| 1 | .. _using_zoo_from_osgeolivevm: |
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| 2 | |
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| 3 | Using ZOO from an OSGeoLive virtual machine |
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| 4 | ########################################### |
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| 5 | |
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| 6 | .. contents:: Table of Contents |
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| 7 | :depth: 5 |
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| 8 | :backlinks: top |
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| 9 | |
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| 10 | `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. |
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| 11 | |
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| 12 | ZOO Kernel Installation |
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| 13 | *********************** |
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| 14 | |
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| 15 | As already said in introduction, an OSGeoLive virtual machine image disk has |
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| 16 | been installed on your computer, allowing you to use ZOO Kernel in a development |
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| 17 | environment directly. Using a virtual machine image disk seems to be the simplest |
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| 18 | way to use ZOO Kernel and to develop ZOO Services locally, as we can ensure that |
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| 19 | everything requested for compiling C Services and running Python ones is available |
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| 20 | and ready to use. Every ZOO related material and source code have been placed in |
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| 21 | ``/home/user/zoows`` directory. We will work inside it during this workshop. As |
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| 22 | the binary version of ZOO Kernel is already compiled and stored in ``/home/user/zoows/sources/zoo-kernel``, |
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| 23 | you only have to copy two important files inside the ``/usr/lib/cgi-bin`` |
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| 24 | directory : ``zoo_loader.cgi`` and the ``main.cfg`` in order to make ZOO Kernel |
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| 25 | available, using the following commands : |
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| 26 | |
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| 27 | .. code-block:: guess |
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| 28 | |
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| 29 | sudo cp ~/zoows/sources/zoo-kernel/zoo_loader.cgi /usr/lib/cgi-bin |
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| 30 | sudo cp ~/zoows/sources/zoo-kernel/main.cfg /usr/lib/cgi-bin |
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| 31 | |
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| 32 | |
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| 33 | Please note that we will talk about ZOO Kernel or ``zoo_loader.cgi`` script without |
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| 34 | any distinction during this workshop. |
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| 35 | |
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| 36 | The ``main.cfg`` file contains metadata informations about the identification and |
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| 37 | provider but also some important settings. The file is composed of various sections, |
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| 38 | namely main, identification and provider per default. Obviously, you are free to add |
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| 39 | new sections to the file if you need them for a specific Service. Nevertheless, you |
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| 40 | have to know that the env and lenv sections name are used in a specific way. |
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| 41 | |
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| 42 | The env section lets you define environment variables that your Service requires |
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| 43 | during its runtime. For instance, if your Service requires to access to a X server |
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| 44 | running on framebuffer, then you will have to set the ``DISPLAY`` environnement |
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| 45 | variably, in this case you would add ``DISPLAY=:1`` line in your env section. |
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| 46 | |
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| 47 | As for the env section, there is the section lenv where specific informations about |
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| 48 | status informations of a running Service will be written by the ZOO Kernel or the |
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| 49 | ZOO Services. For instance, when your service failed, you can set the value for |
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| 50 | message in lenv to see it displayed in the Status node of the ExecuteResponse |
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| 51 | returned back to the client. If your service will take long time and can get |
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| 52 | informations about processing status, you can then set a value between 0 and 100 |
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| 53 | to status in lenv to represent the percentage completed of the running Service task, |
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| 54 | we will talk deeper about this later in this workshop. |
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| 55 | |
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| 56 | Please take a look to your local file ``main.cfg`` file. Three important parameters are commented bellow: |
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| 57 | |
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| 58 | - serverAddress : The url to access to the ZOO Kernel |
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| 59 | - tmpPath : The full path to store temporary files |
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| 60 | - tmpUrl : The url path relative to serverAddress to access temporary directory. |
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| 61 | |
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| 62 | The values of the main.cfg file used from the running virtual machine are the following : |
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| 63 | |
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| 64 | .. code-block:: guess |
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| 65 | |
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| 66 | serverAddress=http://localhost/zoo |
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| 67 | tmpPath=/var/www/temp |
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| 68 | tmpUrl=../temp/ |
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| 69 | |
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| 70 | You could have noticed that the tmpUrl is a relative url from ``serverAddress``, |
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| 71 | so it must be a directory. Even if ZOO Kernel can be used with the full url of |
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| 72 | the ``zoo_loader.cgi`` script, for better readability and fully functional ZOO Kernel, |
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| 73 | you have to modify the default Apache configuration in order to be able to use the |
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| 74 | http://localhost/zoo/ url directly. |
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| 75 | |
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| 76 | First, please create a ``zoo`` directory in the existing ``/var/www`` which is |
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| 77 | used by Apache as the ``DocumentRoot``. Then, please edit the ``/etc/apache2/sites-available/default`` |
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| 78 | configuration file and add the following lines after the ``Directory`` block related to ``/var/www`` directory : |
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| 79 | |
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| 80 | .. code-block:: none |
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| 81 | |
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| 82 | <Directory /var/www/zoo/> |
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| 83 | Options Indexes FollowSymLinks MultiViews |
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| 84 | AllowOverride All |
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| 85 | Order allow,deny |
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| 86 | allow from all |
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| 87 | </Directory> |
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| 88 | |
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| 89 | Now create a small ``.htaccess`` file in the ``/var/www/zoo`` containing the following lines: |
