.. _configuration.layers.examples:
Examples
========
The following are example configurations of layers in GeoWebCache.
Minimal configuration
---------------------
This example shows the absolute minimum information needed to configure a layer in GeoWebCache together with the assumptions made.
At the very least, GeoWebCache needs to know only two things to cache a layer:
#. The URL of the WMS server
#. The name of the layer as defined in the WMS
.. code-block:: xml
topp:states
http://demo.opengeo.org/geoserver/wms
In this case, the assumptions are:
#. WMS version 1.1.1 is used (``version=1.1.1``)
#. The layer will be valid for EPSG:4326 and EPSG:900913, with world extent (``srs=EPSG:4326``, ``srs=EPSG:900913``)
#. The layer name on the WMS is identical to the name of the layer as specified here (``layers=topp:states``)
#. The supported image format is PNG (image/png) and JPEG (image/jpeg) (``format=image/png``, ``format=image/jpeg``)
#. The default style used (``styles=``)
#. Exceptions are reported inside images (``exceptions=application/vnd.ogc.se_inimage``)
#. Requests using OpenLayers are made with ``transparent=true``
Explicit blob store configuration
---------------------------------
Unless otherwise specified, the tiles produced by a ``wmsLayer`` will be persisted to the cache defined by the default blob store.
The ``blobStoreId`` element allows to define an alternate blob store where to store the layer tiles.
See the :ref:`configuration.storage` page for more information on how to configure blob stores.
In this example, the layer is configured to use the ``myBlobStore`` blob store, which must be defined in the ``blobStores`` section
of ``gwcConfiguration`` with the same identifier.
.. code-block:: xml
myBlobStore
topp:states
http://demo.opengeo.org/geoserver/wms
Simple configuration
--------------------
The following is a more realistic but still simple example for configuring a layer in GeoWebCache.
In this case, the requirements are:
#. Combine two layers from a WMS, (``nurc:Img_Sample`` and ``topp:states``)
#. Name the layer ``img states`` (note the space in the name)
#. Set the projection to EPSG:4326
#. Limit the extent to the continental United States
#. Support only GIF
#. Draw the background color (where there is no data) in a shade of blue
#. Set the transparency to false
The resulting configuration would look like:
.. code-block:: xml
img states
Nicer title for Image States
This is a description. Fascinating.
image/gif
EPSG:4326
-129.6
3.45
-62.1
70.9
http://demo.opengeo.org/geoserver/wms
nurc:Img_Sample,topp:states
false
0x0066FF
.. note:: The reference to the gridset EPSG:4326 may look a bit mysterious. It is one of only two gridsets (the other being EPSG:900913) that is automatically defined inside GeoWebCache. Other gridsets will need to be configured manually. (Learn more about :ref:`concepts.gridsets` and :ref:`configuration.layers.projections`.)