GetFeatureInfo GML response format parser

[mpriour]

GetFeatureInfo responses in GML format from a number of map server / feature server applications can not be directly parsed using the current OpenLayers.Format.GML implementation, nor any of its subclasses.

The challenge, however, is that the GML GetFeatureInfo response format has no OGC schema nor any implementation guidelines from that organization. In fact, it is an optional response format. Due to the lack of standards, GML GetFeatureInfo responses can be highly variable. Therefore either a broadly generic approach to parsing is needed or numerous "flavors" of GML GetFeatureInfo format readers would need to be created.

[mpriour]

Patch containing contents of GML_GFI.js

[mpriour]

GML GetFeatureInfo Format reader

[mpriour]

I have attached my first attempt at writing a GML GetFeatureInfo response format parser. This is targeted at the default GML GetFetureInfo response from Mapserver 5. It MAY work with other WMS implementations, but has not been tested.
The attached OpenLayers.Format.GML_GFI class works well for the specific purpose and application it was developed for, but likely requires significant work and testing to be more broadly applicable and be up to full OpenLayers coding standards.

[bartvde]

Hi Matt, your code currently fails against an empty Mapserver output, e.g.:

<msGMLOutput 
	 xmlns:gml="http://www.opengis.net/gml"
	 xmlns:xlink="http://www.w3.org/1999/xlink"
	 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
</msGMLOutput>

I had to change the following for that:

            while (child && child.nodeType != 1) {
                child = child.nextSibling;
            }
            tagName = (child ? child.nodeName : '');

[bartvde]

I've been working a bit on this as well in my bartvde/wmsgetfeatureinfo sandbox, and added some tests. I've verified my Format works for ESRI, Ionic, Geoserver and Mapserver. I chose an approach whereby there are 2 specific Format classes, one for the msGMLOutput from Mapserver, and one of ESRI's FeatureInfoResponse (both ArcIMS and ArcGIS Server use this). The parser falls back on Format.GML which works fine for Ionic and Geoserver. I'll attach a patch.

[bartvde]

patch from sandbox/bartvde/wmsgetfeatureinfo

[ahocevar]

Thanks Bart for this contribution. Only one minor change that I made: I renamed the layerName property that the msGMLOutput parser adds to the feature to type. The reason is that we are planning to add this property to the feature anyway for multiple typename support (see #1838 and #1961).

[ahocevar]

Bart: one more change that I made: I put all readers into one class, because determining the reader from a node name is more like our readers concept than the versioned parsers concept.

[tschaub]

parse GetFeatureInfo responses

[tschaub]

Thanks for the work on this. I think it looks good to go. The updated patch only contains minor tweaks (copyright, read_msGMLOutput always returns array, some ndoc, some array length caching).

[ahocevar]

(In [8920]) WMSGetFeatureInfo class with tests. Should have gone in with my previous commit, but forgot to svn a. (see #1812)

[ahocevar]

closed as of #8919 and #8920

[ahocevar]

closed as of r8919 and r8920 (not my day today as it seems)

[tschaub]

(In [8925]) Correcting what was the result of a patch applied twice - thanks for the catch elemoine. r8920 added the WMSGetFeatureInfo format with the class definition repeated (and slightly different). (see #1812)