deegree Web Perspective View Service v2.4

2. Get deegree WPVS demo up and running

This chapter will give you a step by step introduction on how to install the deegree2 WPVS demo into a web server / servlet engine.

The web services of deegree2 are realized as Java modules controlled by one central servlet (a “dispatcher”). This servlet (and the Java modules) has to be integrated into your web server/servlet engine, this process is often addressed to as “deploying”. Most of the common web servers support servlet technology, making it possible to install deegree2 on a variety of web servers.

Although deegree2 can be installed on different web servers we recommend using the Apache-Tomcat 5.5 Servlet-Engine, due to its widespread use and its status as an open-source product¹. Furthermore, all deegree2 development is done with Tomcat 5.5, therefore you can be quite sure that if you're using a tomcat 5.5 and your webapp (the deegree2 WPVS) doesn't work, the problem is likely to be a configuration error and not an incompatibility error.

If you're using another web server / servlet engine please check it's documentation on how to deploy web services on it.

1. Pre-requisites

It is assumed that all necessary third party libraries are installed on your system. If you've not installed those libraries yet, please take a look at Appendix 6.2 Third party libraries for a complete list.

It is also assumed that you have a jdk (version 5 or higher) installed on your system and you have some standard tools like a plain text/xml editor and an unzip program.

VERY IMPORTANT: There are two very important issues you must resolve before you can use the deegree2 WPVS:

• Install the java 3D api, which can be downloaded from http://java.sun.com/products/java-media/3D/downloads/

• Make sure your graphics drive / gpu supports hardware 3D rendering.

2. Download

Visit http://www.deegree.org and download the WPVS zip file including a Web Perspective View Server package, a simple client and this documentation.

You can also checkout the latest deegree version from SVN (follow the instructions on the homepage). For more information on installing a WPVS from SVN please read chapter 5.3 “Installing the latest WPVS from SVN“ (not recommended as this is the developing version).

3. Tomcat integration

First download and install a current release of Tomcat, you'll also need the JDK 5 for this, the directory you've installed your tomcat in is traditionally called $CATALINA_HOME.

The next thing we have to do, is registering the deegree2 WPVS with your Tomcat, this means tomcat needs to be aware of the deegree's libraries ($WPVS_DIRECTORY), the handler (servlet) and the WPVS-configuration.xml file. Tomcat offers different mechanisms to achieve this.

This chapter will first explain the necessary steps to install the deegree-WPVS demo, which means you posses a deegree-wpvs.war.

1. Easy installation into Apache Tomcat

The easiest way to register deegree web services with Tomcat is to copy the deegree-wvps.war into the 'webapps' directory located in $catalina_home$. Afterwards restart Tomcat and the application will install automatically. The .war file, which is nothing more than a .zip file will be unziped into a new directory (named the same as the .war; in our case deegree-wpvs) under §catalina_home$/webapps. This directory will, in the following, be referenced as $WPVS_home$. Tomcat will be automatically pointed to the configuration files as it searches for a web.xml file in the WEB-INF directory.

2. Pointing Tomcat explicitly to application home directory

If you want to do the Tomcat installation process manually use the steps described in the following.

Unpack the deegree-wpvs.war to a directory (e.g. c:/deegree/webapps/deegree-wpvs) of your choice.

Afterwards Tomcat needs information about the root directory of the WPVS. The easiest way is to create a XML-file in the directory $TOMCAT_HOME$/conf/Catalina/localhost, named the same as the service e.g. deegree-wpvs.xml, and fill it with the following information

<Context docBase="c:/deegree/webapps/deegree-wpvs" path="/deegree-wpvs">

</Context>

where the docBase attribute reflects the physical location of the deegree service in the file system and the path attribute describes the virtual location of the main directory of the deegree web service. In the example, the root directory of the service is accessible at http://my.server.domain/deegree-wpvs/. For further information have a look at the Tomcat documentation included with the installation.

The name of the deegree-service directory is arbitrary whereas Tomcat definitely looks for a subdirectory WEB-INF (in capital letters – even on a Windows system) in the root directory. You will find this directory after tomcat automatically unpacked the war archive. Here the Deployment-Descriptor (web.xml) is located, which is analysed by Tomcat to identify the servlet(s) belonging to the application, their names, the parameters that are delivered to the servlet(s) and information about the existing access restrictions.

Before starting deegree WFS the following dataset entry in web.xml is essential:

<?xml version="1.0"?>

<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">

<web-app>

<display-name>deegree 2.2</display-name>

<description>deegree 2.2 OWS</description>

<servlet>

<servlet-name>owservice</servlet-name>

<servlet-class>org.deegree.enterprise.servlet.OGCServletController</servlet-class>

<init-param>

<param-name>services</param-name>

<param-value>wms,wpvs,wfs,wcs</param-value>

<description>list of supported services, e.g.: wfs,wms (comma separated)</description>

</init-param>

<!-- WMS Initializing Parameters-->

<init-param>

<param-name>wms.handler</param-name>

<param-value>org.deegree.enterprise.servlet.WMSHandler</param-value>

</init-param>

<init-param>

<param-name>wms.config</param-name>

<param-value>WEB-INF/conf/wms/wms_1_3_0_configuration.xml</param-value>

</init-param>

<!-- WPVS INITIALIZING PARAMETERS -->

<init-param>

<param-name>wpvs.handler</param-name>

<param-value>org.deegree.enterprise.servlet.WPVSHandler</param-value>

</init-param>

<init-param>

<param-name>wpvs.config</param-name>

<param-value>WEB-INF/conf/wpvs/wpvs_configuration.xml</param-value>

</init-param>

<!-- WFS INITIALIZING PARAMETERS -->

<init-param>

<param-name>wfs.handler</param-name>

<param-value>org.deegree.enterprise.servlet.WFSHandler</param-value>

</init-param>

<init-param>

<param-name>wfs.config</param-name>

<param-value>WEB-INF/conf/wfs/wfs_configuration.xml</param-value>

</init-param>

<!-- WCS INITIALIZING PARAMETERS -->

<init-param>

<param-name>wcs.handler</param-name>

<param-value>org.deegree.enterprise.servlet.WCSHandler</param-value>

</init-param>

<init-param>

<param-name>wfs.config</param-name>

<param-value>WEB-INF/conf/wcs/wcs_configuration.xml</param-value>

</init-param>

<load-on-startup>1</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>owservice</servlet-name>

<url-pattern>/services</url-pattern>

</servlet-mapping>

<welcome-file-list>

<welcome-file>index.html</welcome-file>

</welcome-file-list>

</web-app>

The name of the servlet and of the java-class representing the servlet should be indicated in the <servlet> tags. The servlet-name can be user defined, but care should be taken that the same name that is defined here is also used in the servlet-mapping. The servlet is located in the deegree2.jar library.

The tag <init-param> defines parameters that are analyzed by the servlet, while initializing. The transferred parameters are

• 'services': The value of this parameter contains a comma separated list of OWS that will be made available through the context. In the example a 'wpvs', 'wms', 'wfs' and 'wcs' is defined to be available (other possible values at the moment are e.g.: sos or csw).

• For each service listed in the 'service' init-param a handler class and a configuration file must be referenced.

• The name of the init-param for defining the handler starts with the service name ('wfs' in the example) followed by '.handler'. The value of this parameter is the name of the handler class to be used. It is possible to write a different class for this and reference it accordingly. As default ' org.deegree.enterprise.servlet.WPVSHandler' should be used.

• The name of the init-param for defining the main configuration file of a service also starts with the service name followed by '.config'. Notice that you can use a relative path to the configuration file starting at the WEB-INF directory of the context.

The tag <servlet-mapping> defines the alias name for the servlet. It is not necessary that the <servlet-name> and <url-pattern> are identical. <url-pattern> is the name for the parameter the servlet will be called through (part of the base-URL of the service that all requests have to use). Combined with the path settings in $TOMCAT_HOME$/conf/Catalina/localhost/deegree-wpvs.xml and respectively the name of the .war which you deployed in the $TOMCAT_HOME$/webapps (in our example deegree-wpvs) you should be able to point to your WFS (OWS) via the following URL: http://my.server.domain/deegree-wpvs/services?

