ArcMap cannot access WCS version 2.0.1 on MapServer?

Question

I have a MapServer 7.0.7 map containing only a layer with a GeoTiff DEM.

It works perfectly with QGIS 3.0.3 but I cannot use it with ArcMap 10.5.

This is my map file:

MAP
  OUTPUTFORMAT
      NAME "GTiff"
      DRIVER GDAL/GTiff
      MIMETYPE "image/tiff"
      IMAGEMODE FLOAT32
      EXTENSION "tif"
    TRANSPARENT ON
  END

  NAME "Modèle numérique de terrain"
    EXTENT  -6.0001389 39.9998611 10.0001389 52.0001389
    MAXSIZE 4096
    PROJECTION
        "init=epsg:2154"
  END

  WEB
    METADATA
            "wcs_label"           "WCS Server"
            "wcs_onlineresource"  "http://localhost/cgi-bin/mapserv?map=/tmp/testNaN.map&"
            "wcs_enable_request" "*"
            "wcs_fees"            "none"
            "wcs_accessconstraints"    "none"
            "wcs_keywordlist"          "wcs,dem"
            "wcs_metadatalink_type"    "TC211"
            "wcs_metadatalink_format"  "text/plain"
            "wcs_metadatalink_href"    "http://localhost"
            "wcs_address"              ""
            "wcs_city"                 "Paris"
            "wcs_stateorprovince"      "IDF"
            "wcs_postcode"             "75000"
            "wcs_country"              "France"
            "wcs_contactelectronicmailaddress" "[email protected]"
            "wcs_contactperson"            "me"
            "wcs_contactorganization"      "unemployed"
            "wcs_contactposition"          "manager"
            "wcs_contactvoicetelephone"    ""
            "wcs_contactfacimiletelephone" ""
      END
    END

  LAYER
        NAME TESTNAN
          DATA "/tmp/tmp.tif"
        STATUS ON
        TYPE RASTER
        PROCESSING "SCALE=AUTO"
        PROJECTION
           "init=epsg:2154"
        END
    METADATA
      "Altitude_band_description" "Altitude en mètres"
      "wcs_band_names" "Altitude"
      "wcs_bandcount" "1"
      "wcs_description" "Modèle numérique de terrain"
      "wcs_enable_request" "*"
      "wcs_label" "IGN BDAlti V2 (rés: 75m)"
      "wcs_name" "BDALTI75"
      "wcs_rangeset_label" "IGN BDAlti V2 (rés: 75m)"
      "wcs_rangeset_name" "BDALTI75"
      "wcs_rangeset_nullvalue" "-99999"
      "wcs_srs" "EPSG:2154"
    END
  END
END

While I add my WCS server under ArcMap 10.5 without forcing the version. ArcMap makes two HTTP GET request

:/1 - - [14/Jun/2018:16:56:14 +0200] "GET /cgi-bin/mapserv?map=/tmp/testNaN.map&SERVICE=WCS&SERVICE=WCS&REQUEST=GetCapabilities HTTP/1.1" 200 6816
::1 - - [14/Jun/2018:16:56:14 +0200] "GET /cgi-bin/mapserv?map=/tmp/testNaN.map&SERVICE=WCS&SERVICE=WCS&VERSION=2.0.1&REQUEST=DescribeCoverage HTTP/1.1" 400 536

As you can see the second request does not work and Mapserver answer a HTTP 400 error.

While entering this request in Chrome I can have the full error:

msWCSDescribeCoverage20(): WCS server error. Missing COVERAGEID parameter.

the only workaround I found is to force the version to 1.0.0

How do I make MapServer understand ArcMap WCS 2.0.1 protocol?

Answer 1

Your question should be how to make ESRI to fix their bug.

Table 11 — WCS DescribeCoverage components in the WCS 2.0.1 core standard states that coverageId is a mandatory parameter in DescribeCoverage request and the value must be one or more coverage names.

If you have only one coverage in your service a workaroud could be to add a rewrite rule to the Apache server to add &coverageId=your_coverage into the non-standard request that ArcMaps makes.

I wonder if ArcMap behaves always like that or if there is something special in your MapServer configuration. GeoServer requires coverageId as well as you can test with

https://demo.geo-solutions.it/geoserver/wcs?service=WCS&version=2.0.1&request=DescribeCoverage&

Could you test if ArcMap can add coverages from that service?

BTW. Why do you have SCALE=AUTO in your mapfile? I am not sure if it has an effect on WCS service, but if it does then it alters your data which is not the purpose of WCS.