The PalMA web application requires a web server (usually Apache 2) which supports PHP 2 and SQLite.
User provided contents are shown using a simple web browser (dwb), an image viewer (eog, will be replaced by feh), a video player (vlc) and an office suite (libreoffice).
PalMA controls running viewers using wmctrl and xdotool.
So a complete PalMA installation can be based on Debian GNU Linux (Jessie). Just add some required Debian packages (these and all other installation commands must be run as root user):
apt-get install apache2 dwb eog feh libapache2-mod-php5 libjs-jquery
apt-get install openbox php5-curl php5-gd php5-intl php5-sqlite
apt-get install ssvnc sqlite3 vlc wmctrl xdotool zathura
Some more packages are optional:
apt-get install gettext git libavcodec-extra unattended-upgrades
The last one must be configured:
dpkg-reconfigure unattended-upgrades
More advanced users will also want to configure mail:
dpkg-reconfigure exim4-config
The PHP5 default configuration for the Apache2 webserver permits file uploads up to 2 MB. This limit is too low for typical documents (images, office documents, pdf). Change the setting upload_max_filesize in /etc/php5/apache2/php.ini. 10 MB is a good value. There is another limit for the maximum size of HTML posts with a default value of 8 MB. As this is less than the 10 MB needed for file uploads, the setting post_max_size must also be increased by setting it to 10 MB.
The following description assumes that the web server's root directory is /var/www/html (this is the default on newer versions of Debian) and that PalMA is directly installed there.
Of course it is also possible to install PalMA in any other path.
Get the latest version of PalMA from GitHub:
# Get latest PalMA. Add --branch v1.1.0 to get that version.
git clone https://github.com/UB-Mannheim/PalMA.git /var/www/html
# Create or update translations of PalMA user interface (optional).
make -C /var/www/html
The web server wants to create and modify a sqlite3 database palma.db,
so www-data needs write access to the installation directory.
For file uploads, a writable directory upload is created automatically. This also needs write access for www-data to the installation directory.
Some viewer programs want to write their configuration data. This requires
write access for www-data in directory ~www-data (typically /var/www).
Adding write access for www-data can be done by fixing the ownership:
chown -R www-data.www-data /var/www
# Activate javascript for Apache. TODO: Is that necessary?
#$ a2enconf javascript-common
Normally, PalMA should be started automatically. Activate autostart with these commands:
cp /var/www/html/scripts/palma /etc/init.d
update-rc.d palma defaults
Now a configuration file /var/www/html/palma.ini must be added.
A template for this file is available from subdirectory examples, so run
this command to get a preliminary file:
cp /var/www/html/examples/palma.ini /var/www/html/palma.ini
Some entries in palma.ini still need to be fixed for your local installation.
These include at least the entries stationname, theme, start_url and
control_file.
Most site specific settings are kept in a special subdirectory under theme.
A new PalMA installation can add its own subdirectory which optionally can
include more subdirectories if the installation uses several different
settings.
Each setting includes files for the screensaver, several images and icons, and a preconfigured Windows executable (UltraVNC SC). See theme/THEMES.md for details.
PalMA initially supported English and German user interfaces for the web frontend. Students from the University of Mannheim provided additional translations. More translations can be added on demand.
All translated texts are under subdirectory locale.
Newly added languages also need modifications in Makefile
and in gettext.php.
In a Debian GNU Linux installation, it is also necessary to add matching
locales, either by running dpkg-reconfigure locales manually or by enabling
the locales in /etc/locale.gen and running locale-gen. Here is an
example which enables the English locale in its US variant (en_US.UTF-8):
perl -pi -e s/^#.en_US.UTF-8/en_US.UTF-8/ /etc/locale.gen && locale-gen
PalMA currently includes translations for these locales:
de_DE.UTF-8, en_US.UTF-8, it_IT.UTF-8, ru_RU.UTF-8.
PalMA uses external applications as viewers for the different document types. For HTML, a web browser is needed. midori, netsurf, dwb, surf, xombrero, uzbl.
A low cost (less than 50 EUR plus monitor) PalMA station can be built using the Raspberry PI. The following configuration which is based on the Rasbian distribution (http://www.raspbian.org/) was successfully tested with a Raspberry PI 1:
apt-get install dwb eog feh libjs-jquery nxinx-light openbox
apt-get install php5-cgi php5-cli php5-curl php5-fpm php5-gd php5-intl php5-sqlite
apt-get install ssvnc sqlite3 vlc wmctrl xdotool zathura
mkdir -p /var/www/html
chown www-data:www-data /var/www/html
We replaced the apache2 web server by nxinx because it uses much
less ressources. Fix the server root and enable PHP5 in the configuration
file /etc/nginx/sites-enabled/default:
server {
root /var/www/html;
index index.html index.htm index.php;
# ...
location ~ \.php$ {
fastcgi_split_path_info ^(.+\.php)(/.+)$;
fastcgi_pass unix:/var/run/php5-fpm.sock;
fastcgi_index index.php;
include fastcgi_params;
}
}
Older versions of the Raspberry PI use a single core 700 MHz ARM CPU with only 256 or 512 MB RAM. They won't be able to run LibreOffice, so PalMA won't be able to show Office documents.
The latest version Raspberry PI 2 has a 900 MHz quad-core ARM Cortex-A7 CPU with 1 GB RAM. This is a good base for running PalMA without any software restrictions. It is still limited to full HD video resolution.