Hiding/Enabling/Ignoring Layers in OGC Web Services

Introduction

Everybody recognizes the need to be able to hide layers from a given mapfile from some or all OGC Web Service (OWS) requests. Some tickets about this are as old as 6 years old. Unfortunately we have been unable to come up with a solution because there are several angles to consider in approaching the problem.

The goal of this page is to organize the resolution of this issue as follows:

1. Start by collecting use cases
2. Present and discuss possible solutions
3. Write and vote/approve a RFC
4. Implement the solution and enjoy!

References

Tickets:

• ticket:337 : Need a way to prevent layers from being served via WMS
• ticket:300 : Extend behavior of DUMP mapfile parameter for GML output
• ticket:1952 : Tileindex Layer and WMS Get Capabilities
• ticket:2582 : OWS GetCapabilities should skip layers with status == MS_DELETE

Mailing list discussions:

• This ​February 2009 mapserver-users thread started with ticket:2582 and turned into a long exchange with some interesting use cases

Use Cases

1. One needs the ability to hide tileindex layers to all OGC services

2. In a WMS mapfile where multiple scale-dependent layers are in a common group, we want only the group to appear in GetCapabilities and not the individual layers. However the layers should not be completely turned off since we want them to be visible in GetMap and queryable with GetFeatureInfo when the group is selected. This use case is common for WMS and may (or may not) apply to other OGC services.

3. One may want to offer a given layer via WMS but not via WFS (or any combination of services). In other words, we need the ability to select in which OGC services a given layer is exposed.

4. The copyright notice shall not appear in the GetCapabilities output and shall not be queryable.

5. ...

Proposed Solutions

Solution 1

Disable each request type per service. The metadata section of the layer object could be extended by a key [service]_disable_request. Each request type listet in this key will not be processed for the given service. The value all will disable a service completely. Examples:

    wfs_disable_request 'all'
    wms_disable_request 'getcapabilities getfeatureinfo'

The docs must contain clear warnings about the behaviour of the feature, esp. the value 'all', the 'ows' string for [service] and OGC compability.

Solution 2

Enable or disable a service by a new map file setting SERVICE WMS|WFS. The DUMP TRUE setting could be used to control GetFeatureInfo requests. In order to hide a layer a new metadata [service]_hidden_layer could be used.

Solution 3

...

Conclusion / Final Solution

The final solution will be the object of a RFC... link to this RFC here when we get there.