Web Services - Interoperability with NZTopoOnline

NZTopoOnline has a Web Map Service (WMS) connection available. This Open Geospatial Consortium (OGC) -compliant service lets other applications connect to NZTopoOnline via the Internet.

Users can combine geographical information from different WMS-compliant sources with NZTopoOnline data and study the result in any WMS-capable application or viewer.

These applications and viewers use LINZ data in real time, directly accessing the authoritative version. As they do not replicate the dataset they don't need to maintain its currency themselves.

This is a simple example of web map interoperability. New insights can be gained by combining views of overlaid geographical features derived from disparate sets of geographical information.

Examples:

• Administrative areas are overlaid on a view of NZTopoOnline.
• A third party application is developed to integrate views of NZTopoOnline with other data for a specific online, realtime application.

WMS services available:

The WMS Service is temporarily unavailable on NZTopoOnline.

This is a software compatibility issue, which will be resolved in the next update scheduled for July 2008. The WMS service will be available following the July update.

We regret any inconvenience caused.

Last updated Friday 6 June 2008, 11.35 am.

Minimum prerequisites to use this service

You need …

• a WMS-capable application or viewer (many are available free on the Web - search for "WMS viewers")
• URL(s) for the WMS services as described above, and
• some knowledge of map data to ensure results can be relied upon, ie, which are valid data combinations and interpretations to make, and which are not

Example

Follow these instructions to demonstrate the WMS NZTopoOnline:

1. Connect to site http://www.wmsviewer.com
2. Click on Edit Servers button
3. Remove any pre-existing layers using the Remove button
4. Click Add New button
5. In 'Or Enter URL:' box type in: http://www.nztopoonline.linz.govt.nz/wmsconnector/com.esri.wms.Esrimap?ServiceName=nztopo_wms&
6. Click OK
7. Click check box next to 'Select All Layers'
8. Click OK
9. Click Update Maps
10. Use the Zoom Area tool to zoom in on a selected part of New Zealand. Layers / Features should start appearing as you zoom in.

Troubleshooting

1. Ensure you application or viewer can support either version 1.0.0, 1.1.0 or 1.1.1 of WMS
2. If you are trying to connect to the service using an application from behind a firewall, check with your System Administrator that you have appropriate access through the firewall.

What is WMS?

The Web Map Service Specification is an open international standard developed by the Open Geospatial Consortium. It describes the three functions in a WMS-compliant service:

1. how to find out what types of maps the WMS service can provide
2. how to request a map from a WMS service, and
3. how to request information about a feature at a particular location.

For more technical information visit OGC. WMS is a geospatial interoperability specification referenced as part of the New Zealand e-Government Interoperability framework.

Current limitations…

• There is no catalogue of all online WMS services and so no robust way to discover web map services with the WMS connector.
• You need to download a free viewer, ie the viewing tools are not yet integrated into the standard web browsers.
• There are low levels of information online about the data. This information is needed to help users determine the quality of results in their generated map(s). There is insufficient metadata to help quantitative and qualitative analysis of the results.
• There is no ability in the current LINZ WMS implementation of NZTopoOnline to specify style of the output (what you get is what you get).

We want to hear from you

NZTopoOnline has been made accessible via the WMS connector to enable individuals or organisations to consider the possibilities and to allow experimentation of WMS services. LINZ is interested to learn of any examples, including prototypes which use the service. Please email nztol@linz.govt.nz