ZOO-Kernel Configuration

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. Every ZOO-Project related material and source code have been placed in /home/user/zoo-ws-2012 directory. We will work with file included in this directory during this workshop.

As explained later, the ZOO-Kernel may require to store temporary files in /var/www/temp. Depending on parameters set in the main.cfg, cache files would be located in the same directory.

No macro or processor named 'guess' found

General ZOO-Kernel settings are made in the main.cfg file located in the same directory as the ZOO-Kernel, so in /usr/lib/cgi-bin/. You can see a typical main.cfg content in the following:

.. code-block:: guess
    :linenos:
    [main]
    lang=en-US,fr-FR,ja-JP
    version=1.0.0
    encoding=utf-8
    serverAddress=http://localhost/zoo/
    dataPath=/var/www/data
    tmpPath=/var/www/tmp
    tmpUrl=../tmp
    cacheDir=/var/www/cache/
    mapserverAddress=http://localhost/cgi-bin/mapserv
    msOgcVersion=1.0.0
    [identification]
    title=The ZOO-Project FOSS4G 2012 Prague Workshop
    keywords=WPS,GIS,buffer
    abstract=ZOO-Project platform 2012 .See http://www.zoo-project.org for more informations
    accessConstraints=none
    fees=None
    [provider]
    positionName=Developer
    providerName=ZOO-Project
    addressAdministrativeArea=Lattes
    addressDeliveryPoint=1280 Av. des Platanes
    addressCountry=fr
    phoneVoice=False
    addressPostalCode=34970
    role=Dev
    providerSite=http://www.zoo-project.org
    phoneFacsimile=False
    addressElectronicMailAddress=gerald.fenoy@geolabs.fr
    addressCity=Lattes
    individualName=Gérald FENOY

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.

From the [main] section settings are as follow:

• lang: the supported languages separated by a coma (the first is the default one),
• version: the supported WPS version,
• encoding: the default encoding of WPS Responses,
• serverAddress: the url to access your ZOO-Kernel instance,
• dataPath: the path to store data files (when MapServer support was activated, this directory is used to store mapfiles and data).
• tmpPath: the path to store temporary files (such as ExecuteResponse when storeExecuteResponse was set to true),
• tmpUrl: a url relative to serverAddress to access the temporary file,
• cacheDir: the path to store cached request files [1] (optional),
• mapservAddress: your local MapServer address (optional),
• msOgcVersion: the version for all supported OGC Web Services output [2] (optional).

The [identification] and [provider] section are specific to OGC metadata and should be set [3].

Obviously, you are free to add new sections to this file if you need more. Nevertheless, you have to know that there is some specific names you should use only for specific needs: [env], [lenv] and [senv].

The env section is used to store specific environment variables you want to be set prior to load your Services Provider and run your Service. A typical example, is when your Service requires to access to a X server running on framebuffer, then you will have to set the DISPLAY environnement variable, in this case you would add DISPLAY=:1 line in your [env] section.

The lenv is used to store runtime informations automatically set by the ZOO-Kernel before running your service and can be accesses / updated from it:

• sid: the service unique identifier,
• status: the current progress value (value between 0 and 100, percent),
• cwd: the current working directory of the ZOO-Kernel,
• message: an error message when returning SERVICE_FAILED (optional),
• cookie: the cookie your service want to return to the client (for authentication purpose or tracking).

The senv is used to store session informations on the server side. You can then access them automatically from service if the server is requested using a valid cookie. The ZOO-Kernel will store on disk the values set in the senv maps, then load an dynamically added to the env stored in main.cfg:

• XXX: the session unique identifier where XXX is the name included in the

  returned cookie.

For instance, if you get the following in your Service source code [4] :

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

That means that the ZOO-Kernel will create a file sess_XXX1000000.cfg in the cacheDir and return the specified cookie to the client. Each time the client will request the ZOO-Kernel using the Cookie, it will automatically load the value stored before running your service. You can then easilly access this informations from your service source code. This functionality won't be used in the following presentation.

Testing the ZOO installation with GetCapabilities

You can request ZOO-Kernel using the following link from your Internet browser:

http://localhost/cgi-bin/zoo_loader.cgi?Request=GetCapabilities&Service=WPS

You should get a valid Capabilities XML document, looking like the following :

Please note that some Process node are returned in the ProcessOfferings section, as somes are available already on OSGeoLive DVD. You can also run a GetCapabilities request from the command line, using the following command:

cd /usr/lib/cgi-bin
./zoo_loader.cgi “request=GetCapabilities&service=WPS”

The same result as in your browser will be returned, as shown in the following screenshot:

Invoking ZOO Kernel from command line can be helpful during development process of new Services.

Footnotes