MS RFC 75: INSPIRE view service support

Date:2011/07/01
Author:Stefan Leopold (stefan.leopold at reflex.at)
Author:Stephan Meissl (stephan.meissl at eox.at)
Last Edited:2012/03/09
Status:Adopted on 2012/03/08
Version:MapServer 6.2

1. Overview

In order to achieve INSPIRE view service compliance, several enhancements need to be implemented in MapServer to support the specification :

  • Activation of INSPIRE support (two scenarios)
  • Multi-language support for certain capabilities fields
  • Provision of INSPIRE specific metadata
  • Named group layers
  • Style section for root layer and possibly existing group layers

This RFC aggregates and extends the already provided ideas/solutions regarding INSPIRE view service support.

2. Activation of INSPIRE support

INSPIRE specific metadata can either be referenced in an external INSPIRE service metadata document (scenario 1) or can be directly embedded in the capabilities document (scenario 2). MapServer needs to support both scenarios.

As suggested in Ticket 3608, activation of the corresponding scenario for INSPIRE support takes place in the WEB.METADATA section of the mapfile through „wms_inspire_capabilities“. If activated, the corresponding INSPIRE namespace as well as appropriate validation warnings are generated in the capabilities document.

Scenario 1 - activate INSPIRE support using a reference to external service metadata

WEB
 METADATA
  "wms_inspire_capabilities" "url"
  ...
 END
END

Scenario 2 - activate INSPIRE support using embedded service metadata

WEB
 METADATA
  "wms_inspire_capabilities" "embed"
  ...
 END
END

3. Multi-language support for certain capabilities fields

INSPIRE requires multi-language support and requests a list of all supported languages as well as the default language in the capabilities document. Based on the language parameter in the GetCapabilities request, certain specific metadata values, namely

  • „wms_title“
  • „wms_abstract“
  • „wms_rootlayer_title“
  • „wms_rootlayer_abstract“
  • „wms_group_title“
  • „wms_group_abstract“
  • „wms_style_title“
  • „wms_style_<name>_title“
as well as language dependent reference data like
  • DATA „road_eng“
  • CONNECTION „db_ger“

need to be provided in the requested language. If the language is not supported (or no language parameter is present), the default language has to be used.

As suggested in Ticket 3608, all supported languages are specified as comma separated list (first language is default) through „wms_languages“ in the WEB.METADATA section of the mapfile. This language parameter is also added to the onlineresource in the GetCapabilities output.

WEB
 METADATA
  ...
  "wms_languages" "eng,ger"       #first default, values according ISO 639-2/B
  ...
 END
END

To address the second issue, different options regarding implementation were evaluated.

For language specific metadata values, a key extension method is applied.

WEB
 METADATA
  ...
  "wms_title.eng" "myservicetitle"
  "wms_title.ger" "myservicetitleger"
  "wms_abstract" "mylayerabstract"        #fallback
  "wms_abstract.ger" "mylayerabstractger"
  ...
 END
END

For language dependent reference data, a similar approach like the runtime-substitution feature of MapServer has been followed (only DATA and CONNECTION values with %language% are substituted).

...
       LAYER
        NAME TN.RoadTransportNetwork.RoadLink
        DATA "road_%language%"
        ...
       END
...

If the language is not supported (or no language parameter is present), the default language is substituted.

4. Provision of INSPIRE specific metadata

Depending on the scenario, additional metadata information is required to support the specification. The INSPIRE related fields are provided below:

Scenario 1 - INSPIRE related fields using referenced external service metadata

WEB
 METADATA
  "wms_inspire_capabilities" "url"
  "wms_languages" "eng,ger"               #first default, values according ISO 639-2/B
  "wms_inspire_metadataurl_href" "http://INSPIRE.service/metadata"
  "wms_inspire_metadataurl_format" "application/vnd.ogc.csw.capabilities.response_xml"
  "wms_keywordlist_ISO_items" "infoMapAccessService" #value according "classification of spatial data services"
  "wms_keywordlist_vocabulary" "ISO"
  "wms_title" "myservicetitle"
  "wms_abstract" "myabstract"
  "wms_fees" "conditions unknown"         #value either "no conditions apply"|default "conditions unknown"|<specific conditions>
  "wms_accessconstraints" "None"          #value according ISO 19115 (MD_RestrictionCode codelist) or default "None"
  "wms_contactorganization" "MapServer"   #responsible organization
  "wms_contactposition" "owner"           #responsible organization, value according "INSPIRE Metadata Regulation" (part D6)
  ...
 END
END

