.. _scripting_overview:

Scripting Extension Overview
============================

The scripting extension provides a number of extension points called "hooks" 
throughout GeoServer. Each hook provides a way to plug in functionality via 
a script. See the :ref:`scripting_hooks` section for details on each of the
individual scripting hooks.

Scripts are located in the GeoServer data directory under a directory named
``scripts``. Under this directory exist a number of other directories, one 
for each scripting hook::

  GEOSERVER_DATA_DIR/
    ...
    scripts/
      apps/
      function/
      lib/
      wfs/
        tx/
      wps/
        
The ``apps`` directory provides an "application" hook allowing for one to 
provide a script invokable over http.

The ``function`` directory provides a Filter Function hook allowing to 
create new custom functions to be used for example in WFS/WMS filtering or in SLD 
expressions, see :ref:`filter_function`.

The ``lib`` directory is not a hook but is meant to be a location where 
common scripts/libraries may be placed. For instance this directory may be used as 
a common location for data structures and utility functions that may  be 
utilized across many different scripts.

.. note:: How the ``lib`` directory (or if it is utilized at all) is 
          language specific.

The ``wfs/tx`` directory provides a WFS Transactions hook allowing to intercept
WFS transaction.

The ``wps`` directory provides a Web Processing Service (WPS) process 
hook to contribute a process invokable via WPS.

See :ref:`scripting_hooks` for more details.

Creating scripts involves either creating a script in one of these hook directories or
creating it with web user interface.
New scripts are picked up automatically by GeoServer without a need to ever
restart the server as is the case with a pure Java GeoServer extension.