4. Testing the installation

If everything went fine, deegree WPVS should be running by now with the sample data sets. Try the following request in your web browser:

http://localhost:8080/deegree-wpvs/services?SERVICE=WPVS&VERSION=1.0.0&REQUEST=GetCapabilities

This should provide a valid XML Capabilities file (if your browser asks for an application to open the file, try your browser again or any text editor). If you have installed the WPVS-demo or checked out the deegree sources from the CVS you are able to do just a little more though, check out the following GetView request, it will show you a nice 3D-View of Salt-lake city with some buildings:

http://localhost:8080/deegree-wpvs/services?BACKGROUND=cirrus&ELEVATIONMODEL=saltlakedem&CRS=EPSG:26912&YAW=0&REQUEST=GetView&OUTPUTFORMAT=image/png&DATETIME=2007-03-21T12:00:00&PITCH=20&DISTANCE=1550&VERSION=1.0.0&AOV=60&ROLL=0&POI=424994.4,4513359.9,1550&BOUNDINGBOX=424585.3,4512973.8,425403.5,4513746.0&SCALE=1.0&SPLITTER=BBOX&HEIGHT=600&DATASETS=Utah_Overview,satelite_images&STYLES=default&FARCLIPPINGPLANE=11000&WIDTH=800&EXCEPTIONFORMAT=INIMAGE

As this demo comes with a very simple example client, you can afterwards check, if this one works properly, too. Requesting this

http://localhost:8080/deegree-wpvs

url with your browser should start a page with a link to the client.

If all of this worked fine, your deegree WPVS and client is running and you can now add your own data. But before that, let’s first have a brief look at the architecture of deegree WPVS.

3. Configuring the WPVS

Although the deegree2 WPVS comes with some standard data of Salt-Lake city, you probably want to be able to get a perspective view of your own data. This chapter will explain the first step configuration possibilities of the WPVS and how you can make it aware of your data. Before jumping into the details, an overview of the architecture of the WPVS will be given, to let you understand the the different elements of a deegree2 WPVS configuration file.

1. Architecture

The WPVS (like all deegree2 web services) has a central configuration file, in which you define all parameters for controlling the web service. This file is an xml file which, includes the parameters mentioned in the OGC WPVS 1.0.0 specification for the Capabilities document, such as datasets and elevation models, but also additional parameters that are specific to deegree, as, for example, descriptions of data sources, copyright image and server settings. Figure 3.2 (on page 15) will give you an overview of the interaction between the wpvs-configuration elements and the wpvs.

2. Configuration file

The configuration file (located at $WPVS_home$/WEB-INF/conf/wpvs/
wpvs_configuration.xml) is, at the same time, a basis from which the WPVS Capabilites will be generated. Because of this, you'll find in the configuration two types ox XML elements: Those bound to OGC namespaces and those to the deegree2 WPVS namespace (e.g. deegreewpvs).

In the following, some of the basic elements of the configuration file will be described. Appendix A includes the complete configuration document. A more detailed description of the other elements is done in Chapter Fehler: Referenz nicht gefunden4 Fine-tuning the WPVS.

Figure 1: Schematic view of the Configuration of a Deegree2 WPVS.

After the root element, some deegree-WPVS-specific parameters are defined. These values can be used to fine tune your wpvs to the data you will be providing. The possible values are described in Chapter 4.1 Deegree parameters.

3. Service Parameters

The following elements in the configuration file (<ows:ServiceIdentification>, <ows:ServiceProvider> and <ows:OperationsMetadata>) are used to describe the service metadata. The elements are adopted from the WPVS 1.0.0 specification (OGC Commons) and therefore not described in this document. Most of the names of these elements are self explaining, for a description and possible values of these elements please read the WPVS-Specification, or take a look at the configuration file in Appendix 6.2 Complete deegree2 WPVS configuration

4. Datasets

After the deegree specific parameters and the dataproviders metadata elements the most important element is defined: <deegreewpvs:Dataset>. A Dataset can be understood as an encapsulation of the data which your serivce provides. There are two different kinds of <deegreewpvs:Dataset> elements in the deegree configuration:

• Structural datasets, define the layout of the WPVS

• Data providing datasets, define where and how data will be requested from different services.

Although a little confusing, there is a distinct difference in the two, the first kind of dataset is only accessible for the administrator of the WPVS to define the layout of the Service, whereas the other dataset is handed to requesting clients, so they can use it to request data, e.g. to insert in GetView – requests. In this chapter we will only discuss the second kind of datasets.

Each “data providing” <deegreewpvs:Dataset> must contain at least one <deegreewpvs:DataSource> (this can be understood as a link to a datasource). These datasources are only known to the administrator of the WPVS and will not be visible to any requesting clients.

The same way a <deegreewpvs:Dataset> can be understood as an encapsulation of data, a <deegreewpvs:DataSource> can be understood as a link to the location and the description of the capabilities of another webservice (e.g. a WCS, WMS or a WFS) which the WPVS will query to receive it's data from. Such data can be images, height values or 3D-objects. How these datasources are defined and which kind of datasources are available in deegree is described further below.

Another very important Element inside a (data providing or structural) Dataset is the <deegreewpvs:ElevationModel> element. Like a dataset it encapsulates a datasource, with the difference, that a datasource underneath an <deegreewpvs:ElevationModel> always returns elevationdata (e.g. height values) in contrast to a datasource which lies directly underneath a (data providing) <deegreewpvs:Dataset>, which always will provide geographic data in form of images or 3D-Objects.

More specific, the deegree 2 WPVS can display elevation data coming from vector sources (WFS) and or raster sources (WCS) as well as textural raster data (from a WMS or WCS), and three-dimensional object data (e.g. buildings) (from a WFS)

Some elements in the <deegreewpvs:Dataset> are not specifically defined by the WPVS 1.0.0 specification. This is true for the <deegreewpvs:DataSource> elements and the <deegreewpvs:ElevationModel>

To sum up, (also compare figure 3.2) data providing Datasets can encapsulate following data:

• Own data (referenced over a datasource):

  1. Texture from a WMS and/or WCS, for texturing the TIN

  2. Three-dimensional objects from a WFS

• Elevation data (referenced over an elevationmodel):

  1. As Point, Line, or Polygon (all 3D) from a WFS

  2. A raster (GeoTiff only)

A Dataset may or may not contain other (nested) Datasets. A typical Dataset has some optional and some mandatory elements. The following xml fragment shows all mandatory elements inside a <deegreewpvs:Dataset>:

<deegreewpvs:Dataset>

<deegreewpvs:Name>satellite_images</deegreewpvs:Name>

<deegreewpvs:Title>Metropolis Satelite photos</deegreewpvs:Title>

<deegreewpvs:Format>image/tiff</deegreewpvs:Format>

<ows:WGS84BoundingBox crs="urn:ogc:def:crs:OGC:2:84" dimensions="2">

<ows:LowerCorner>9.99 53.55</ows:LowerCorner>

<ows:UpperCorner>10.03 53.569</ows:UpperCorner>

</ows:WGS84BoundingBox>

<deegreewpvs:Identifier>second_dataset_identifier</deegreewpvs:Identifier>

<deegreewpvs:MinimumScaleDenominator>0.1</deegreewpvs:MinimumScaleDenominator>

<deegreewpvs:MaximumScaleDenominator>7000</deegreewpvs:MaximumScaleDenominator>

This could be a top (structural) Dataset, under which all other Datasets with actual data are defined. To point out the difference between a structural and an data providing Dataset, the same Dataset is displayed with an added datasource (<deegreewpvs:LocalWCSDataSource>) which gets it's data from a local wcs:

<deegreewpvs:Dataset>

<deegreewpvs:Name>satellite_images</deegreewpvs:Name>

<deegreewpvs:Title>Metropolis Satelite photos</deegreewpvs:Title>

<deegreewpvs:Format>image/tiff</deegreewpvs:Format>

<ows:WGS84BoundingBox crs="urn:ogc:def:crs:OGC:2:84" dimensions="2">

<ows:LowerCorner>9.99 53.55</ows:LowerCorner>

<ows:UpperCorner>10.03 53.569</ows:UpperCorner>

</ows:WGS84BoundingBox>

<deegreewpvs:Identifier>second_dataset_identifier</deegreewpvs:Identifier>

<deegreewpvs:MinimumScaleDenominator>0.1</deegreewpvs:MinimumScaleDenominator>

<deegreewpvs:MaximumScaleDenominator>7000</deegreewpvs:MaximumScaleDenominator>

<!-- Defining a datasource which will return raster data -->

<deegreewpvs:LocalWCSDataSource>

<deegreewpvs:Name>Metropolis_photos</deegreewpvs:Name>

<deegreewpvs:OWSCapabilities>

<deegreewpvs:OnlineResource xlink:type="simple" xlink:href="./wcs/wcs_configuration.xml"/>