Scenario 2 - INSPIRE related fields using embedded service metadata

WEB
 METADATA
  "wms_inspire_capabilities" "embed"
  "wms_languages" "eng,ger"               #first default, values according ISO 639-2/B
  "wms_inspire_temporal_reference" "2011-09-19" #date of last revision, value according YYYY-MM-DD
  "wms_inspire_mpoc_name" "mympocname"    #point of contact
  "wms_inspire_mpoc_email" "mympoc@e.mail" #point of contact
  "wms_inspire_metadatadate" "2011-09-19" #value according YYYY-MM-DD
  "wms_inspire_resourcelocator" "http://myinspireresource" #URL for ResourceLocator
  "wms_inspire_keyword" "infoMapAccessService" #value according "classification of spatial data services"
  "wms_keywordlist_ISO_items" "infoMapAccessService"
  "wms_keywordlist_vocabulary" "ISO"
  "wms_title" "myservicetitle"
  "wms_abstract" "myabstract"
  "wms_fees" "conditions unknown"         #value either "no conditions apply"|default "conditions unknown"|<specific conditions>
  "wms_accessconstraints" "None"          #value according ISO 19115 (MD_RestrictionCode codelist) or default "None"
  "wms_contactorganization" "MapServer"   #responsible organization
  "wms_contactposition" "owner"           #responsible organization, value according "INSPIRE Metadata Regulation" (part D6)
  ...
 END
END

Notes:

  • several fields require certain values, these values are not validated by MapServer itself, instead a manual validation against the INSPIRE schemas or the WMS INSPIRE tester is recommended
  • as suggested in this document regarding scenario 2, <inspire_common:ResourceType> is always set to service and <inspire_common:SpatialDataServiceType> is always set to view, both values can’t be altered through the mapfile
  • conformity is always set to not evaluated, based on the latest INSPIRE Metadata Implementing Rules (page 7), a specification document, the specification date and a specification URI or URL need to be provided for degree conformant/not conformant, which is currently not implemented

5. Named group layers

INSPIRE mandates usage of named group layers. Thus the functionality of wms_layer_group is extended to support named group layers. If a layer with the same name as used in wms_layer_group is found it is treated as named group if no layer with this name is found as unnamed group as before.

To provide this functionality the variable isUsedInNestedGroup is introduced in methods msWMSPrepareNestedGroups() and msWMSPrintNestedGroups() which is used in the various methods to prepare WMS responses e.g. msWMSGetCapabilities().

Provided that ability, a hierarchy of any level can be achieved. See the „wms_inspire.map“ mapfile in msautotest for an example.

TN
+--- TN.CommonTransportElements
     +--- TN.CommonTransportElements.TransportArea
     +--- TN.CommonTransportElements.TransportLink
     +--- TN.CommonTransportElements.TransportNode
+--- TN.RoadTransportNetwork
     +--- TN.RoadTransportNetwork
     +--- TN.RoadTransportNetwork.VehicleTrafficArea
     +--- TN.RoadTransportNetwork.RoadServiceArea
     +--- TN.RoadTransportNetwork.RoadArea
+--- TN.RailTransportNetwork
     +--- TN.RailTransportNetwork.RailwayLink
     +--- TN.RailTransportNetwork.RailwayStationArea
     +--- TN.RailTransportNetwork.RailwayYardArea
     +--- TN.RailTransportNetwork.RailwayArea

6. Style section for root layer and possibly existing group layers

For regular layers, the concept of GROUP and CLASSGROUP can be used to set the layer style name to the according value. Additionally - as suggested in Ticket 3850 - the layer style titles can be overwritten through wms_style_<stylename>_title and the layer style legendURLs through wms_style_<stylename>_legendurl_* (width, height, format and href need to be provided).

...
       LAYER
        NAME TN.RoadTransportNetwork.RoadLink
        DATA "road"
        METADATA
         "wms_title.eng" "Transport networks: Road Link"
         "wms_title.ger" "Verkehrsnetze: Strassensegment"
         ...
         "wms_style_inspire_common:DEFAULT_title" "mylayerstyletitle"         #style title
         "wms_style_inspire_common:DEFAULT_legendurl_width" "85"              #override style legendurl (mandatory: width, height, format, href)
         "wms_style_inspire_common:DEFAULT_legendurl_height" "40"
         "wms_style_inspire_common:DEFAULT_legendurl_format" "image/png"
         "wms_style_inspire_common:DEFAULT_legendurl_href" "http://path/to/onlineresource...roadlink"
        END
        ...
       END
       ...
       CLASSGROUP "inspire_common:DEFAULT"
       CLASSITEM "NAME_E"

       CLASS
        NAME "myclass1"
        GROUP "inspire_common:DEFAULT"
        EXPRESSION "Trans-Canada Highway"
        COLOR 255 0 0
       END

       CLASS
        NAME "myclass2"
        GROUP "inspire_common:DEFAULT"
        COLOR 0 255 0
       END
...

