[mapserver-users] [mapserver-dev] FW: WMS request fails when spaces are encoded as plus symbol in query part of URL

Rahkonen Jukka (Tike) jukka.rahkonen at mmmtike.fi
Thu Aug 21 06:27:53 PDT 2014


Hi,

A little bit more information. Here is a GetMap request that returns an image from ArcGIS server. Space is changed into "%20" and letter "ä" is changed into "%C3%A4" . This, according to http://www.albionresearch.com/misc/urlencode.php, seems to implement RFC3986.

http://gtkdata.gtk.fi/arcgis/services/GTKWMS/MapServer/WMSServer?REQUEST=GetMap&SERVICE=WMS&VERSION=1.1.1&WIDTH=459&HEIGHT=346&LAYERS=Suomen%20maaper%C3%A4kartta%201:1%20000%20000&TRANSPARENT=TRUE&FORMAT=image%2Fpng&BBOX=434844.4854575534,7035986.957235612,452739.30027509434,7144417.839725949&SRS=EPSG:3067&STYLES=

The mode where space is encoded as "+" seems to be something that is called "RFC2396 mode". In this mode letter "ä" will become "%E4". The following test where I have only changed "%C3%A4"  into "%E4" proves that ArcGIS server does not support RFC2396 mode.

http://gtkdata.gtk.fi/arcgis/services/GTKWMS/MapServer/WMSServer?REQUEST=GetMap&SERVICE=WMS&VERSION=1.1.1&WIDTH=459&HEIGHT=346&LAYERS=Suomen%20maaper%E4kartta%201:1%20000%20000&TRANSPARENT=TRUE&FORMAT=image%2Fpng&BBOX=434844.4854575534,7035986.957235612,452739.30027509434,7144417.839725949&SRS=EPSG:3067&STYLES=

If http://www.ietf.org/rfc/rfc3986.txt is newer than http://www.ietf.org/rfc/rfc2396.txt I can imagine that there are servers which support either the old, or the new, or both, or neither. Should ther be a RFC2396/RFC3986 switch for selecting the URL-encoding method to use? Or is RFC2396 deprecated and ESRI is doing the right thing by supporting only RFC3986 and Mapserver should do the same?