</deegreewpvs:OWSCapabilities>

<deegreewpvs:MinimumScaleDenominator>

0.1

</deegreewpvs:MinimumScaleDenominator>

<deegreewpvs:MaximumScaleDenominator>

1000000

</deegreewpvs:MaximumScaleDenominator>

<deegreewpvs:FilterCondition>

<deegreewpvs:WCSRequest>

<![CDATA[VERSION=1.0.0&coverage=luftbild&TRANSPARENT=TRUE&FORMAT=tif&EXCEPTIONS=application/vnd.ogc.se_xml&crs=EPSG:31467]]>

</deegreewpvs:WCSRequest>

</deegreewpvs:FilterCondition>

</deegreewpvs:LocalWCSDataSource>

</deegreewpvs:Dataset>

It is often useful to create a new <deegreewpvs:Dataset> with each new <deegreewpvs:DataSource>, this way a client can make an accurate decision of which datasets are to be requested. Consider the following example: a WPVS only provides one dataset containing three different datasources, a) a WFSDataSource to display buildings 2) a WMSDataSource to show orthographic photos and 3) a WMSDataSource to show topographic maps of an area. Now a client can only request this one dataset and must always see the building the maps and the orthographic images although he might only be interested in the maps. Therefore it would be better to create three (nested) datasets each one containing it's own datasource (that is, a WFSDataSource, a WMSDataSource and another WMSDataSource), this way the client can select the one it wants to see. In the following section we described the different types of <deegreewpvs:DataSource> and their uses.

Inside the <deegreewpvs:Dataset> element the following metadata elements elements are mandatory:

• <deegreewpvs:Name>: The name by which a dataset shall be requested, it is good practice to choose unique names.

• <deegreewpvs:Title>: The title to be represented to a client to pick from

• <deegreewpvs:Format>: Mimetype describing the returned object of this dataset

• <ows:WGS84BoundingBox crs="urn:ogc:def:crs:OGC:2:84" dimensions="2">: The boudingbox in wgs84 for which this dataset is valid, it must contain following two child elements:

  • <ows:LowerCorner>: the wgs84 coordinates of the lowerleft corner of the boundingbox

  • <ows:UpperCorner>: the wgs84 coordinates of the upperright corner of the boundingbox

• <deegreewpvs:Identifier>: This identifier is specified by the WPVSreference, it should be unique in the total configuration. In the future clients may address this identifier to request the associated Dataset.

• <deegreewpvs:MinimumScaleDenominator>: Definining the minimum scale of the data for which this dataset is valid.

• <deegreewpvs:MaximumScaleDenominator>: Definining the maximum scale of the data for which this dataset is valid.

Except for these mandatory elements some optional child elements can be defined inside the <deegreewpvs:Dataset> element too. For the exact definitions and their possible values take a look at the complete configuration file displayed in Appendix 6.2 Complete deegree2 WPVS configuration.

5. DataSources

As mentioned above each data providing <deegreewpvs:Dataset> Element must also contain at least one <deegreewpvs:DataSource>. Although this is the most common use of DataSources, they are also found in <deegreewpvs:ElevationModel> elements, see Chapter 3.6 Elevation Models for an introduction of elevationmodels.

A <deegreewpvs:DataSource> can be understood as a link to the location and the description of the capabilities of another web service (e.g. a WCS, WMS or a WFS) which the WPVS will query to receive data. Datasources are only used internally by the WPVS and are never presented to requesting clients. Deegree2 can handle two different classes of datasources:

• Local DataSources: which can be configured to access your data via the deegree Framework. This means you don't have to set up a webservice inside a tomcat, but only need to supply a configuration file (or more exact an url embedded inside an <deegreewpvs:OnlineResource> element which points to the (local) configuration file), which describes the capabilities of your Local DataSource. Three different local datasources can be defined:

  • LocalWMSDataSource, providing raster data (as images), which can only be used as textures².

  • LocalWCSDataSource, providing raster data (as images), which can be used as height-values or textures.

  • LocalWFSDataSource, providing vector data embedded in xml. This data can be used as height-values or as 3D-Objects like buildings (e.g. city-GML)

• Remote DataSources: provides (among other things) a link to another Web Service (running inside a servlet engine) which can be contacted to receive data. Don't let the remote keyword confuse you, it only means the service has to be contacted via the http-protocol, but the service might as well run on your local machine. Deegree2 WPVS only knows two different remote datasources:

  • RemoteWMSDataSource, providing raster data (as images), which can only be used as textures.

  • RemoteWFSDataSource, providing vector data embedded in xml. This data can be used as height-values or as 3D-Objects like buildings (e.g. city-GML)

All <deegreewpvs:DataSource> elements have some (mandatory) common elements, which are exemplified in the following xmlfragment. This datasource defines a local datasource using data from a WCS:

<deegreewpvs:LocalWCSDataSource>

<deegreewpvs:Name>Metropolis_photos</deegreewpvs:Name>

<deegreewpvs:OWSCapabilities>

<deegreewpvs:OnlineResource xlink:type="simple" xlink:href="./wcs/wcs_configuration.xml"/>

</deegreewpvs:OWSCapabilities>

<deegreewpvs:MinimumScaleDenominator>

0.1

</deegreewpvs:MinimumScaleDenominator>

<deegreewpvs:MaximumScaleDenominator>

1000000

</deegreewpvs:MaximumScaleDenominator>

<deegreewpvs:FilterCondition>

<!--datasource specific-->

</deegreewpvs:FilterCondition>

</deegreewpvs:LocalWCSDataSource>

A <deegreewpvs:Name> element defines an identifier for the given DataSource, although this name is only known to the administrator (and is not provided to a client) it is good practice to make this name unique.

The <deegreewpvs:OWSCapabilities> element defines the link to the configuration document of the DataSource. For <deegreewpvs:Local***DataSource> this is a (relative or absolute) link pointing to a configuration file on the local filesystem. for <deegreewpvs:Remote***DataSource> this is a link to a GetCapabilities-request on a Webserver, this can be a webservice running on your localmachine (http://localhost/) or any other server. In the example above, the configuration can be found in the same file system, and is referenced as a relative path. For a remote DataSource you'd put the HTTP request pointing to the GetCapabilites request (resulting in an xml capabilities file) of the service in question.

The </deegreewpvs:MinimumScaleDenominator> and the <deegreewpvs:MaximumScaleDenominator> elements are equal to the elements of the <deegreewpvs:Dataset>. Resolution ranges may overlap or have gaps. They also need not match that of the parent Dataset. Note here the difference between those: The resolution range for a Dataset is an informative element, which is going to be shown in the capabilities of the WPVS. On the other hand, a resolution range of a data source is a configuration parameter, which only the service administrator has access to.

The <deegreewpvs:FilterCondition> element can define different child element. For a DataSource which handles raster data (a WMS or a WCS) this element defines parts of a wcs/wms request, for a DataSource handling vector data (WFS) this element defines a <wfs:query>. In the following the possible DataSources are shortly explained.

1. A WMS DataSource

A typical WMS DataSource is shown below:

<deegreewpvs:LocalWMSDataSource>

<deegreewpvs:Name>simple_wms</deegreewpvs:Name>

<deegreewpvs:OWSCapabilities>

<deegreewpvs:OnlineResource xlink:type="simple"

xlink:href="../wms/wms_configuration.xml" />

</deegreewpvs:OWSCapabilities>

<deegreewpvs:MinimumScaleDenominator>

0

</deegreewpvs:MinimumScaleDenominator>

<deegreewpvs:MaximumScaleDenominator>

5000000

</deegreewpvs:MaximumScaleDenominator>

<deegreewpvs:FilterCondition>

<deegreewpvs:WMSRequest>

<![CDATA[VERSION=1.1.1&LAYERS=LandUse,Roads&TRANSPARENT=true&FORMAT=image/png&EXCEPTIONS=application/vnd.ogc.se_inimage&BGCOLOR=0xffffff]]>

</deegreewpvs:WMSRequest>

</deegreewpvs:FilterCondition>

<deegreewpvs:TransparentColors>

<deegreewpvs:Color>#ffffff</deegreewpvs:Color>

</deegreewpvs:TransparentColors>

</deegreewpvs:LocalWMSDataSource>

Note that the Capabilities (OnlineResource element of OWSCapabilities) point to a file in the same file system. Note that this is, strictly speaking, not really the WMS capabilities, but the deegree WMS configuration. (You know from reading the deegree WMS documentation, that a WMS configuration looks very much like the WMS capabilities itself.)

