainloop for dbus
Request a session bus name, so that other applications (in our case another instance of the same application) can connect to it
Create a new instance at path / if the bus name doesn't exist (so we are the primary owner). If it exists, then obtain the object from dbus and call the method on the remote Application object using the known interface.
The Application.start method checks if it's already running then decide what to do in both situations.

Creating a GTK+ application this way is really easy. It only needs to use the GTK+ mainloop.
Let's suppose we want to present() the GtkWindow when the user tries to open another instance of the application:

import dbus
import dbus.bus
import dbus.service
import dbus.mainloop.glib
import gobject
import gtk
import gtk.gdk
import time

class Application (dbus.service.Object):
 def __init__ (self, bus, path, name):
   dbus.service.Object.__init__ (self, bus, path, name)
   self.running = False
   self.main_window = gtk.Window ()
   self.main_window.show_all ()

 @dbus.service.method ("org.domain.YourApplication",
                       in_signature='', out_signature='b')
 def is_running (self):
   return self.running

 @dbus.service.method ("org.domain.YourApplication",
                       in_signature='a{sv}i', out_signature='')
 def start (self, options, timestamp):
   if self.is_running ():
     self.main_window.present_with_time (timestamp)
   else:
     self.running = True
     gtk.main ()
     self.running = False

dbus.mainloop.glib.DBusGMainLoop (set_as_default=True)
bus = dbus.SessionBus ()
request = bus.request_name ("org.domain.YourApplication", dbus.bus.NAME_FLAG_DO_NOT_QUEUE)
if request != dbus.bus.REQUEST_NAME_REPLY_EXISTS:
 app = Application (bus, '/', "org.domain.YourApplication")
else:
 object = bus.get_object ("org.domain.YourApplication", "/")
 app = dbus.Interface (object, "org.domain.YourApplication")

# Get your options from the command line, e.g. with OptionParser
options = {'option1': 'value1'}
app.start (options, int (time.time ()))
if app.is_running ():
 gtk.gdk.notify_startup_complete ()

How it works?

Let's say we're running the Application for the first time, the loop begins and when it ends running is set to False, so gtk.gdk.notify_startup_complete() won't be called. Instead, if the application is already running, start() will be called on the remote object running the loop. The method then returns immediately so gtk.gdk.notify_startup_complete() will be called.
If you don't notify to the launcher that the startup is complete... guess what happens to your mouse and to your taskbar panel...

If the loop is running, the window is presented to the user with a little delay. If you don't use any timestamp, the UI interaction won't let the window have the time to be presented.

Of course, you can use DBus for many more things, like both setting options from the command line, as explained in the above code, and let other applications communicate with yours and viceversa.
Nowadays almost all systems use DBus, so it won't be a pain to add such dependency. In my opinion, it would be much more painful to use lock files, FIFO, unix sockets or whatever. FreeSpeak used such old technologies and it was a very poor emulation of what DBus already offers.

ping.fm is dead

2008-10-20T13:39:00.000-07:00

Hello,
lately I've been using ping.fm for a couple of weeks because I've found it really useful.
Today I've tried to update my status through sending a mail but I received delivery failures... I then discovered that ping.fm is dead!

FreeSpeak, a GTK+/GNOME translator

2008-10-14T14:31:00.001-07:00

Hello,
I've worked on FreeSpeak a couple of years ago, a Python/GTK+/GNOME project to translate text and web pages by querying already existing online translation tools.
PRO: It has been packed for Ubuntu and it has been publicized by a journal in Italy.
CONS: It has been discontinued until now. In fact I restarted the project and I'm doing a huge refactoring because of the ugly code I wrote in the past.

It's already working, but some features are still missing.
The new approach will allow applications to use FreeSpeak as a Python library to embed the translation widgets.

Contact me if you intend to help the project with suggestions, bug reports, critiques and coding.

How to contribute to APT

2008-10-10T09:12:00.000-07:00