-Jukka Rahkonen-


Rahkonen Jukka wrote:
> 
> Hi,
> 
> Here is an ArcGIS WMS to  test with.
> http://gtkdata.gtk.fi/arcgis/services/GTKWMS/GTKWMS/MapServer/WMSServe
> r?request=GetCapabilities&service=WMS
> 
> Do it quickly because I have asked the service provider to change the layer
> names, and guess what - because I could not make our Mapserver to cascade
> the service. You will find layer names like <Name>Maaperä 1:20 000; 1:50
> 000</Name>
> 
> I would really much like to know also how the non-ascii characters should be
> handled in the mapfile when cascading such layers.
> 
> -Jukka Rahkonen-
> 
> 
> 
> Jeff McKenna wrote:
> 
> > spaces are encoded as plus symbol in query part of URL
> >
> > I agree it's a change that should slip in now for 7.0, but I hope
> > those with later ArcServer versions can test it in the beta (or we
> > have one volunteer to let us use their Arc WMS instance for testing).
> >
> > -jeff
> >
> >
> >
> > On 2014-08-20 1:52 PM, Lime, Steve D (MNIT) wrote:
> > > Devs: Is this a change that we should make for 7.0? Seems reasonable
> > > but I'm not sure what the side effects might be.
> > >
> > > Steve
> > >
> > > *From:*Moen, Paul T. [mailto:pmoen at nd.gov]
> > > *Sent:* Wednesday, August 20, 2014 9:44 AM
> > > *To:* Lime, Steve D (MNIT); mapserver-users at lists.osgeo.org
> > > *Subject:* Re: [mapserver-users] WMS request fails when spaces are
> > > encoded as plus symbol in query part of URL
> > >
> > > Steve,
> > >
> > > You are right about the outcome of 1 and 2.  1 encodes the % and 2
> > > throws the following error.
> > >
> > > msBuildWMSLayerURLBase(): One of wms_onlineresource,
> > > wms_server_version, wms_name metadata is missing in layer USGS DRG
> > > 250k Topo Maps.  Please either provide a valid CONNECTION URL, or
> > > provide those values in the layer's metadata.\n\n
> > >
> > > I found the function as you said and
> > >
> > > I removed the
> > >
> > >   if (*i == ' ')
> > >
> > >        *j = '+';
> > >
> > >      else
> > >
> > > from the function then recompiled.
> > >
> > >     char *msEncodeUrlExcept(const char *data, const char except)
> > >
> > >     {
> > >
> > >        char *hex = "0123456789ABCDEF";
> > >
> > >        const char *i;
> > >
> > >        char  *j, *code;
> > >
> > >        int   inc;
> > >
> > >        unsigned char ch;
> > >
> > >        for (inc=0, i=data; *i!='\0'; i++)
> > >
> > >          if (msEncodeChar(*i))
> > >
> > >            inc += 2;
> > >
> > >        code = (char*)msSmallMalloc(strlen(data)+inc+1);
> > >
> > >        for (j=code, i=data; *i!='\0'; i++, j++) {
> > >
> > >          if ( except != '\0' && *i == except ) {
> > >
> > >            *j = except;
> > >
> > >          } else if (msEncodeChar(*i)) {
> > >
> > >            ch = *i;
> > >
> > >            *j++ = '%';
> > >
> > >            *j++ = hex[ch/16];
> > >
> > >            *j   = hex[ch%16];
> > >
> > >          } else
> > >
> > >            *j = *i;
> > >
> > >        }
> > >
> > >        *j = '\0';
> > >
> > >        return code;
> > >
> > >     }
> > >
> > > Everything works again after a mapserver recompile, install and
> > > finally a restart of apache.  Thanks so much for the path to the solution.
> > >
> > > Paul Moen
> > > pmoen at nd.gov <mailto:pmoen at nd.gov>
> > > 701-328-2434
> > >
> > > *From: *<Lime>, "Steve D (MNIT)" <Steve.Lime at state.mn.us
> > > <mailto:Steve.Lime at state.mn.us>>
> > > *Date: *Wednesday, August 20, 2014 at 12:41 AM
> > > *To: *Paul Moen <pmoen at nd.gov <mailto:pmoen at nd.gov>>,
> > > "mapserver-users at lists.osgeo.org
> > > <mailto:mapserver-users at lists.osgeo.org>"
> > > <mapserver-users at lists.osgeo.org
> > > <mailto:mapserver-users at lists.osgeo.org>>
> > > *Subject: *RE: [mapserver-users] WMS request fails when spaces are
> > > encoded as plus symbol in query part of URL
> > >
> > > Hmmm... Nice backwards compatibility ESRI. The +'s seem to still be
> > > quite legal (http://tools.ietf.org/html/rfc3986 and other
> > > references) in the query string (but not the path). I don't have
> > > access to test and I'm guessing these ideas won't work but they might be
> worth a quick try:
> > >
> > >    1) Try encoding the wms_name in the metadata: "wms_name"
