Pitney Bowes MapXtreme - Manual (Page 388)

Chapter 22: Web Feature Service
Web Feature Service
MapXtreme v7.1 395 Developer Guide
Web Feature Service
MapXtreme provides a Web Feature Service (WFS) implementation to send requests over the
Internet or through a private intranet to retrieve geospatial data encoded in Geography Markup
Language. While a
Web Map Service yields a map image, requests to a WFS Server will generate
GML, a form of XML that can capture geographic data.
A basic WFS client can send three kinds of requests to a WFS server. A get capabilities request
asks a server to list the geographic data it can provide and the operations that can be applied to that
data. A describe feature type request asks a server to describe the data it can provide for a
geographic feature. Finally the server can be asked to provide the actual data.
Geographic data from a WFS consists of descriptions about the data. At this point the retrieved data
is not viewable as a map layer in MapXtreme. However, using MapXtreme’s WfsClient, the GML
output can be converted into a form MapXtreme can work with: MultiFeatureCollections. These
feature collections can then be treated like any other FeatureCollection in MapXtreme whereby you
can apply themes, labels and perform a variety of analytical operations.
The MapXtreme WFS server implementation complies with the 1.0.0 OpenGIS® Web Feature
Service Implementation Specification as a WFS Basic profile. A link to this document can be found
at
www.opengis.org . MapXtreme’s WFS implementation does not support the Transaction WFS
specification at this time.
Requests for features via MapXtreme’s WFS implementation are made with HTTP GET or HTTP
POST requests. The response is returned in GML2 by default; however, a request can explicitly ask
for a response in GML3.
MapXtreme’s support for WFS consists of two parts—a WFS Server and WFS client. This chapter
explains how to configure a WFS server if you want to host your own data for others to access. See
Configuring a WFS Server .
If you are interested in accessing data from other WFS servers on the internet or from a private
intranet, see
Using the MapXtreme WFS Client Programmatically .
The following section describes the WFS Server operations available through MapXtreme WFS.
Understanding WFS Server Operations
There are three WFS Server operations that provide the basis for the MapXtreme WFS server
implementation: GetCapabilities, DescribeFeatureType, and GetFeature.
GetCapabilities
A GetCapabilities request is a query of a WFS server to learn more about what the server offers in
terms of geographic data and operations that can be performed on that data. The response to a
GetCapabilities request is an XML document describing the operations that the WFS supports and a
list of all feature types that it can service. You would request the service’s capabilities the first time
you access a WFS server.
GetCapabilities is supported via HTTP GET and HTTP POST.