source: branches/ms-style/docs/kernel/configuration.rst @ 910

.. _kernel_config:

ZOO-Kernel configuration
========================

Main configuration file
-----------------------

ZOO-Kernel general settings are defined in a configuration file called
``main.cfg``. This file is stored in the same directory as ZOO-Kernel
(``/usr/lib/cgi-bin/`` in most cases). It provides usefull metadata information on your ZOO-Kernel installation.     

.. warning:: 
  ZOO-Kernel (``/usr/lib/cgi-bin/zoo_loader.cgi``) and its
  configuration file (``/usr/lib/cgi-bin/main.cfg``) must be in the
  same directory.
  
.. note:: 
  Information contained by ``/usr/lib/cgi-bin/main.cfg`` is accessible from WPS Services at runtime, so when *Execute* requests are used.

Default main.cfg
...............................

An example *main.cfg* file is given here as reference.

.. code-block:: guess
    :linenos:
    
    [headers]
    X-Powered-By=ZOO@ZOO-Project
    
    [main]
    version=1.0.0
    encoding=utf-8
    dataPath=/var/data
    tmpPath=/var/www/temp
    cacheDir=/var/www/cache
    sessPath=/tmp
    serverAddress=http://localhost/cgi-bin/zoo_loader.cgi
    lang=fr-FR,ja-JP
    language=en-US
    mapserverAddress=http://localhost/cgi-bin/mapserv.cgi
    msOgcVersion=1.0.0
    tmpUrl=http:/localhost/temp/
    cors=false
    
    [identification]
    keywords=t,ZOO-Project, ZOO-Kernel,WPS,GIS
    title=ZOO-Project demo instance
    abstract= This is ZOO-Project, the Open WPS platform. 
    accessConstraints=none
    fees=None
    
    [provider]
    positionName=Developer
    providerName=GeoLabs SARL
    addressAdministrativeArea=False
    addressDeliveryPoint=1280, avenue des Platanes
    addressCountry=fr
    phoneVoice=+33467430995
    addressPostalCode=34970
    role=Dev
    providerSite=http://geolabs.fr
    phoneFacsimile=False
    addressElectronicMailAddress=gerald@geolabs.fr
    addressCity=Lattes
    individualName=Gerald FENOY


Main section 
...............................

The main.cfg ``[main]`` section parameters are explained bellow.

 * ``version``: Supported WPS version.
 * ``encoding``: Default encoding of WPS Responses.
 * ``dataPath``: Path to the directory where data files are stored (used to store mapfiles and data when MapServer support is activated).
 * ``tmpPath``: Path to the directory where temporary files are stored (such as *ExecuteResponse* when *storeExecuteResponse* is set to true).
 * ``tmpUrl``: URL to access the temporary files directory (cf. ``tmpPath``).
 * ``cacheDir``: Path to  the directory where cached request files [#f1]_ are stored (optional).
 * ``serverAddress``: URL to the ZOO-Kernel instance.
 * ``mapservAddress``: URL to the MapServer instance (optional).
 * ``msOgcVersion``: Version of all supported OGC Web Services output [#f2]_
   (optional).
 * ``lang``: Supported natural languages separated by a coma (the first is the default one),
 * ``cors``: Define if the ZOO-Kernel should support `Cross-Origin
   Resource Sharing <https://www.w3.org/TR/cors/>`__. If this
   parameter is not defined, then the ZOO-Kernel won't support CORS.
 * ``servicePath``: Define a specific location to search for services
   rather than using the ZOO-Kernel directory. If this parameter is
   not defined, then the ZOO-Kernel will search for services using its
   directory.
 * ``libPath``: (Optional) Path to a directory where the ZOO-kernel should search for
   service providers, e.g., shared libraries with service implementations 
   (the ``serviceProvider`` parameter in the service configuration (.zcfg) file).   

.. warning:: 
  The ``libPath`` parameter is currently only recognized by services implemented
  in C/C++ or PHP, and may be moved to another section in future versions.
  
In case you have activated the MapServer support, please refer to
:ref:`this specific section <kernel-mapserver-main.cfg>`. 