The <deegreewpvs:FilterCondition> element includes a partial WMS request (defined inside the <![CDATA[]]> element) that will be used for the GetMap request. In the example above we are asking the GetMap to draw the layers 'LandUse' and 'Roads'. These layers must be defined by the WMS and it's your task to make sure the request is valid. (The WPVS will fill in the blanks, by adding missing parameters, e.g. width, height, bounding box, etc.)

Note the <deegreewpvs:TransparentColors> element, which define which colors in the GetMap image will be set to transparent. In the example above, all black pixels will be made fully transparent. This allows you to filter out pixels, making the texture associated with this service partially transparent.

A RemoteWMSDataSource looks just like a local one. The only difference is in the definition of the Capabilites:

<deegreewpvs:OWSCapabilities>

<deegreewpvs:OnlineResource xlink:type="simple"

xlink:href="http://localhost:8080/deegree-wms/services?

service=WMS&amp;request=GetCapabilities&amp;version=1.1.1" />

</deegreewpvs:OWSCapabilities>

This now points to the Capabilities document of the given webservice (localhost:8080) which is defined inside the href attribute. Note the different use of the ampersands inside the <![CDATA[]]> element and the <deegreewpvs:OnlineResource>.

2. A WCS DataSource

A WCS DataSource is almost every aspect identical to a WMS DataSource. The difference lies in the WCSRequest element of FilterCondition. This is obviously a fragment of a WCS request.

<deegreewpvs:LocalWCSDataSource>

<deegreewpvs:Name>simple_wms</deegreewpvs:Name>

<deegreewpvs:OWSCapabilities>

<deegreewpvs:OnlineResource xlink:type="simple"

xlink:href="../wms/config.xml" />

</deegreewpvs:OWSCapabilities>

<deegreewpvs:MinimumScaleDenominator>

0

</deegreewpvs:MinimumScaleDenominator>

<deegreewpvs:MaximumScaleDenominator>

5000000

</deegreewpvs:MaximumScaleDenominator>

<deegreewpvs:FilterCondition>

<deegreewpvs:WCSRequest>

<![CDATA[VERSION=1.0.0&coverage=city_layout&TRANSPARENT=TRUE&

FORMAT=png&EXCEPTIONS=application/vnd.ogc.se_xml&crs=EPSG:31466]]>

</deegreewpvs:WCSRequest>

</deegreewpvs:FilterCondition>

<deegreewpvs:TransparentColors>

<deegreewpvs:Color>#ffffff</deegreewpvs:Color>

</deegreewpvs:TransparentColors>

</deegreewpvs:LocalWMSDataSource>

3. A WFS DataSource

A WFSDatasource has great similarities with the above mentioned Datasources, there are however some differences. They can be explained by the nature of the data the different services return. It might therefore be useful to shortly describe the response of a WFS-GetFeature request.

The first difference between the services is, that the WFS returns vector data, while the other two services (WMS and WCS) return raster data. The result of a GetFeature request is a FeatureCollection in which different features are embedded. The common representation for features is XML. Inside these Features, GeometryProperties contain the “raw points” as geometry elements. An example for a feature, could be a building or a 3D label, but also height values as measure points of a terrain.

For the WPVS to use a WFSDataSource, it needs to tell the latter, the name of the GeometryProperties it wants to visualize. This can be done by defining a new element <deegreewpvs:GeometryProperty>. It contains an xpath expression which is used to select the GeometryProperty of the Features. This expression should be a qualified name, it's therefore up to you to make sure, that the prefix is bound to a namespace. The following XML-fragment is an example of a local WFS DataSource. In this example the xpath expression is app:geometry, with app: bound to the namespace http://www.deegree.org/app in the root element of the xml-document with the following assignment xmlns:app="http://www.deegree.org/app".

<deegreewpvs:LocalWFSDataSource>

<deegreewpvs:Name>buildings of metropolis</deegreewpvs:Name>

<deegreewpvs:OWSCapabilities>

<deegreewpvs:OnlineResource xlink:href="./wfs/wfs_configuration.xml" />

</deegreewpvs:OWSCapabilities>

<deegreewpvs:MinimumScaleDenominator>0.1</deegreewpvs:MinimumScaleDenominator>

<deegreewpvs:MaximumScaleDenominator>99992</deegreewpvs:MaximumScaleDenominator>

<deegreewpvs:MaxFeatures>150</deegreewpvs:MaxFeatures>

<deegreewpvs:GeometryProperty>app:geometry</deegreewpvs:GeometryProperty>

<deegreewpvs:ValidArea>

<gml:Polygon srsName="EPSG:31466">

<gml:outerBoundaryIs>

<gml:LinearRing>

<gml:coordinates cs="," decimal="." ts=" ">

3565687.9,5935846.7

3568308.4,5935846.7

3568308.4,5937998.9

3565687.9,5937998.9

3565687.9,5935846.7

</gml:coordinates>

</gml:LinearRing>

</gml:outerBoundaryIs>

</gml:Polygon>

</deegreewpvs:ValidArea>

</deegreewpvs:LocalWFSDataSource>

Note the similarities to other data sources: name, capabilities, scale range. The differences are explained below. Also note that a RemoteWFSDataSource is in every aspect similar to a local one.

Apart from the <deegreewpvs:GeometryProperty> element, the given LocalWFSDataSource example also introduces a new optional element which can be inserted into all DataSources (that is: remote and local, WMS, WCS and WFS) it is called: </deegreewpvs:ValidArea>. With this element you have the possibility of defining in which area the WPVS might find the data of the given DataSource. This prevents the WPVS from sending requests to the DataSource, if the ValidArea does not intersect with the visible area. Inside this element three different definitions are valid, either a <gml:Polygon> (displayed in this example), </gml:Surface> or <ows:BoundingBox>. For the exact definitions of these elements please take a look at the gml definitions and/or the ows definition.

There is yet one more element <deegreewpvs:MaxFeatures>, which cannot be added to the other two DataSources. It is a common use case, that you have different wfs-datasources, but you might not want to receive maxFeatures (defined in the wfs-configuration.xml) from each and every one of them. This element will allow you to configure the number of features for each of your wfs-datasources.

Allthough not displayed here, a <deegreewpvs:FilterCondition> element may be defined into a WFSDataSource too³. If it is defined, it is the skeleton of a WFS GetFeature query. The most important attributes here are 'typeName', which is also found in GetFeature requests, the srsName, which must match that of your data, and the namespace (xmlns:app) of your FeatureType. For more information on how to write <wfs:Query> take a look at your wfs documentation. For completion an example is given below:

<deegreewpvs:FilterCondition>

<wfs:Query handle="String"

typeName=""

featureVersion="String"

srsName="EPSG:31466"

xmlns:app="http://www.deegree.org/app">

<wfs:PropertyName>app:geometry</wfs:PropertyName>

<ogc:Filter>

<ogc:FeatureId fid="some_id" />

</ogc:Filter>

</wfs:Query>

</deegreewpvs:FilterCondition>

6. Elevation Models

Elevation models can be understood as a representation of the height values of a given area. As stated above the WPVS can handle two different representation of these height values, raster data and vector data (in form of measure points). To handle this data another element should be defined beneath a <deegreewpvs:DataSet> element in the configurationfile it is called: <deegreewpvs:ElevationModel>. It is comparable to a data providing <deegreewpvs:DataSet> element, it too encapsulates the data (which is used to create the terrain), it has a name, and must have at least one Datasource.

An elevation model element may have any number of data sources. However, the only valid types of datasources for elevation models are WFS and WCS. For a WCS data source, the returned image type must be of mimetype GeoTiff. Apart from this, datasource elements are not different to those described above. We now turn our attention to describing the two different elevationmodels with the different types of data sources.

