source: trunk/docs/tutorial/environment.txt @ 345

.. _environment:

Using ZOO from an OSGeoLive virtual machine
===========================================

Development Environment Description
-----------------------------------

`OSGeoLive <http://live.osgeo.org/>`__ is a live DVD and virtual machine based on 
`Xubuntu <http://www.xubuntu.org/>`__  that allows you to try a 
wide variety of open source geospatial software without installing anything. It is 
composed entirely of free software and include ZOO 1.0 this year, for testing purpose.

As already said in introduction, an OSGeoLive virtual machine image disk has been 
installed on your computer, allowing you to use ZOO Kernel in a development environment 
directly. Using a virtual machine image disk seems to be the simplest way to use 
ZOO Kernel and to develop ZOO Services locally, as we can ensure that everything 
requested for compile C Services and run Python Services is available and ready to use. 
Every ZOO related material and source code have been placed in */home/user/zoows* directory. 
We will work inside it during this workshop. As the binary version of ZOO Kernel is 
already compiled and stored in */home/user/zoows/sources/zoo-kernel*, you only have to 
copy two important files inside the */usr/lib/cgi-bin directory*: *zoo_loader.cgi*
and the *main.cfg* in order to make ZOO Kernel available, using the following commands:

::

  sudo cp ~/zoows/sources/zoo-kernel/zoo_loader.cgi /usr/lib/cgi-bin
  sudo cp ~/zoows/sources/zoo-kernel/main.cfg /usr/lib/cgi-bin
  
Please note that we will talk about ZOO Kernel or zoo_loader.cgi script without any 
distinction during this workshop.

The *main.cfg* file contains metadata informations about the identification and provider 
but also some important settings. The file is composed of various sections, namely *main*,  
*identification* and *provider* per default. Obviously, you are free to add new sections 
to the files if you need them for a specific Service. Nevertheless, you have to know 
that the env section name is used in a specific way. It lets you define environment 
variables that your Service requires during its runtime. For instance, if your Service 
requires to access to a X server running on framebuffer, you can add *DISPLAY=:1* line in 
your env section to take this specificity into account.

Please have a look to this file. Three important parameters are commented below:

serverAddress
  The url to access to the ZOO Kernel

tmpPath
  The full path to store temporary files

tmpUrl
  The url path relative to serverAddress to access temporary directory.

The values of the *main.cfg* file used from the running virtual machine are the following:

::

  serverAddress=http://localhost/zoo
  tmpPath=/var/www/temp
  tmpUrl=../temp/

You could have noticed that the *tmpUrl* is a relative url from *serverAddress*, so it must 
be a directory. Even if ZOO Kernel can be used with the full url of the zoo_loader.cgi 
script, for  better readability and fully functional ZOO Kernel, you have to modify the 
default Apache configuration in order to be able to use the http://localhost/zoo/ url 
directly.

First, please create a zoo directory in the existing */var/www* which is used by Apache as 
the DirectoryIndex. Then, please edit the */etc/apache2/sites-available/default* configuration 
file and add the following lines after the Directory block related to */var/www* directory :

::

  <Directory /var/www/zoo/>
          Options Indexes FollowSymLinks MultiViews
          AllowOverride All
          Order allow,deny
          allow from all
  </Directory>
  
Now create a small *.htaccess* file in the */var/www/zoo* containing the following lines:

::

  RewriteEngine on
  RewriteRule (.*)/(.*) /cgi-bin/zoo_loader.cgi?metapath=$1 [L,QSA]
  RewriteRule (.*) /cgi-bin/zoo_loader.cgi [L,QSA]

For this last file to be taken into account by Apache, you must activate the rewrite 
Apache module by copying a load file as bellow :

::

  sudo cp /etc/apache2/mods-available/rewrite.load /etc/apache2/mods-enabled/

Now you should be able to access the ZOO Kernel using a simplified by restarting 
your Apache Web server :

::

  sudo /etc/init.d/apache2 restart
  
Two other softwares form the OSGeoLive environment will be used during this workshop. 
Geoserver will first be used to provide WFS input data for the ZOO Services we are going 
to develop. The Geoserver sample dataset (United States polygons) will be passed to our 
service during section 3. So please start the Geoserver using the corresponding launcher 
in the Servers folder, as illustrated in the following screenshot :

OpenLayers library is also available on the OSGeoLive virtual machine image disk, and it 
will be used during section 4, for building a simple WPS client application able to query 
the newly developed ZOO Services. 

As we planned to use OGR C-API and Python module of the GDAL library, we will need the 
corresponding header files, libraries and associated files. Hopefully everything was 
already available per default and so ready to use on the OSGeoLive packaging.