Identification and Provider 
..........................................

The ``[identification]`` and ``[provider]`` sections are not ZOO-Project
specific. They provide OGC metadata [#f3]_ and should be set according
to the `XML Schema Document
<http://schemas.opengis.net/ows/1.1.0/ows19115subset.xsd>`__ which
encodes the parts of ISO 19115 used by the common
*ServiceIdentification* and *ServiceProvider* sections of the
*GetCapabilities* operation response, known as the service metadata
XML document.

Details of the common OWS 1.1.0 *ServiceIdentification* section can be
found in this `XML Schema Document
<http://schemas.opengis.net/ows/1.1.0/owsServiceIdentification.xsd>`__.

Details of the common OWS 1.1.0 *ServiceProvider* section can be
found in this `XML Schema Document
<http://schemas.opengis.net/ows/1.1.0/owsServiceProvider.xsd>`__.


Additional sections
--------------------------------

All the additional sections discribed in the following section are
optional.

Headers section
...............................

The ``[headers]`` section can be set in order to define a specific HTTP
Response header, which will be used for every response. As an example,
you can check http://zoo-project.org using *curl* command line tool
and notice the specific header *X-Powered-By: Zoo-Project@Trac*.

In case you want to allow CORS support for POST requests coming from
``myhost.net``, then you should define the following minimal
parameters in this section:

.. code-block:: guess
    :linenos:
    
    Access-Control-Allow-Origin=myhost.net
    Access-Control-Allow-Methods=POST
    Access-Control-Allow-Headers=content-type


env section
...............................

The ``[env]`` section can be used to store specific environment
variables to be set prior the loading of *Services Provider* and Service execution.

A typical example is when a Service requires the access to a X server
running on *framebuffer*, which takes to set the DISPLAY environnement
variable, as follow:

.. code-block:: guess
    :linenos:
    
    [env]
    DISPLAY=:1

In case you have activated the OTB support, please refer to :ref:`this
specific section <kernel-orfeotoolbox-main.cfg>`. 

lenv section
...............................

The ``lenv`` section is used by the ZOO-Kernel to store runtime informations
before the execution of a WPS service, it contains the following
parameters:

 * ``sid`` (r): The WPS Service unique identifier,
 * ``status`` (rw): The current progress value ( a value between 0 and
   100 in percent (**%**) ),
 * ``cwd`` (r): The current working directory of ZOO-Kernel,
 * ``message`` (rw): An error message used when ``SERVICE_FAILED`` is returned (optional),
 * ``cookie`` (rw): The cookie to be returned to the client (for
   example for authentication purpose).
 * ``file.pid`` (r): The file used by the ZOO-Kernel to store process identifier.
 * ``file.sid`` (r): The file used by the ZOO-Kernel to store service identifier.
 * ``file.responseInit`` (r): The file used by the ZOO-Kernel to store
   the initial (then final) WPS response.
 * ``file.responseFinal`` (r): The file used by the ZOO-Kernel to
   temporary store the final WPS response.

renv section
...............................

The ``renv`` section is automatically created by the ZOO-Kernel before
the execution of a WPS service, it contains all the environment
variables available at runtime (so including the header fields in case
it is used through http, refer to [https://tools.ietf.org/html/rfc3875
rfc3875] for more details).


senv section
...............................

The ``senv`` section can be used to store sessions information on the
server side. Such information can then be accessed automatically from
the Service if the server is requested using a valid cookie (as
defined in ``lenv`` section). ZOO-Kernel will store the values set in the
``senv`` maps on disk, load it and dynamically replace its content to
the one in the ``main.cfg``. The ``senv`` section must contain the
following parameter at least:

 * ``XXX``: The session unique identifier where ``XXX`` is the name
   included in the cookie which is returned.

