Web Feature Services, Considerations for CGDI Government Partners

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Web Feature Services, Considerations for CGDI
Government Partners
June 2006
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Discussion

• Purpose of Report
• What is WFS (high-level)
• Case Studies
• WFS Implications
• Business
• Technical
• Recommendations

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Purpose of Report

• Review the WFS Standard (OGC/CGDI)
• Review how WFS has been implemented by government
  organizations
• Review the business and technical implications in
  engaging WFS and
• Provide recommendations with respect to use of
  WFS within CGDI context.

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Main Areas of Consideration

• WFS digital rights and business process support
• WFS Security and performance
• WFS used for data dissemination between
  Municipal, Provincial and Federal partners and
• WFS as a potential aggregation service fusing
  disparate feature and attribute information.

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What is WFS

• An Open Geospatial Consortium (OGC) standard for
  exchange of geographic features and associated
  attributes between computer systems.
• A WFS interface when requested will return an
  exchange file format called Geography Markup
  Language (GML)

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• WFS contains attributes and therefore can contain
  more information than other OGC services.
• It is the amount of information communicated that
  makes WFS valuable to users but requires more
  time to process the data.

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GML

• Geography Markup Language is the data feed
  portion of WFS and is the most important
  component of the process.
• GML standards and schemas changed regularly from
  2000-2004.
• Most recently GMLsf has implemented a simple
  feature schema that is intended to provide data
  providers and application developers the
  stability to use WFS.

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Case Studies

• GeoConnections Discovery Portal has 21 WFSs
  registered, all WFS 1.0.0
• Reviewed government organizations currently using
  WFS
• Statistics Canada
• GeoNova
• Natural Resources Canada Centre for Topographic
  Information, Sherbrooke.
• Natural Resources Canada Geobase Portal

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Case Studies - Comments

• WFS is used as in intranet service
• GML files are served to the public
• Different vendor products currently do not
  produce fully compatible GML
• Client applications for WFS are rare
• Digital rights management is a concern
• GeoNames is an excellent example of a WFS
  implementation and
• Need a coordinated architecture to understand how
  WFS is to be used by organizations at different
  points along the supply chain.

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WFS Implications

• Technical Implications
• Standards Adoption
• Performance
• Distributed Data and Services
• Separation of geometry and attributes
• Redundancy
• End User Access

• Business Implications
• Service Level Commitments
• Service Security
• Digital Rights

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Architecture
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Recommendations

• WFS should be implemented by organizations that
  maintain vector data
• WFS services should initially be used for data
  processing and as access interfaces and not as
  client application interfaces
• Investigate the detailed impacts of a new
  services security architecture based on the
  peer-to-peer model and certificate authorization
• Implement a WFS cascading cache capability to
  address redundancy, performance and service level
  commitments and
• Implement digital rights text within the WFS
  response GML.

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Next Steps

• Detailed Operational Architecture
• Define the operational architecture for key data
  sources within CGDI, allowing organizations to
  understand where in the processes they should
  participate.
• Establish CGDI test beds for WFS
• Key to address operational issues and not just
  prove technology.
• Guidelines for WFS
• Assist technology managers to understand which
  best practices are to be applied to ensure
  effective implementation of WFS.

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Web Feature Services, Considerations for CGDI
Government Partners

• This report and presentation was made possible by
  the Natural Resources Canada, Earth Sciences
  Sector, Geomatics for Connecting Canadians
  Program.
• This report and presentation was prepared by the
  team at
• chris.dejager_at_amec.com