MapGuide RFC 39 - Add layer name to WMS GetFeatureInfo response

This page contains a change request (RFC) for the MapGuide Open Source project. More MapGuide RFCs can be found on the RFCs page.

Status

RFC Template Version	(1.0)
Submission Date	Oct 7, 2007
Last Modified	Chris Claydon Timestamp
Author	Chris Claydon
RFC Status	draft
Implementation Status	Not implemented
Proposed Milestone	2.0
Assigned PSC guide(s)	(when determined)
Voting History	Oct 7, 2007

Overview

The WMS GetFeatureInfo request is capable of returning information for multiple features. However, it is not possible to determine which features are from which layer(s). A Trac ticket (#225) was created for this problem. This RFC contains a proposal that will allow us to return the layer name of the layer containing each of the queried features.

Motivation

Applications that make use of MapGuide's WMS support can use the GetFeatureInfo request type to return information about features clicked on by the user. However, it is not possible to determine which layer the features come from, and this restricts the usefulness of this method.

Proposed Solution

The proposed solution is to add an extra property to the set of feature properties returned by the Rendering Service's QueryFeatureProperties method. The property name will be "_MgLayerName" (which is unlikely to conflict with "real" feature property names), and the value will be the name of the layer that contains the feature.

The web tier implementation of the WMS service will extract the layer name from this property and insert it into the WMS response.

Implications

The response from the WMS GetFeatureInfo request will now contain the layer name for each returned feature.

Test Plan

The web tier test pages can be used to issue sample requests, and verify that the layer names are included in the response.

Funding/Resources

Supplied by Autodesk.