TITLE: FAQ
AUTHOR: jachym
DATE:
DESC: Frequently asked questions
FORMAT: raw
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            <h3>FAQ</h3>
            <h4>General questions</h4>
            <ul>

                <li><a href="#version">Which version of PyWPS should I
                    use?</a></li>
            <li><a href="#debug">How to debug PyWPS processes?</a></li>
            <li><a href="#commands">How run command line commands?</a></li>
            <li><a href="#gcommands">How run GRASS commands?</a></li>
            <li><a href="#doc">Where can I find documentation to process writing in general?</a></li>
            <li><a href="#dist">Why do I have to rename <code>processes/__init__.py-dist</code> and other files to <code>__init__.py</code>?</a></li>

            </ul>
            <h4>Error codes hints</h4>
            <ul>
                <li><a href="#noprocess">The process seems not to exist
                        (<code>InvalidParametrValue</code> code).</a></li>
                <li><a href="#gmalloc">The process returns <code>ERROR:
                            G_malloc: out of memory</code></a>.</li>

            </ul>

            <hr />
            <h4>General answares</h4>
            <dl>
                <dt><a name="version">Which version of PyWPS should I use?</a></dt>
                <dd>Currently, you should use the <a
                        href="http://pywps.wald.intevation.org/download/index.psp">latest stable version</a>.
                Older versions (1.0.0) are really outdated and you should
                better not use them.</dd>

                <dt><a name="debug">How to debug PyWPS processes?</a></dt>
                <dd>You have two possibilities: 
                    <ul>
                        <li>Run PyWPS from command line directly from
                            command line:
                            <pre>
jachym@mellon:~$ ./wps.py "&service=wps&version=0.4.0&request=execute&datainputs=input1,value1,input2,value2,..."
                            </pre>
                        </li>

                        <li>See error log file from your web server. I use
                            program <code>tail</code>:
                            <pre>
jachym@mellon:$ tail -f /var/log/apache/error.log |sed -e "s/\[.*\] //g"
PyWPS GCmd: r.rescale out=kat_dop_k_2004_1188372842 in=dop_k_2004_1188372842 to=0,255
to kat_dop_k_2004_1188372842[0,255]

PyWPS GCmd: r.support map=dop_k_2004_1188372842 title="drasil2" >&2
to kat_dop_k_2004_1188372842[0,255]

PyWPS GCmd: r.support map=kat_dop_k_2004_1188372842 title="drasil2" >&2
to kat_dop_k_2004_1188372842[0,255]

PyWPS ERROR: Could not perform command: r.support map=kat_dop_k_2004_1188372842 title="drasil2" >&2 in process K2O, method execute()
/home/bnhelp/pfwps/wps.py:79: DeprecationWarning: Non-ASCII character '\xc2' in file /usr/home/bnhelp/pfwps/pywps/processes/pf_interpolate_grass.py on line 51, but no encoding declared; see http://www.python.org/peps/pep-0263.html for details
  from pywps.processes import *
PyWPS GCmd: g.region rast=mask2004@medlov res=5 1>&2

....

                            </pre>
                        </li>
                    </ul>
                </dd>

                <dt><a name="commands">How to run command line commands?</a></dt>
                <dd>Use build-in method Cmd(string):
                    <pre>
                        self.Cmd("ogr2ogr .... ")
                </pre>
                </dd>
                <dt><a name="gcommands">How to run GRASS commands?</a></dt>
                <dd>Use build-in method GCmd(string):
                    <pre>

                        self.GCmd("r.surf.rst in=%s elev=dem" % (self.GetInputValue("dem")))
                </pre>
                </dd>
                <dt><a name="doc">Where can I find documentation to process
                        writing in general?</a></dt>
                <dd>
                    Try this sources of documentation:
                    <ul>
                        <li><code>doc</code> directory in PyWPS source
                            code. The best file for you is
                            <code>pywps-howto.pdf<code>. Also some examples
                                are there.</li>

                        <li><code>pydoc</code> command to <code></cocde>command.py</code> module
                        <pre>
                            cd pywps/Wps
                            pydoc process.py
                        </pre>
                        </li>
                        <li>There are example processes in
                            <code>pywps/processes/</code> directory. Try to
                            modify them to your needs.
                    </li>

                    </ul>
                </dd>
                <dt><a name="dist">Why do I have to rename <code>processes/__init__.py-dist</code> and other files to <code>__init__.py</code>?</a></dt>
                <dd>
                    <p>
                        The files
                    <ul>

                        <li><code>processes/__init__.py</code></li>
                        <li><code>etc/setup.py</code></li>
                        <li><code>etc/grass.py</code></li>
                    </ul>
                    do have <code>-dist</code> suffix. You have to rename
                    them and remove this suffix from the file name
                    (e.g. <code>processes/__init__.py-dist -&gt;

                        processes/__init__.py</code>) in order to get PyWPS
                    running and configured.
                    </p>
                    <p>
                        Why this? If you make some change to this
                        files (by tuning PyWPS), and later you would update
                        your installation of PyWPS, this original files
                        will be overwritten. In this case, only the
                        "<code>-dist</code>" will be overwritten and your
                        changes should be save.
                    </p>
                </dd>

            </dl>

            <hr />
            <h4>Error code hints</h4>
            <dl>
                <dt><a name="noprocess">The process seems not to exist
                        (<code>InvalidParametrValue</code> code).</a></dt>
                <dd>
                    Try this:
                    <ul>

                        <li>Is the project listed in GetCapabilities
                            responce?</li>
                        <li>Is the project registerd in
                            <code>pywps/processes/__init__.py</code> file?</li>
                    </ul>
                </dd>
                <dt><a name="gmalloc">The process returns <code>ERROR:
                            G_malloc: out of memory</code></a>.</dt>

                <dd>
                    You have to setup GRASS region, while operating with
                    raster maps.
                    <pre>
                        self.GCmd("g.region rast=input_map")
                    </pre>
                    or
                    <pre>
                        self.GCmd("g.region -d")
                    </pre>
                </dd>
            </dl>

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