1. An example: WCS-based Elevation Model

Although we say here “WCS-based” elevation model, no restrictions apply as to what type of data sources combination you may have in an elevation model. (Remember: WMS DataSources are not valid sources for elevation models.) You may combine a WFS and a WFC DataSource for, say, providing a coarse elevation model based on WFS points, and a high-resolution one based on a WCS. In practice, however, you'd only have either a WFS- or a WCS-based elevation model.

<deegreewpvs:ElevationModel>

<deegreewpvs:Name>dgm</deegreewpvs:Name>

<deegreewpvs:LocalWCSDataSource>

<deegreewpvs:Name>DEM-Model of Metropolis</deegreewpvs:Name>

<deegreewpvs:OWSCapabilities>

<deegreewpvs:OnlineResource xlink:type="simple" xlink:href="./wcs/config.xml"/>

</deegreewpvs:OWSCapabilities>

<deegreewpvs:MinimumScaleDenominator>0.1</deegreewpvs:MinimumScaleDenominator>

<deegreewpvs:MaximumScaleDenominator>1000</deegreewpvs:MaximumScaleDenominator>

<deegreewpvs:FilterCondition>

<deegreewpvs:WCSRequest>

<![CDATA[VERSION=1.0.0&coverage=dgm&TRANSPARENT=TRUE&FORMAT=GeoTiff&EXCEPTIONS=application/vnd.ogc.se_xml&crs=EPSG:31467&response_CRS=EPSG:31467]]>

</deegreewpvs:WCSRequest>

</deegreewpvs:FilterCondition>

<deegreewpvs:TransparentColors>

<deegreewpvs:Color>#000000</deegreewpvs:Color>

</deegreewpvs:TransparentColors>

</deegreewpvs:LocalWCSDataSource>

</deegreewpvs:ElevationModel>

There are no real surprises here. There are two things to bare in mind with elevationmodels, first the value of the <deegreewpvs:Name> element should be unique under all defined elevationmodels and secondly the returned image type of the WCS Datasource must be GeoTiff.

You now should be able to understand most of the configuration in the example file given in Appendix 6.2 Complete deegree2 WPVS configuration, and hopefully add your own DataSets to it. There are however a lot more options to configure, with which the behavior of the deegree2 WPVS is adopted to your specific needs. These will be discussed in the next chapter.

4. Fine-tuning the WPVS

We have so far described how you can configure your WPVS to show a perspective image in response to a GetView-request. The result might be quite satisfactory, but under most circumstances not good enough for you. The deegree2 WPVS has a way to fine tune your service appropriate to the data you want to present to a client. With the deegree2 WPVS it is possible for you to fine tune some settings according to your data and hardware. These possibilities are discussed in the following subsection.

Although we've said, all configuration is done in only one xml file, this isn't quite true. There are some other files (java property files), in which you can define the the rendering behavior of the java3D engine, as well as setting the colors of vector data geometries coming from a WFS. Before we take a look at those, we first describe the deegree parameters in the normal xml configuration file.

1. Deegree parameters

The deegree parameters element contains only child elements, which are specific for the deegree2 WPVS. The majority of these elements supply the WPVS with some kind of default value if the particular value isn't known or given. The responsible element in the configuration file is located directly under the root element and is called: <deegreewpvs:deegreeParams>. An example of a typical layout of this element is shown in the following xml code fragment:

<deegreewpvs:deegreeParams>

<deegreewpvs:DefaultOnlineResource

xlink:href="http://localhost:8080/deegree-wpvs/services"/>

<deegreewpvs:CacheSize>100</deegreewpvs:CacheSize>

<deegreewpvs:RequestTimeLimit>60</deegreewpvs:RequestTimeLimit>

<deegreewpvs:ViewQuality>0.95</deegreewpvs:ViewQuality>

<deegreewpvs:MaxViewWidth>1200</deegreewpvs:MaxViewWidth>

<deegreewpvs:MaxViewHeight>1000</deegreewpvs:MaxViewHeight>

<deegreewpvs:DefaultSplitter>QUAD</deegreewpvs:DefaultSplitter>

<deegreewpvs:RequestQualityPreferred>

false

</deegreewpvs:RequestQualityPreferred>

<deegreewpvs:MaxTextureDimension>8029</deegreewpvs:MaxTextureDimension>

<deegreewpvs:QuadMergeCount>10</deegreewpvs:QuadMergeCount>

<deegreewpvs:Copyright>

<!-- Text>Copyright 2006 lat/lon GmbH </Text -->

<deegreewpvs:ImageURL xlink:href="../images/deegree_alpha_unaliassed.png"

watermark="false" />

</deegreewpvs:Copyright>

<deegreewpvs:RequestsMaximumFarClippingPlane>

15000

</deegreewpvs:RequestsMaximumFarClippingPlane>

<deegreewpvs:NearClippingPlane>2</deegreewpvs:NearClippingPlane>

<deegreewpvs:MinimalTerrainHeight>55</deegreewpvs:MinimalTerrainHeight>

<deegreewpvs:MinimalWCSElevationModelResolution>

25

</deegreewpvs:MinimalWCSElevationModelResolution>

<deegreewpvs:ExtendRequestPercentage>1</deegreewpvs:ExtendRequestPercentage>

<deegreewpvs:BackgroundList>

<deegreewpvs:Background name="cloudy" href="images/background/cloudy.jpg" />

<deegreewpvs:Background name="sunset" href="images/background/sunset.jpg" />

</deegreewpvs:BackgroundList>

</deegreewpvs:deegreeParams>

The <deegreewpvs:DefaultOnlineResource/> is the URL by which the WPVS operations can be invoked. This parameter can be overwritten by the URLs defined in the request-definitions of the datasources (explained in the previous chapter).

The <deegreewpvs:CacheSize> parameter defines the size of the cache available to deegree-WPVS in megabyte (this does not affect the cache for data sources). This parameter is optional, its default value is 100 MB. (As of 2006-04-04, the cache is not activated.)

By <deegreewpvs:RequestTimeLimit> the maximum time span is defined after which a request has to be processed. If this value is exceeded the processing is canceled and an exception will be thrown. Its default value is 15 seconds.

Afterwards a <deegreewpvs:ViewQuality> parameter is defined, by which the quality of the created view can be controlled. Values for this parameter are between 0 (lowest quality) and 1 (best quality) with the default value being 0.95. This parameter is only used for image formats supporting different quality values (e.g. jpeg).

The following two parameters limit the maximum size of the response image that can be requested via a GetView request. It has to be considered that requesting large maps is very taxing on a server as the processing cost increases with the square of the border length of a map. For example, the creation a map having 1000x1000 pixel takes four times the memory than creating a map with size 500x500 pixel. Default is 1000 pixel for width and height.

The <deegreewpvs:DefaultSplitter> can be used to define a default splitter mode if no splitter was given inside a GetView request. A splitter is used to partially cut up the view frustum (which can be understood as the viewable area) into different resolutionstripes. This splitting is useful to create smaller individual request to the configured and requested datasets/elevationmodels and therefore acquiring more detailed images. The possible values for this element are QUAD or BBOX. A BBOX splitter doesn't actually cut up the viewable area, instead the bounding box of the requested area is sent to the datasets and elevationmodels, resulting in a poorly detailed response image. The default value for this element is QUAD.

Relevant to the <deegreewpvs:DefaultSplitter> element, is the following <deegreewpvs:RequestQualityPreferred> element. If the defaultsplitter is set to QUAD, the value of this element decides the number of (resolution) stripes that are created. A value of true, results in a very detailed response image, but a (much) longer processing time. Setting this value to false however, will result in a lesser quality response image but a faster processing time. If no value is given the default is false.

In some cases it can be very useful to set the size of a texture. For example if a specific server cannot respond images larger then 1024 pixels. The <deegreewpvs:MaxTextureDimension> element defines this request size. It is however (due to the nature of the wpvs) only possible to set one value for all DataSources. If this value is omitted or set higher then the size of the maximum texture size your gpu⁴ can handle, the latter size will be used.

Although the quattree-splitter is pretty good in calculatin the request envelopes. After it calculated these bboxes, it tries to merge them so fewer requests have to be made, hence resulting in a quicker processing of the data. Tests have proven however, that in some rare cases, it is useful not to merge quads. For this purpose the <deegreewpvs:QuadMergeCount> element can be used. We advise to set the value relatively low, it defaults to 10.