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| 90 | |
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| 91 | .. code-block:: guess |
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| 92 | |
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| 93 | RewriteEngine on |
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| 94 | RewriteRule call/(.*)/(.*) /cgi-bin/zoo_loader.cgi?request=Execute&service=WPS&version=1.0.0&Identifier=$1&DataInputs=sid=$2&RawDataOutput=Result [L,QSA] |
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| 95 | RewriteRule (.*)/(.*) /cgi-bin/zoo_loader.cgi?metapath=$1 [L,QSA] |
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| 96 | RewriteRule (.*) /cgi-bin/zoo_loader.cgi [L,QSA] |
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| 97 | |
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| 98 | For this last file to be taken into account by Apache, you must activate the |
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| 99 | rewrite Apache module by copying a load file as bellow : |
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| 100 | |
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| 101 | .. code-block:: guess |
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| 102 | |
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| 103 | sudo cp /etc/apache2/mods-available/rewrite.load /etc/apache2/mods-enabled/ |
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| 104 | |
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| 105 | Or using the ``a2enmod`` tool this way : |
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| 106 | |
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| 107 | .. code-block:: guess |
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| 108 | |
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| 109 | a2enmod rewrite |
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| 110 | |
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| 111 | Now you should be able to access the ZOO Kernel using a simplified by restarting your Apache Web server : |
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| 112 | |
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| 113 | .. code-block:: guess |
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| 114 | |
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| 115 | sudo /etc/init.d/apache2 restart |
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| 116 | |
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| 117 | |
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| 118 | Two other softwares form the OSGeoLive environment will be used during this workshop. |
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| 119 | MapServer will first be used to provide WFS input data for the ZOO Services we are |
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| 120 | going to develop. The MapServer dataset providen by Orkney (japanese regions polygons) |
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| 121 | will be passed to our service during `section 4 <http://zoo-project.org/trac/wiki/ZooWorkshop/FOSS4GJapan/CreatingOGRBasedWebServices#CallingthesinglegeometryservicesfromJavaScript>`__. |
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| 122 | |
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| 123 | OpenLayers library is also available on the OSGeoLive virtual machine image disk, |
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| 124 | and it will be used during `section 4 <http://zoo-project.org/trac/wiki/ZooWorkshop/FOSS4GJapan/CreatingOGRBasedWebServices#CallingthesinglegeometryservicesfromJavaScript>`__, for building a simple WPS client application able to query the newly developed ZOO Services. |
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| 125 | |
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| 126 | As we planned to use OGR C-API and Python module of the GDAL library, we will need |
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| 127 | the corresponding header files, libraries and associated files. Hopefully everything |
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| 128 | was already available per default and so ready to use on the OSGeoLive packaging. |
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| 129 | |
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| 130 | Testing the ZOO installation with GetCapabilities |
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| 131 | ************************************************* |
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| 132 | |
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| 133 | |
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| 134 | You can now simply query ZOO Kernel using the following request from your Internet browser: |
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| 135 | |
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| 136 | http://localhost/cgi-bin/zoo_loader.cgi?Request=GetCapabilities&Service=WPS |
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| 137 | |
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| 138 | You should then get a valid Capabilities XML document, as the following : |
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| 139 | |
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| 140 | .. image:: ./images/Practical-introduction-to-ZOO-2.png |
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| 141 | :width: 458px |
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| 142 | :height: 159px |
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| 143 | :align: center |
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| 144 | |
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| 145 | Please note that no Process node is returned in the ProcessOfferings section, as no |
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| 146 | ZOO Service is available yet. You can also proceed to a GetCapabilities request from |
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| 147 | the command line, using the following command: |
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| 148 | |
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| 149 | .. code-block:: none |
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| 150 | |
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| 151 | cd /usr/lib/cgi-bin |
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| 152 | ./zoo_loader.cgi “request=GetCapabilities&service=WPS” |
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| 153 | |
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| 154 | The same result as in your browser will be returned, as shown in the following screenshot: |
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| 155 | |
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| 156 | .. image:: ./images/Practical-introduction-to-ZOO-3.png |
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| 157 | :width: 395px |
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| 158 | :height: 251px |
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| 159 | :align: center |
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| 160 | |
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| 161 | Invoking ZOO Kernel from command line can be helpful during development process of new Services. |
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| 162 | |
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| 163 | Preparing your ZOO Services Provider directory |
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| 164 | ********************************************** |
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| 165 | |
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| 166 | In order to simplify the task, we will first comment the directory structure which |
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| 167 | should be used when creating a new Services Provider : |
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| 168 | |
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| 169 | - The main Services Provider directory including : |
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| 170 | |
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| 171 | - A ``cgi-env`` directory which will contain all the zcfg metadata files and the service shared object (C Shared Library or Python module) |
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| 172 | - The ``Makefile`` and the ``*c`` files needed to compile your Services Provider. |
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| 173 | |
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| 174 | Please create a ws_sp main Services Provider directory in the existing zoo-services one located in ``/home/user/zoows/sources/``, respecting the tree above . |
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| 175 | |
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| 176 | .. code-block:: guess |
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| 177 | |
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| 178 | mkdir -p /home/user/zoows/sources/zoo-services/ws_sp/cgi-env |
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| 179 | |
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| 180 | The Makefile and the code of the C and Python Service Shared Object will be detailed in the next sections. |
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| 181 | |
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