How to install latest stable Node.js on Ubuntu

HowTo, Linux, Programmazione, Ubuntu (EN) 3 Comments »

If you develop with Node.js and you want to be sure to have the latest stable version, luckly there is a PPA for it. All you need is to follow these instructions:

sudo apt-get install python-software-properties python g++ make
sudo add-apt-repository ppa:chris-lea/node.js
sudo apt-get update
sudo apt-get install nodejs npm

That's it!

Reference: https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager

The Windows Phone Emulator wasn’t able to connect to the Windows Phone operating system: how to fix it

HowTo, Programmazione, Windows, Windows Phone No Comments »

This morning when I started my Windows Phone 8 emulator to test an application, the emulator refused to work, giving me this error "The Windows Phone Emulator wasn’t able to connect to the Windows Phone operating system". Luckly it's very easy to fix. It's caused by the virtual network interface that has been disabled for some reason (well... in my case it must depend on the other day when I tryed to trick WP7 firmware upgrade and used the disconnect trick, but this is another story).

I searched on Google for a solution and I landed on this page http://pauliom.com/2012/12/20/the-windows-phone-emulator-wasnt-able-to-connect-to-the-windows-phone-operating-system/

All you have to do is going to "Network and Internet --> Network Connections", right click on "vEthernet (Internal Ethernet Port) Windows Phone Emulator" and Enable it.

network_interface_wp8

Using QtCreator to deploy and run a Qt application to a remote Linux device

HowTo, Linux, Programmazione, Qt, Ubuntu (EN) 2 Comments »

QtCreator is a very flexible IDE and can really be adapted for a lot of things. I usually use it to develop mobile applications for Nokia N9 and BlackBerry 10, but it can be used for more generic tasks. In my case I wanted to be able to develop a Qt application using my desktop PC, deploy it and run on a remote (actually it's on the same desk) Linux machine running Xubuntu.

Doing this is quite easy and you don't need any specific plugin on QtCreator, but be sure to have at least version 2.6.x. Other than QtCreator you also need two Linux based PC (I used Ubuntu 12.10 for my development machine and Xubuntu 12.10 for the remote netbook) and an SSH account on the remote PC.

Add the remote device to QtCreator

QtCreatorDevice

To add the remote Linux device on QtCreator, use the Tools->Options menu and click on "Devices" item. At this point click on "Add" button and fill the fields using values similar to the screenshot. In particular specify a name for the device, the IP of the remote machine and a username and password that must already exist (I just created the user "andrea" on the Xubuntu machine and used the same password). I also had to set the timeout to 20 seconds, because I had some connection problems and the connection kept dropping after 10 seconds trying. To verify if everything is working fine, just click on Test button.

Add a specific Qt version

QtCreatorQtVersion

To write your application you may need a specific Qt version that is different from the one distributed by your Linux distribution. There's no problem, QtCreator let you add different Qt versions without any conflict. In my case I installed the Qt5 version distributed by Canonical Qt5 Edgers Teamhttps://launchpad.net/~canonical-qt5-edgers
Once it's installed, just click on "Add" button and select the qmake specific to the version you want to add (in my case it was in /opt/qt5/bin/qmake ).

Add a Qt Kit

QtCreatorQtKits

QtCreator permits to add new Kit (development configurations) and these kits are used during project creation to specify what you want to target. In my example I added a new kit choosing an appropriate name "Qt5 Ubuntu", the device type, the actual device previously configured and finally the Qt version that we added before. With a kit I have a complete "toolchain" that allow me to write applications for a particular device, with a specific Qt version.

Putting the pieces together

At this point you just have to create a new "Qt Quick 2" application, and select the new kit you just created instead of the "Desktop" one. Please note that there is a little problem that I haven't fixed yet (but I'm working on it): if you create, for example, a project named "QtTest1" it will be deployed to the folder /opt/QtTest1/ on the remote machine. By default your user doesn't have read+write permissions for that folder so I manualy created the folder and I gave a chmod 777 on it, just for testing. There are two possible ways to fix this: you could create a specific user that has read+write permissions on /opt/ or you could modify the deployment configuration to have the app deployed to the user /home (I will investigate on this possibility and I will write something in one of the next posts).

Final thoughts

What all of this could be useful for? Well, do 2+2 and you'll easily guess ;) In the next weeks I will post more specific informations and I will update everyone with my progresses. Any comment is welcome! If you want to contribute to this you're welcome too of course.

Spotify 0.8.8 for Linux crashes if it cannot connect to Internet: how to fix it

HowTo, Linux, Ubuntu (EN) 1 Comment »

If you upgrade Spotify for Linux to 0.8.8.x version and you have some network connection problems (for example you're behind a company firewall and need to set a proxy...) the application will crash/hang without letting you doing anything (neither setting Proxy informations)

Screenshot from 2013-01-06 18:56:15

This is caused by a deadlock in the GUI and you can view the complete debugging informations here http://pastebin.com/zcKgXEqz
To fix this, you just need to open this file ~/.config/spotify/prefs and add these two lines:

network.proxy.addr="123.123.123.123:1234@https"
network.proxy.mode=2

of course substituting 123.123.123.123:1234 with your proxyip:proxyport.

Using Cloud9 IDE to develop Django applications

HowTo, Programmazione, Python, Ubuntu (EN) 3 Comments »

Django is becoming very popular for dynamic websites development (actually it already is) so I decided to start learning it, with the help of a good book. To develop Django web applications you need a good IDE and an environment that support at least Python and a database (SQL Lite, MySQL etc...). If you have multiple machines and you alternate from multiple operating systems, the best thing is using an environment that you can use everywhere, from your favourite browser.

Here comes Cloud9, a very nice service that you could define as the "Google Docs" for developers. C9 offers you a shared, always available on the cloud, environment to write your code. They also offer access to a Linux terminal (so you can install applications, like Django) and your websites are istantly available online for remote testing.

c9ide_django

Installing and using Django on C9 is very easy. You just need to open a new terminal tab (ALT+T) in C9 and execute these commands

easy_install django
python ./../bin/django-admin.py startproject myproject
python ./myproject/manage.py runserver $OPENSHIFT_INTERNAL_IP:$PORT

After these commands, your Django website will be live and accessible using http://projectname.username.c9.io (where projectname is the name of the project you just created and username is your C9 user name).

source: http://support.cloud9ide.com/entries/21830983-django-development-in-c9

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