With the <deegreewpvs:Copyright> parameter it is possible to write a copyright remark in the lower left corner of each image. A copyright note can be either a text fragment or a (absolute or relative) reference to an image (e.g. c:/images/copyright.gif). For better effect, the image should be set to half-transparent. In case no Copyright parameter is supplied no output is produced.

The <deegreewpvs:RequestsMaximumFarClippingPlane> element gives you the opportunity to decide how far a requesting client can see. For very steep request, the maximum distance a GetView request should be able to see will lie somewhere in infinity, resulting in an immense amount of data to be requested. This parameter eliminates this behaviour, but be careful; setting a too small value will result in poor response images.

The <deegreewpvs:NearClippingPlane> element gives you the opportunity to decide how near a requesting client can see. If you set this value to high, the client will not see the near perimeter, if you set it to low e.g. much smaller then maxFarClippingPlane*0.001 some strange stripes in your images might be appear. This value defaults to 2.

For some data it is not necessary to have an elevation model, or the datasource defined in the elevationmodel doesn't always respond properly. In those cases it is useful to be able to define a minimal height value, for which you now the area you're presenting will never go beneath. This value can be defined in the <deegreewpvs:MinimalTerrainHeight>.

The next element <deegreewpvs:MinimalWCSElevationModelResolution> defines a way to set the minimal resolution a wcs based ElevationModel can handle. This is not to be confused with the <deegreewpvs:MaximumScaleDenominator> which defines a scale the datasource is valid for. In some cases it is more convenient to be able to define the minimal resolution of a wcs-request, resulting in smaller requests. This is particularly handy if the elevation model (build on a wcs-response) shows “rice-field” tableau's; setting this value to the appropriate resolution will resolve this problem.

With a WCS-DataSource as Elevation model, it can happen in a terrain with lots of mountains, that the requests don not perfectly overlap. Resulting in voids in the terrain. This phenomenon can be reduced by requesting a little larger Aera as strictly been calculated. The <deegreewpvs:ExtendRequestPercentage> element lets you decide the percentage of extension for each datasource-request. A good value lies somewhere around '3'. Be careful though, if you are using a WFS-Datasource for the terrain don't use this option.

The last parameter you can set is a list of background images which can be presented to the client. The <deegreewpvs:Background> elements inside the <deegreewpvs:BackgroundList> element define the locations of images, which can be rendered in the background of the scene.

2. Rendering options

All the options discussed in the previous chapter are very useful to define a certain behaviour of the deegree2 WPVS as a service. But so far nothing can be configured for the actual rendering process. To accommodate you to get the most beautiful images out of your hardware, another file can be edited. This file is a java properties file with different key value pairs defined inside it. You can find a copy of default used values in Appendix 6.2 Rendering configuration options.

If you want to change any of these values, just put a copy of this file into the root directory of your webapp with the name rendering_options.properties. The WPVS will first try to read this location and (if nothing was found) will use the one inside the deegree package. While a lot of combinations are possible and quite some background knowledge is necessary to understand the values in this file, we will not try to describe them, but leave it to the interested reader to do some self investigation. The key value pairs are all very well documented though and they can be used to get first impression what the different parameters are able to do. So if you're not content with the result of your response image (e.g. it's to dark, bright etc.) take a look in this file and try adjusting any or some of these parameters.

3. Material properties

There is one final possibility to adjust the outcome of the rendered GetView-response image. Again it is a java.propertie file, but it now only is valid for the 3D-Objects coming from a WFS-DataSource underneath a dataset element. The file is called material.properties and can be used to set the visual behaviour of the geometries which are created out of a GetFeature response from a WFS. Once again a complete file is given in Appendix 6.2 Material properties file, and if you want to adjust these values you can (again) place a copy (with the adjusted values) in the root directory of your web application with the name material.properties. The values in this file will only be used if the CityGML Geometry (which is probably the Geometry inside the Features) has no value defined for parameter.

Most of the parameters in this property file take a three color attributes in r g b (red, gree, blue), which means you can put in values between 0 and 1, each value separated with a blank space in between. So for example if you want to make all the surfaces of your 3D-Objects that do not supply a diffusecolor attribute them selves, will show up green you would adjust the diffusecolor value inside the properties file as follows:

diffusecolor=0 1 0

5. Different ways to install deegree2 WPVS into Tomcat

In this chapter some additional ways (other than using the manager) are described to install your deegree2 WPVS into a tomcat servlet engine.

1. Manually installing the demo in Tomcat

If you want to install the deegree2 WPVS demo into Tomcat manually, the first thing you have to do is to tell Tomcat about the root directory of your WPVS (and other deegree web services if installed in the same server context). This has to be done by first unzipping the deegree-wpvs.war file to a location (e.g. a directory called deegree-wpvs) of your choice and afterwards creating an additional .xml file (for example deegree-wpvs.xml) in $CATALINA_HOME/conf/Catalina/localhost/ with the following <Context> tag in it (remember $CATALINA_HOME is the install directory of your Apache Tomcat):

<Context path="/deegree-wpvs"

docBase="$WPVS_DIRECTORY/deegree-wpvs"

crossContext="false"

debug="0" reloadable="false"/>

The path attribute describes the virtual location (the context path) of the deegree web service. In the example, the service is accessible at http://localhost:8080/deegree-wpvs/. The docBase attribute reflects the physical location of the deegree service in the file system. The other attributes and their values are essential for good performance.

2. Installing a single deegree.jar

As stated before there are several ways to install a web application into the Tomcat servlet engine, if you just posses the deegree.jar some work is coming up to you. Let us first take a look at the Configuration file you are going to have to create, and after that take a look at the two deploy possibilities of the Tomcat manager and the manual deployment.

1. Tomcat configuration files

If you want to build a web application from scratch, the first thing you have to do, is to create a directory (let's call it $DEEGREE_WEBAPP) in which your web application will reside. In this directory Tomcat will look for a (mandatory) subdirectory WEB-INF/ (in capital letters – even on a Windows system), so we are going to have to create this directory too. In WEB-INF a Deployment-Descriptor with the filename web.xml is located. This file is analyzed by Tomcat to identify the servlet(s) belonging to the application, their names, the parameters that are delivered to the servlet(s) and information about the existing access restrictions. The description of all allowed values is out of the scope of this document, but the (for the deegree-WPVS) necessary values are listed in the following:

<?xml version="1.0" encoding="ISO-8859-1"?>

<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN"

"http://java.sun.com/j2ee/dtds/web-app_2_2.dtd">

<web-app>

<servlet>

<servlet-name>services</servlet-name>

<servlet-class>

org.deegree.enterprise.servlet.OGCServletController

</servlet-class>

<init-param>

<param-name>services</param-name>

<param-value>wpvs</param-value>

</init-param>

<init-param>

<param-name>WPVS.handler</param-name>

<param-value>org.deegree.enterprise.servlet.WPVSHandler</param-value>

</init-param>

<init-param>

<param-name>WPVS.config</param-name>

<param-value>WEB-INF/conf/wpvs/wpvs_configuration.xml</param-value>

</init-param>

<load-on-startup>1</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>services</servlet-name>

<url-pattern>/services</url-pattern>

</servlet-mapping>

</web-app>

The name of the servlet and of the java-class representing the servlet should be indicated in the <servlet> tags. The servlet-name can be user defined, but care should be taken that the same name that is defined here is also used in the <servlet-mapping> tag.

The servlet 'org.deegree.enterprise.servlet.OGCServletController' is located inside the deegree.jar.

The tag <init-param> defines parameters that are analyzed by the servlet, while initializing. The transferred parameters are

• 'services': The value of this parameter contains a comma separated list of OWS that will be made available through the context. In the example only a WPVS is defined to be available (other possible values at the moment could be: WFS, WMS, WCS, SOS and CS-W).

• For each service listed in the 'service' init-param a handler class and a configuration file must be referenced.

• The <param-name> of the <init-param> for defining the handler starts with the service name (WPVS in the example) followed by '.handler'. The <param-value> of this parameter is the name of the handler class to be used. It is possible to write different classes for this purpose and reference them accordingly. As a default 'org.deegree.enterprise.servlet.WPVSHandler' (which is available inside the deegree2.jar) could be used.

