Metacat

Metacat's Use of Geoserver

==========================

user interface for interacting with the generated maps. You can use any

WMS-compatible client (e.g., ArcGIS, QGIS, JUMP, UDig, OpenLayers, Mapbender,

Map Builder).

you should, for security purposes, configure GeoServer so that it doesn't

use the default password. For instructions, please see

   :align: center

   A map generated by Metacat's GeoServer. Points and "bounding boxes"

   represent the geographic extent of datasets stored in the KNB Metacat repository.

styled using Styled Layer Descriptors (SLDs) and output as images (the default)

or raw vector data (GML or KML).

Currently, GeoServer can be used with the following limitations:

  fine-grained as Metacat's.

Metacat developers plan to continue extending and improving Metacat's mapping

capabilities. If you are interested in contributing to those efforts, or if

you are interested in learning more about the architecture and future plans for

team  (metacat-dev@ecoinformatics.org).

Installing and Configuring

--------------------------

NOT wish to run GeoServer, the deployment can be skipped, but any skins that

use maps will not render correctly. (NOTE: Geoserver recommends using a PermGen

space setting of at least 128MB.).

This includes a world-countries base layer and a default configuration that

is already aware of Metacat's spatial cache. The Metacat configuration interface

is used to configure GeoServer to use this shared data directory. To further

configure GeoServer, use the Web-based configuration utility,

(e.g., http://knb.ecoinformatics.org/knb/geoserver.jsp).

Common configuration tasks include:

* Adding a Map to a Web Page or Skin

* Configuring the Size and Initial Extent of the Map

* Configuring the Layout of the HTML Mapping Interface

* Configuring the "Select Location Drop-down Menu

* Configuring the Visual Portrayal of Geospatial Data (e.g., symbology and color)

* Adding Other Spatial Datasets to the Web Map

   GeoServer's Web-based administrative interface.

Note: Some configurations may need to be made to the XML files as well.

provides interface components or "widgets" (e.g., the map, a box zoom, layer

list, "Select Location" drop-down menu, scale bar, lat/long coordinates, and

a query form) that make it easy to deploy web-based mapping applications with

minimal coding.

Default configurations are in::

+----------------------------------+---------------+-------------------------------------------------------------+

| Document                         | Location      | Description                                                 |

+==================================+===============+=============================================================+

| The named location file          | locations.jsp | The list of pre-defined locations (name and lat/lon bounds) |

+----------------------------------+---------------+-------------------------------------------------------------+

| Main map rendering functions     | maps.js       | Defines the map, widgets and their behavior                 |

+----------------------------------+---------------+-------------------------------------------------------------+

| The rendered map and page layout | map.jsp       | Loads the map and controls the HTML layout of the widgets.  |

+----------------------------------+---------------+-------------------------------------------------------------+

NOTE: By default, the first time Metacat is restarted, it generates a

"spatial cache" containing geographic information about documents in its

repository. This default behavior is specified in lib/metacat.properties,

where the regenerateCacheOnRestart parameter is set to true. The information

in the spatial cache is stored in a GIS-compatible format (the ESRI Shapefile)

and consists of the document name and its geographic coverage. When documents

are inserted, deleted, and updated in the Metacat repository, Metacat

automatically syncs the spatial cache to reflect the changes. Because

generating the cache can take a considerable amount of time (several minutes

in the case of a few thousand documents), Metacat resets the

regenerateCacheOnRestart property to false after the spatial cache has been

generated. Note that if you upgrade or reinstall Metacat, the spatial cache

will be regenerated again.

Adding a Map to a Web Page or Skin

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To add a map to a Web page, simply include the map interface using an iframe::

          src="/knb/style/common/spatial/map.jsp">

the default map interface. If you plan to customize the map interface, copy

the map.jsp file into your skin's directory (either the default or

::

Configuring the Size and Initial Extent of the Map

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Before you configure the size and initial extent of the map, make sure that you

:doc:`configuration` for directions). Once the file has been copied, you can

modify the map's initial extent in: ``${skin.dir}/spatial/map.jsp``.

show the entire globe. The ``initMap()`` function should also be given the skin

name so that spatial search results can be correctly styled.

      function init() {

         var bounds = new OpenLayers.Bounds(-180,-90,180,90);

         // make the map for this skin

         initMap("<%=GEOSERVER_URL%>", "<%=SERVLET_URL%>", "default", bounds);

      }

  </script>

included in the ``map.jsp`` page.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

pages if desired. It contains the map, widgets and location dropdown list.

Configuring the "Select Location" Drop-down Menu

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The locations that appear in the "Select Location" drop-down menu are specified

spatial template into your skin directory. Each location is defined as an

HTML ``<option/>`` tag. Edit the value and label to edit or add new locations.

::

Configuring the Visual Portrayal of Geospatial Data (e.g., symbology and color)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Geospatial data sets are styled through the use of Styled Layer Descriptors

(SLD). The default SLDs used for the data points and data bounding boxes are in

``/lib/spatial/geoserver/data/styles/`` and are named data_points_style.sld and

data_bounds_style.sld, respectively.

Adding Other Spatial Datasets to the Web Map

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If you have vector GIS data sets, such as weather or topographical information,

on your server that you'd like to include in the interactive map, you must

first register the data set with GeoServer. After the data set has been

registered, you can add the layer to the map. You can also add spatial layers

that have been made publically available through WMS (There are hundreds of

spatial data sets available. Check out wms-sites.com for good catalog).

Instructions for adding publically available layers are included at the end

of this section.

To register the data set and add it to the map:

   and navigate to the "Data Stores" configuration page under ``Data > Stores``.

2. Create a new vector data source from a Shapefile in the “metacat” workspace.

   Creating a new shapefile using GeoServers web-based administrative interface.

   Add a new Layer from your new data source.

5. You should also define a spatial reference system (SRS) number for the new

   layer. Most lat/long data is "4326". If your data is in another projection,

   determine its spatial reference system using the help links provided.

   or create a new SLD to create a new style object and corresponding SLD

   (this option provides more control over the style).

7. Try out the styled data set as a WMS layer using a the Layer Preview.

   :align: center

   GeoServer's Layer Preview allows you to see an OpenLayer rendering of the new layer.

   (``style/common/spatial/map.js``) to your skin’s spatial directory.

9. Edit the init() method to include your new layer in the map – either as an

   overlay or as a base layer.

10. Point your browser to the map interface. Your new layer should appear with

Adding External Spatial Data Made Publically Available through WMS

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

There are hundreds of sources of spatial data made publically available

data sources to your map, add the layers in your skin’s ``spatial/map.js`` file.

Spatial Queries

---------------

To find out which documents in the Metacat repository lie in a specified

geographic region, query the spatial cache using Metacat's spatial_query action.

Metacat can perform any query supported by the WFS/WMS standards.

An example of a spatial query string is::

  http://localhost/knb/metacat?action=spatial_query&xmin=-117.5&xmax=-64&ymin=3&ymax=46&skin=default

Where ``xmin``, ``xmax``, ``ymin`` and ``ymax`` represent the western, eastern,

southern and northern bounding coordinates (the "bounding box"), respectively.

The spatial query action returns all documents that overlap or that are

contained inside the specified spatial coordinates. The result set is returned

as HTML using the style of the specified skin (in this example, default).