> > > "Topomap%20DRG%20250k"
> > >
> > >    2) Don't set the wms_name in the metadata but add it to the
> > > connection: CONNECTION
> > >
> > "http://ndgishub.nd.gov/arcgis/services/All_Elevation/MapServer/WMSSer
> > ver?L
> > AYERS=Topomap%20DRG%20250k&"
> > >
> > > I'm betting MapServer will encode the %'s in 1 and throw an error in 2.
> > > Otherwise you could hack the MapServer source. Function is called
> > > msEncodeUrlExcept() in mapstring.c you can see the section to change
> > > starting at line 1138 in git master
> > > (https://github.com/mapserver/mapserver/blob/master/mapstring.c)
> > > <https://github.com/mapserver/mapserver/blob/master/mapstring.c).>
> > >
> > > Maybe it's worth making this change as part of 7.0?
> > >
> > > Steve
> > >
> > > --------------------------------------------------------------------
> > > --
> > > --
> > >
> > > *From:*mapserver-users-bounces at lists.osgeo.org
> > > <mailto:mapserver-users-bounces at lists.osgeo.org>
> > > [mapserver-users-bounces at lists.osgeo.org
> > > <mailto:mapserver-users-bounces at lists.osgeo.org>] on behalf of Moen,
> > > Paul T. [pmoen at nd.gov <mailto:pmoen at nd.gov>]
> > > *Sent:* Tuesday, August 19, 2014 4:56 PM
> > > *To:* mapserver-users at lists.osgeo.org
> > > <mailto:mapserver-users at lists.osgeo.org>
> > > *Subject:* [mapserver-users] WMS request fails when spaces are
> > > encoded as plus symbol in query part of URL
> > >
> > > Hi all,
> > >
> > > We are consuming WMS services hosted by ESRI ArcGIS Server 10.0.
> > > The server was upgraded to ArcGIS Server 10.2.2 and we no longer can
> > > access layer names with spaces.
> > >
> > > This is the server's capabilities.
> > >
> > > http://ndgishub.nd.gov/arcgis/services/All_Elevation/MapServer/WMSSe
> > > rv er?request=GetCapabilities&service=WMS
> > >
> > > This is the layer I am using.
> > >
> > > LAYER
> > >
> > > # DEBUG 5
> > >
> > > CONNECTIONTYPE WMS
> > >
> > > CONNECTION
> > >
> >
> "http://ndgishub.nd.gov/arcgis/services/All_Elevation/MapServer/WMSServer?"
> > >
> > > METADATA
> > >
> > > "wms_name" "Topomap DRG 250k"
> > >
> > > "wms_format" "image/png"
> > >
> > > "wms_server_version" "1.1.1"
> > >
> > > "wms_srs" "EPSG:2266"
> > >
> > > END
> > >
> > > TYPE RASTER
> > >
> > > STATUS OFF
> > >
> > > NAME "USGS DRG 250k Topo Maps"
> > >
> > > END
> > >
> > > Mapserver encodes this request as follows.  Notice that the layer
> > > name, which is 'Topomap DRG 250k', is encoded with the spaces
> > > becoming the
> > '+'
> > > character.
> > >
> > > http://ndgishub.nd.gov/arcgis/services/All_Elevation/MapServer/WMSSe
> > > rv
> > >
> >
> er?LAYERS=Topomap+DRG+250k&REQUEST=map&WMTVER=1.0.0&SERVICE=W
> > MS&FORMAT
> > >
> >
> =image/png&STYLES=&HEIGHT=1146&SRS=EPSG:2266&WIDTH=1271&BBOX=19
> > 06240.1
> > >
> >
> 5992838,596656.333359479,2119730.85012732,789150.692893686&TRANSPAR
> > ENT
> > > =TRUE&EXCEPTIONS=INIMAGE
> > >
> > > This returns the error in an image that says "Parameter 'layers'
> > > contains unacceptable layer names."
> > >
> > > When I replace the + in the layer name with %20,
> > > LAYERS=Topomap+DRG+250k become LAYERS=Topomap%20DRG%20250k
> > and the request becomes the following.
> > >
> > > http://ndgishub.nd.gov/arcgis/services/All_Elevation/MapServer/WMSSe
> > > rv
> > >
> >
> er?LAYERS=Topomap%20DRG%20250k&REQUEST=map&WMTVER=1.0.0&SERVI
> > CE=WMS&FO
> > >
> >
> RMAT=image/png&STYLES=&HEIGHT=1146&SRS=EPSG:2266&WIDTH=1271&BB
> > OX=19062
> > >
> >
> 40.15992838,596656.333359479,2119730.85012732,789150.692893686&TRAN
> > SPA
> > > RENT=TRUE&EXCEPTIONS=INIMAGE
> > >
> > > That request works.  Obviously, ESRI is no longer decoding + as a
> > > space and therefore does not recognize the layer name with spaces.
> > >
> > > Is there any way I can have mapserver encode all characters using
> > > percent-encoding, or at least encode spaces as %20 instead of a + character.
> > >
> > > Thanks,
> > >
> > > Paul Moen
> > > pmoen at nd.gov <mailto:pmoen at nd.gov>
> > > 701-328-2434
> > >
> > >
> > _______________________________________________
> > mapserver-dev mailing list
> > mapserver-dev at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/mapserver-dev


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