.. _cookie_example:

For instance, adding the following in the Service source code  :

.. code:: python
    
    conf["lenv"]["cookie"]="XXX=XXX1000000; path=/" 
    conf["senv"]={"XXX": "XXX1000000","login": "demoUser"}

means that ZOO-Kernel will create a file named ``sess_XXX1000000.cfg``
in the ``cacheDir`` directory, and will return the specified cookie to the client. Each time the client will 
request ZOO-Kernel using this cookie, it will automatically load the
value stored before the Service execution.

Security section
...............................

The ``[security]`` section can be used to define what headers, the
ZOO-Kernel has initially received in the request, should be passed
to other servers for accessing resources (such as WMS, WFS, WCS
or any other file passed as a reference). This section contains two
parameters:

 * ``attributes``: The header to pass to other servers (such as
   Authorization, Cookie, User-Agent ...),
 * ``hosts``: The host for wich the restriction apply (can be "*" to
   forward header to every server or a coma separated list of host
   names, domain, IP).

Both parameters are mandatory.

Suppose you need to share Authorization, Cookie and User-Agent to
every server for accessing ressources, then yo ucan use the following
section definition:

.. code:: 

    [security]
    attributes=Authorization,Cookie,User-Agent
    hosts=*

In case only local servers require such header forwarding, you may use
the following definition:

.. code:: 

    [security]
    attributes=Authorization,Cookie,User-Agent
    hosts=localhost,127.0.0.1


.. _zoo_activate_db_backend:

Database section
...............................

The database section allows to configure the
:ref:`ZOO-Kernel optional database support <zoo_install_db_backend>`. 

.. code-block:: guess

        [database]
        dbname=zoo_project
        port=5432
        user=username
        host=127.0.0.1
        type=PG
        schema=public

This will generate strings to be passed to GDAL to connect the
database server:

.. code-block:: guess
   
    <type>:host=<host> port=<port>  user=<user> dbname=<dbname>


With the previous database section, it will give the following:

.. code-block:: guess

    PG:"dbname=zoo_project host=127.0.0.1 port=5432 user=username"

Please refer to this `section <zoo_create_db_backend>`_ to learn how
to setup the database.

Include section
...............................

The ``[include]`` section (optional) lists explicitely a set of service configuration files
the the ZOO-Kernel should parse, e.g.,


.. code-block:: guess
    :linenos:
    
    [include]
    servicename1 = /my/service/repository/service1.zcfg
    servicename2 = /my/service/repository/service2.zcfg

The ``[include]`` section may be used to control which services are exposed to particular user groups.
While service configuration files (.zcfg) may be located in a common repository or in arbitrary folders,
main.cfg files at different URLs may include different subsets of services. 

When the ZOO-Kernel handles a request, it will first check if there is an ``[include]`` 
section in main.cfg and then search for other .zcfg files in the current working directory (CWD) and 
subdirectories. If an included service happens to be located in a CWD (sub)directory, 
it will be published by its name in the ``[include]`` section. For example, the service
``/[CWD]/name/space/myService.zcfg``
would normally be published as name.space.myService, but if it is listed in the ``[include]`` section 
it will be published simply as myService: 

.. code-block:: guess
    :linenos:
    
    [include]
    myService =  /[CWD]/name/space/myService.zcfg

On the other hand, with

.. code-block:: guess
    :linenos:
    
    [include]
    myService =  /some/other/dir/myService.zcfg

there would be two distinct services published as myService and name.space.myService, respectively, 
with two different zcfg files.

.. note:: 
  As currently implemented, the ZOO-Kernel searches the CWD for the library files of 
  included services if the ``libPath`` parameter is not set.

      
.. rubric:: Footnotes

.. [#f1] If GET requests are passed through ``xlink:href`` to the ZOO-Kernel , the latter will execute the request the first time and store the result  on disk. The next time the same request is executed, the cached file will be used and this will make your process run much faster. If ``cachedir`` was not specified in the ``main.cfg`` then the ``tmpPath`` value will be used.
.. [#f2] Usefull when the :ref:`kernel-mapserver` is activated (available since ZOO-Project version 1.3.0).
.. [#f3] ZOO-Kernel and MapServer are sharing the same metadata for OGC Web Services if the :ref:`kernel-mapserver` is activated.