• The <param-name> of the <init-param> for defining the location of the WPVS-configuration file (which has nothing to do with the Tomcat configuration files) also starts with the service name followed by '.config'. Notice that you can use a relative path to the configuration file starting at the WEB-INF directory of the context.

• The tag <servlet-mapping> defines the alias name for the servlet. It is not necessary for the <servlet-name> and <url-pattern> to be identical. <url-pattern> is the name for the parameter the servlet will be called through (part of the base-URL of the service that all requests have to use), in our example this will be http://localhost:8080/deegree-wpvs/services?

The next step is to create the directory for the WPVS-configuration, at excactly the location you've defined in the web.xml file. Because we've defined <param-value>WEB-INF/conf/wpvs/wpvs_configuration.xml</param-value> our WPVS configuration file must be located into the directory $DEEGREE_WEBAPP/WEB-INF/conf/wpvs/. We won't worry about the layout of this file now, but we'll get back to it in Chapter 3 Configuring the WPVS.

Figure 2: Directory tree of the deegree web application

You are now ready to deploy your deegree-WPVS to your Tomcat. Again you can use the two ways described above (see and Manually installing the demo in Tomcat), with the only difference that you just specify your sole directory $DEEGREE_WEBAPP/ instead of the file $WPVS_DIRECTORY/deegree.war.

3. Installing the latest WPVS from SVN

If you don't have deegree2 WPVS demo or a deegree.jar yet, there is a third way to deploy a deegree2 WPVS to your Tomcat; you can use the sources from the SVN repository. This documentation will not describe how to checkout deegree from SVN⁵ but solely the deploy mechanism available to you. This mechanisms uses the ant tool, which can be downloaded from http://ant.apache.org/. In order for this tool to work with your tomcat installation, you are going to have to install the extra package apache-tomcat-5.5-deployer.

If you've checkout the current deegree sources, (let's say in the directory $DEEGREE_SRC), there are two things you have to do, first of all edit the file $DEEGREE_SRC/webapps/deegree/WEB-INF/web.xml so that it contains only those element tags needed for the WPVS (for an example and explanation see the chapter Tomcat configuration files).

After that you must open the file $DEEGREE_SRC/build.properties with your favorite text/xml editor. In this file locate the following lines and adopt them to your system, (the values are described in the previous chapters). Only those lines you should edit are shown here, you should leave the others unchanged.

# Tomcat 5.5 home (needed for catalina-ant.jar)

tomcat.home=$CATALINA_HOME

tomcat.host=localhost

tomcat.port=8080

tomcat.username=tomcat

tomcat.password=tomcat

You are done editing files and ready to deploy your wpvs into your Tomcat. To do this, open a command line (in windows click “start->run” and type 'cmd.exe') and now change the working directory (with the cd command) to $DEEGREE_SRC. If all is well you can enter the following command: “ant deploy”, which will use your Tomcat manager to install the deegree2 WPVS into your web engine.

6. Extras

   1. adding the optional Get3DFeatureInfo-Request

This feature is still under construction!

As in the GetFeatureInfo-Request of the WMS, one can also query informations of three-dimensional objects displayed by the deegreeWPVS. This operation is not described in the draft version of the WPVS specification, but it is additionally implemented in the deegree WPVS. To use this optional method one has to adapt the configuration file of the WPVS:

First you have to register the Get3DFeatureInfo operation - insert the following xml fragment in the operation metadata section:

<ows:Operation name="Get3DFeatureInfo">

<ows:DCP>

<ows:HTTP>

<ows:Get xlink:href="http://127.0.0.1:8080/deegree-wpvs/services">

<ows:Constraint name="operation_dcp_http_get_constraint_name_String">

<ows:AllowedValues>

<ows:Value>operation_dcp_http_get_constraint_owsValue_String</ows:Value>

</ows:AllowedValues>

<ows:DefaultValue>String</ows:DefaultValue>

</ows:Constraint>

</ows:Get>

</ows:HTTP>

</ows:DCP>

<ows:Parameter name="Get3DFeatureInfoOperation_parameter_name_String">

<ows:AllowedValues>

<ows:Value>operation_parameter_owsValue_String</ows:Value>

</ows:AllowedValues>

<ows:DefaultValue>String</ows:DefaultValue>

</ows:Parameter>

<ows:Constraint name="operation_constrain_name_String">

<ows:AllowedValues>

<ows:Value>operation_constrain_owsValue_String</ows:Value>

</ows:AllowedValues>

<ows:DefaultValue>String</ows:DefaultValue>

</ows:Constraint>

</ows:Operation>

Depending on your installation you maybe have to match the attribute xlink:href in the Get element. Then make sure that the Dataset(s) you want to query have the attribute queryable=”1”. Otherwise you get no access to the associated features.

Now the Get3DFeatureInfo-Request can be used. The parameter needed to this operation are described as follows:

• YAW, PITCH, ROLL, AOV, DISTANCE, STYLES, WIDTH, HEIGHT, CRS, BOUNDINGBOX, OUTPUTFORMAT, EXCEPTIONS, DATASETS, POI: general information of the view

• QUERY_DATASETS: names the dataset(s) to query

• FEATURE_COUNT: sets the maximal number of features contained in the response

• I, J: specifies the coordinates (pixel) of the point of interest in the view

• DEPTH: limits the distance of the geometry of the request

2. teaching the WFS the Keyhole Markup Language (KML)

The Keyhole Markup Language (KML) is a file format for exchanging of three-dimensional geographical data. It is used i.e. by GoogleEarth. The deegree WFS used by a deegree WPVS as WFSDatasource can return features in KML. Only adjust the configuration file of the WFSDatasource. The format (text/xml; subtype=kml) in the OutputFormat element must be added in the feature type list section. This element has been extended by three additional attributes, providing the option to apply XSL-processing to responses.

<wfs:Format deegree:outFilter="xsl/wpvs2kml.xsl"

deegree:inFilter="xsl/dummy.xsl"

deegree:schemaLocation="http://code.google.com/apis/kml/schema/kml21.xsd"> text/xml; subtype=kml</wfs:Format>

• The deegreewfs:outFilter must be set to the XSL-script wpvs2kml.xsl. It transforms the document that will be produced as output in KML.

• The deegreewfs:inFilter must be set to the XSL-script dummy.xsl. It is necessary for transforming requests to match the internal (default) GML schema.

• The deegreewfs:schemaLocation shows the location of the schema describing the KML-documents produced by the outFilter-script.

Make sure that the WFS is running in your tomcat. Chapter 5.2.1, Tomcat configuration files, describe how to register a service. In the list of the available services 'wfs' must be noticed. Furthermore the following parameters must be set:

<init-param>

<param-name>wfs.handler</param-name>

<param-value>org.deegree.enterprise.servlet.WFSHandler</param-value>

</init-param>

<init-param>

<param-name>wfs.config</param-name>

<param-value>WEB-INF/conf/wfs/LOCALWFS_Capabilities.xml</param-value>

</init-param>

The parameter wfs.config must point at the configuration file of the WFS. Having restarted the Tomcat you can set the parameter outputFormat in your GetFeature-Requests to text/xml; subtype=kml.

1. Third party libraries

deegree uses and redistributes the following third party libraries:

JTS - Java Topology Suite:

http://www.vividsolutions.com/jts/jtshome.htm

The JTS Topology Suite is an API of 2D spatial predicates and functions. It has the following design goals:

• JTS conforms to the Simple Features Specification for SQL published by the Open GIS Consortium

• JTS provides a complete, consistent, robust implementation of fundamental 2D spatial algorithms

• JTS is fast enough for production use

• JTS is written in 100% pure JavaTM

JTS is open source (under the LGPL license)

PostGreSQL/Postgis JDBC Driver

PostGIS adds support for geographic objects to the PostgreSQL object-relational database. In effect, PostGIS "spatially enables" the PostgreSQL server, allowing it to be used as a backend spatial database for geographic information systems (GIS), much like ESRI's SDE or Oracle's Spatial extension. PostGIS follows the OpenGIS "Simple Features Specification for SQL" and will be submitted for conformance testing at version 1.0.

PostGIS has been developed by Refractions Research Inc as a research project in open source spatial database technology. PostGIS is released under the GNU General Public License. We intend to continue development as time and resources permit. Our list of future projects includes enhanced technology for data loading and dumping, user interface tools for direct data access and manipulation, and support for advanced topologies at the server side, such as coverages, networks, and surfaces.

