OGC Web Feature Service (WFS)

Web Feature Service (WFS)

1) Overview

The WFS specification defines interfaces for describing data manipulation operations of geographic features. Data manipulation operations include the ability to:

• get or query features based on spatial and non-spatial constraints

• create a new feature instance

• delete a feature instance

• update a feature instance

The basic Web Feature Service allows querying and retrieval of features. A transactional Web Feature Service (WFS-T) allows creation, deletion, and updating of features.

A WFS describes discovery, query, or data transformation operations. The client generates the request and posts it to a web feature server using HTTP. The web feature server then executes the request. The WFS specification uses HTTP as the distributed computing platform, although this is not a hard requirement.

The are two encodings defined for WFS operations:

• XML (amenable to HTTP POST/SOAP)
• Keyword-Value paris (amenable to HTTP GET/Remote procedure call)

In the taxonomy of Web Services, WFS is best categorized as a non-RESTful RPC type service.

from wikipedia.org

2) Download

Document
2.0	OpenGIS Web Feature Service 2.0 Interface Standard (also ISO 19142)
1.1.0	OpenGIS Web Feature Service (WFS) Implementation Specification
1.0.0	Web Feature Service

Schemas
2.0	wfs.xsd
1.1.0	wfs.xsd
1.0.0	OGC-exception.xsd  WFS-basic.xsd  WFS-capabilities.xsd  WFS-transaction.xsd  wfs.xsd

3) Operations

All version of WFS support the these operations:

Operation	Description
GetCapabilities	Generates a metadata document describing a WFS service provided by server as well as valid WFS operations and parameters
DescribeFeatureType	Returns a description of feature types supported by a WFS service
GetFeature	Returns a selection of features from a data source including geometry and attribute values
LockFeature	Prevents a feature from being edited through a persistent feature lock
Transaction	Edits existing feature types by creating, updating, and deleting

The following operations are available in version 1.1.0 only:

Operation	Description
GetGMLObject	Retrieves features and elements by ID from a WFS

The following operations are available in version 2.0.0 only:

Operation	Description
GetPropertyValue	Retrieves the value of a feature property or part of the value of a complex feature property from the data store for a set of features identified using a query expression
GetFeatureWithLock	Returns a selection of features and also applies a lock on those features
CreateStoredQuery	Create a stored query on the WFS server
DropStoredQuery	Deletes a stored query from the WFS server
ListStoredQueries	Returns a list of the stored queries on a WFS server
DescribeStoredQueries	Returns a metadata document describing the stored queries on a WFS server

Operation Request Encoding

4) Reference

• http://www.opengeospatial.org/standards/wfs

• http://schemas.opengis.net/wfs/

• http://mapserver.org/ogc/wfs_server.html

• http://docs.geoserver.org/stable/en/user/services/wfs/reference.html