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1. The first allows the user to add a <FileSource
name="foo">/home/bar/baz/</FileSource> to the beginning of the file
and then in any of the symbolisers you can say:
<FooSymboliser base="foo" name="bridge">
It it will refer to the file /home/bar/baz/bridge.
2. The second allows you to create Datasource templates at the top
level, which can be used later in the actual layers like so:
<Map>
<Datasource name="db">
<Paramaeter name="host">/tmp</Parameter>
</Datasource>
<Layer name="lay">
<Datasource base="db">
<Parameter name="table">points</Parameter>
</Datasource>
</Layer>
</Map>
And the host parameter will be used in the layer.
3. The third adds the "base" parameter to the raster and shape input
plugins. All it does is specify a path to prefix to the filename prior
to using it. Together with the above feature it allows things like:
<Map>
<Datasource name="shapes">
<Paramaeter name="base">/home/foo/shapes</Parameter>
</Datasource>
<Layer name="lay">
<Datasource base="shapes">
<Parameter name="file">places</Parameter>
</Datasource>
</Layer>
</Map>
And it will use the shapefile /home/foo/shapes/places
See INSTALL file for installation instructions Mapnik is an OpenSource C++/Python toolkit for developing GIS (Geographic Information Systems) applications. At the core is a C++ shared library providing algorithms/patterns for spatial data access and visualization. Essentially a collection of geographic objects (map, layer, datasource, feature, geometry), the library doesn't rely on "windowing systems" and can be deployed in any server environment. It is intended to play fair in a multi-threaded environment and is aimed primarily, but not exclusively, at web-based development. High-level Python bindings (boost.python) facilitate rapid application development, targeting zope3, django etc. Mapnik is a free software and is released under LGPL (GNU Lesser General Public Licence) (see COPYING)