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Welcome

This section will provide a context to the use of web feature services (WFS). It covers who and what the OGC is and does, what a WFS is, and the history behind OGC WFS specifications.

Open Geospatial Consortium (OGC) and their goal... 

"The Open Geospatial Consortium is an international industry consortium of 440* companies, government agencies and universities participating in a consensus process to develop publicly available interface standards."              *(to date).

"The OGC Standards support interoperable solutions that "geo-enable" the Web, wireless and location-based services and mainstream IT."

In a nutshell then, the OCG is a group of people from industry, government and education who together, produce standards for use in a global context, their ultimate goal being to better enable the use of geospatial solutions. You can read more on the OGC from the Further Reading section below.

What is an OGC Web Feature Service?

In order to understand what a WFS is, you first must understand what is meant by:

  • 'Feature'
  • 'Operation'

In the context of a WFS, a 'Feature' is a representation of a real-world-object; a geographic feature. That feature is represented by 'data' and is often contained in a database.

An 'Operation' can be thought of as an action - something that performs an action on a data store that itself contains features. Operations are used for retrieving and maintaining that data. The type of action (or Operator to use) depends on end user requirements. The different types of Operations available for use within a WFS are detailed in WFS Operation Types and Descriptions.

Therefore a Web Feature Service is...

An open, platform independent web service (request/response) allowing retrieval and maintenance of features contained within a remote data store. The WFS provides a set of comprehensive operations for discovery, query and transactions on features or individual property values.

What is an Application Server?

An application server is a server often used solely to host applications (software programs). The two application servers we work with are Tomcat (Wikipedia) and JBoss (Wikipedia).

What is the WFS process?

Client applications link to the WFS hosted by the application server (e.g Tomcat or JBoss) and submits a WFS request. WFS converts the request to SQL (or other depending on the database in use) to query the underlying database. Data is returned and the WFS then converts it into gml, based on the GO Publisher project translations and specified schema. The client application then displays the gml data.

Image displaying the WFS setup using an application server.

What can WFS be used for?

WFS supports a wide range of use cases:

Data exchange: download data on request or synchronisation for use locally.

Decision-support: directly query data within client applications removing the need for local data stores.

Data maintenance: direct, distributed data maintenance by multiple clients. Removing the need for multiple data maintenance flows, increasing efficiency and quality and reducing latency. 

History of OGC WFS Specification

The WFS specification is one of the more mature web service standards developed by the OGC. See WFS Conformance Classes for more information on

WFS 1.0.0

The WFS specification was first developed in 2002 (WFS 1.0.0) alongside the GML 2.1.2 specification which is the default payload encoding.

The first version of the WFS specification supported 5 operations:

  1. GetCapabilities,
  2. DescribeFeatureType,
  3. GetFeature,
  4. Transaction and
  5. LockFeature.

WFS 1.1.0

The specification was subsequently revised in 2005, following the development of the GML 3.1.1 and Filter Encoding 1.1 specifications.

The WFS 1.1.0 specification included 2 new operations;

  • GetGMLObject and
  • GetFeatureWithLock

It also introduced some new query functions such as resolving references to remote features/objects. WFS 1.1.0 was the first version of the specification to be implemented by many proprietary and open source software vendors and you can now find several compliant WFS 1.1 servers.

WFS 2.0

In November 2010, the latest version of the WFS specification (WFS 2.0) was published. This was a major release of the WFS specification as it has now been adopted as an ISO TC 211 standard as well as an OGC specification, demonstrating maturity. The WFS 2.0 specification is currently being adopted by many national, international and global initiatives within many domains (e.g. INSPIRE, NSDI, SESAR/NextGen) as the preferred open web service interface for interoperable data exchange.

In the WFS 2.0 specification, four core WFS Conformance Classes are defined that specify a minimum set of operations and behaviours that the WFS supports.

Overview of key differences between the WFS specifications

GO Publisher WFS

Snowflake Software's GO Publisher has been extended to support both WFS1.1 and the latest version of the OGC Web Feature Service (WFS 2.0) and Filter Encoding Specification (FES) 2.0. These are the sibling standards to GML3.2.1 and introduce new ways to interact with spatial and temporal data. This is key functionality for fully implementing a number of important GML exchange schemas.

Notable schemas which use GML3.2.1, WFS 2.0 & FES 2.0:

  •     AIXM5.1 - Aeronautical Information Exchange Model
  •     WXXM1.1 - Weather Exchange Model
  •     INSPIRE - Infrastructure for Spatial Information in Europe to support environmental policies
  •     CAFE - Clean Air For Europe initiative

Make your WFS RESTful!

Introducing REST Services provides you with an introduction to implementing your WFS using Representational state transfer (REST) infrastructure.

Further Reading

You can either read GO Publisher WFS User Guide or GO Publisher WFS Administrator Guide. To find out which would suit you best, return to the GO Publisher WFS 4.2 homepage.

Open Geospatial Consortium (Wikipedia)

About the Open Geospatial Consortium

Web Feature Service (Wikipedia)