ACME Java - Software

http://www.acme.com/java/software/

All of this is completely free for any use, educational commercial or whatever. I do have to earn my grocery money, though. I'm available for consulting, and would be very interested in work that builds on these Java utilities. And of course if your company wants to sponsor ACME Labs with equipment or large cash donations, that would be ok too!

This software is written for JDK1.0.2, but with one exception it also compiles under JDK1.1. You'll get a lot of warnings about deprecated methods, but it'll work. The only exception is StubToolkit, where I had to use some of the internal sun.* classes.

Apache Batik

http://xml.apache.org/batik/index.html

Batik is a Java(tm) technology based toolkit for applications or applets that want to use images in the Scalable Vector Graphics (SVG) format for various purposes, such as viewing, generation or manipulation.

• Applications of Batik

• The SVG Specification

• What is Batik's Implementation Status?

• Downloading the Batik distribution (source and binary)

• Examples of projects and products using Batik

The project's ambition is to give developers a set of core modules which can be used together or individually to support specific SVG solutions. Examples of modules are the SVG Parser, the SVG Generator and the SVG DOM. Another ambition for the Batik project is to make it highly extensible (for example, Batik allows the developer to handle custom SVG tags). Even though the goal of the project is to provide a set of core modules, one of the deliverables is a full fledged SVG browser implementation which validates the various modules and their inter-operability.

Jakarta Commons

http://jakarta.apache.org/commons/index.html

The Commons is a Jakarta subproject focused on all aspects of reusable Java components.

The Jakarta Commons project is composed of two parts:

• The Commons Proper - A repository of reusable Java components.

• The Commons Sandbox - A workspace for Java component development.

Apache log4j

Apache log4j is a logging api provided by the apache project.

2. Complete deegree2 WPVS configuration

<?xml version="1.0" encoding="UTF-8"?>

<deegreewpvs:WPVS_Configuration xmlns:deegreewpvs="http://www.deegree.org/wpvs"

xmlns:gml="http://www.opengis.net/gml" xmlns:ows="http://www.opengis.net/ows"

xmlns:wpvs="http://www.opengis.net/wpvs" xmlns:xlink="http://www.w3.org/1999/xlink"

xmlns:app="http://www.deegree.org/app" xmlns:wfs="http://www.opengis.net/wfs" version="1.0.0"

updateSequence="String">

<!-- ================================================================== -->

<!-- DEEGREE PARAMS SECTION -->

<!-- ================================================================== -->

<deegreewpvs:deegreeParams>

<deegreewpvs:DefaultOnlineResource xlink:href="http://localhost:8080/deegree-wpvs/services" />

<deegreewpvs:CacheSize>100</deegreewpvs:CacheSize>

<!-- The time a request has, before it gets terminated -->

<deegreewpvs:RequestTimeLimit>60</deegreewpvs:RequestTimeLimit>

<!-- for jpeg (in the future tiff) encoding -->

<deegreewpvs:ViewQuality>0.95</deegreewpvs:ViewQuality>

<!-- maximum view width that can be requested. default = 1200 -->

<deegreewpvs:MaxViewWidth>1200</deegreewpvs:MaxViewWidth>

<!-- maximum view height that can be requested. default = 1000 -->

<deegreewpvs:MaxViewHeight>1000</deegreewpvs:MaxViewHeight>

<!-- what kind of splitter to use if the no splitter is requested (can be BBOX or QUAD) -->

<deegreewpvs:DefaultSplitter>QUAD</deegreewpvs:DefaultSplitter>

<!-- which is printed in the lowerleft corner of the GetView (image) response -->

<deegreewpvs:Copyright>

<!-- Text>Copyright 2006 lat/lon GmbH </Text -->

<deegreewpvs:ImageURL xlink:href="./images/copyright/logo-deegree_alpha_unaliassed.png"

watermark="false" />

</deegreewpvs:Copyright>

<!-- If the splitter is QUAD should it generate lots of request (e.g higher quality) or fewer

requests (e.g. lower Quality but quicker processing time)-->

<deegreewpvs:RequestQualityPreferred>false</deegreewpvs:RequestQualityPreferred>

<!-- What is the maximum requestable far clippingplane in meters-->

<deegreewpvs:RequestsMaximumFarClippingPlane>150000</deegreewpvs:RequestsMaximumFarClippingPlane>

<!-- The minimalheight of the terrain, if no fitting dgm is found all points will be set to this

height, defaults to 0-->

<deegreewpvs:MinimalTerrainHeight>1455</deegreewpvs:MinimalTerrainHeight>

<!-- If a wcs is used for the elevationmodel, the following value defines the minimal resolution

in meters, which means a wcs-request can not have a smaller resolution as this value. This

helps removing typical "ricefield" forms in the landscape. -->

<deegreewpvs:MinimalWCSElevationModelResolution>

40

</deegreewpvs:MinimalWCSElevationModelResolution>

<!-- If a wcs is used for the elevationmodel, it is often possible to see a little rim between

the request tiles. This value defines a percentage to add to the request, resulting in

overlapping request thus removing the space between tiles. valid values are 0 <= x <= 100 -->

<deegreewpvs:ExtendRequestPercentage>6</deegreewpvs:ExtendRequestPercentage>

<!-- A list of the images a client can request to be rendered in the background -->

<deegreewpvs:BackgroundList>

<deegreewpvs:Background name="cloudy" href="images/background/cloudy.jpg" />

<deegreewpvs:Background name="cirrus" href="images/background/cirrus.jpg" />

<deegreewpvs:Background name="sunset" href="images/background/sunset.jpg" />

</deegreewpvs:BackgroundList>

</deegreewpvs:deegreeParams>

<!-- ================================================================== -->

<!-- SERVICE IDENTIFICATION SECTION -->

<!-- ================================================================== -->

<ows:ServiceIdentification>

<ows:Title>WPVS for Salt Lake City, Utah -USA</ows:Title>

<ows:Abstract>

A WPVS which creates a perspective view of the Downtown region of Salt Lake City, Utah - USA

</ows:Abstract>

<ows:Keywords>

<ows:Keyword>WPVS</ows:Keyword>

<ows:Type>String</ows:Type>

</ows:Keywords>

<ows:ServiceType>WPVS</ows:ServiceType>

<ows:ServiceTypeVersion>1.0.0</ows:ServiceTypeVersion>

<ows:Fees>none</ows:Fees>

<ows:AccessConstraints>none</ows:AccessConstraints>

</ows:ServiceIdentification>

<!-- ================================================================== -->

<!-- SERVICE PROVIDER SECTION -->

<!-- ================================================================== -->

<ows:ServiceProvider>

<ows:ProviderName>lat/lon GmbH</ows:ProviderName>

<ows:ProviderSite xlink:href="http://www.some.com" />

<ows:ServiceContact>

<ows:IndividualName>Rutger Bezema</ows:IndividualName>

<ows:PositionName>developer</ows:PositionName>

<ows:ContactInfo>

<ows:Phone>

<ows:Voice>+49 228 184960</ows:Voice>

<ows:Facsimile>+49 228 1849629</ows:Facsimile>

</ows:Phone>

<ows:Address>

<ows:DeliveryPoint>Aennchenstr. 19</ows:DeliveryPoint>

<ows:City>Bonn</ows:City>

<ows:AdministrativeArea>Northrhine-Westfalia</ows:AdministrativeArea>

<ows:PostalCode>53177</ows:PostalCode>

<ows:Country>Germany</ows:Country>

<ows:ElectronicMailAddress>bezema@lat-lon.de_</ows:ElectronicMailAddress>

</ows:Address>

<ows:OnlineResource xlink:href="http://www.lat-lon.de" />

<ows:HoursOfService>24x7</ows:HoursOfService>

<ows:ContactInstructions>Write an email, or call</ows:ContactInstructions>

</ows:ContactInfo>

<ows:Role>PointOfContact</ows:Role>

</ows:ServiceContact>

</ows:ServiceProvider>

<!-- ================================================================== -->

<!-- OPERATIONS METADATA SECTION -->

<!-- ================================================================== -->

<ows:OperationsMetadata>

<ows:Operation name="GetCapabilities">

<ows:DCP>

<ows:HTTP>

<ows:Get xlink:href="http://localhost:8080/deegree-wpvs/services">