The following method is suggested to support (customizable) style sections in the root layer

  • use wms_style_name in the WEB.METADATA section to add a style section to the root layer
  • use wms_style_title to override the style title (optional)
  • use wms_style_legendurl_* to override width, height, format and href of the legendURL (optional)

and possibly existing group layers

  • use wms_group_style_name in the first corresponding LAYER.METADATA section to add a style section to the group layer
  • use wms_group_style_title to override the style title (optional)
  • use wms_group_style_legendurl_* to override width, height, format and href of the legendURL (optional)
...
       WEB
        METADATA
         ...
         "wms_style_name" "inspire_common:DEFAULT"      #style name
         "wms_style_title" "myroadarealayerstyletitle"  #style title
         "wms_style_legendurl_width" "85"               #override style legendurl (mandatory: width, height, format, href)
         "wms_style_legendurl_height" "40"
         "wms_style_legendurl_format" "image/png"
         "wms_style_legendurl_href" "http://path/to/onlineresource...roadarea"
        END
       END

       LAYER
        NAME TN.RailTransportNetwork.RailwayLink
        GROUP TN.CommonTransportElements.TransportLink
         DATA "road"
         METADATA
          "wms_group_title.eng" "Transport networks: Generic Transport Link"
          "wms_group_title.ger" "Verkehrsnetze: Generisches Verkehrssegment"
          "wms_group_abstract" "mygenerictransportlinklayerabstract" #fallback
          "wms_group_abstract.ger" "mygenerictransportlinklayerabstract"
          "wms_group_style_name" "inspire_common:DEFAULT" #style name
          "wms_group_style_title" "mygenerictransportlinklayerstyletitle" #style title
          "wms_group_style_legendurl_width" "85"        #override style legendurl (mandatory: width, height, format, href)
          "wms_group_style_legendurl_height" "40"
          "wms_group_style_legendurl_format" "image/png"
          "wms_group_style_legendurl_href" "http://path/to/onlineresource...generictransportlink"
          "wms_title.eng" "Transport networks: Railway Link"
          "wms_title.ger" "Verkehrsnetze: Eisenbahnverbindung"
          "wms_abstract" "myrailwaylinklayerabstract"   #fallback
          "wms_abstract.ger" "myrailwaylinklayerabstractger"
          ...
         END
        ...
       END
...

Provided that ability, 3 levels of hierarchy can be achieved as done in the example mapfiles „wms_inspire_scneario1.map“ and „wms_inspire_scneario2.map“ in msautotest.

TN.RoadTransportNetwork.RoadArea
+--- TN.RoadTransportNetwork.RoadLink
+--- TN.CommonTransportElements.TransportLink
     +--- TN.RailTransportNetwork.RailwayLink
     +--- TN.AirTransportNetwork.AirLink

7. Implementation details

In order to implement these enhancements, the following changes need to be implemented in the MapServer codebase:

  1. get language from request and validate it
  2. detect if INSPIRE support is activated, if so add corresponding namespace
  3. output extended capabilitities with language list and INSPIRE specific metadata (depending on scenario 1 or 2)
  4. add language parameter to onlineresource in output
  5. consider key extension based on language (e.g. „wms_title.eng“) when deriving metadata from the mapobject, use fallback with no extension (e.g. „wms_title“)
  6. group layers according to „wms_layer_group“
  7. override style titles and legendURLs if specified in mapfile (e.g. „wms_style_<stylename>_title“)
  8. add warnings for missing but mandatory INSPIRE specific metadata
  9. include information from any nested layers in various request types

7.1 Files affected

The following files are affected by this RFC:

mapows.c/mapows.h

[N] MS_DLL_EXPORT const char *msOWSLookupMetadataWithLanguage(.., const char *validated_language)
[N] MS_DLL_EXPORT char *msOWSGetOnlineResource2(.., const char *validated_language)
[N] MS_DLL_EXPORT char **msOWSGetInspireLanguageList(..)
[N] MS_DLL_EXPORT char *msOWSGetInspireLanguage(.., const char *requested_language)
[N] MS_DLL_EXPORT int msOWSPrintInspireCommonExtendedCapabilities(..)
[N] int msOWSPrintInspireCommonMetadata(..)
[N] int msOWSPrintInspireCommonLanguages(..)
[C] int msOWSPrintEncodeMetadata(..)
[N] int msOWSPrintEncodeMetadata2(.., const char *validated_language)
[C] int msOWSPrintGroupMetadata(..)
[N] int msOWSPrintGroupMetadata2(.., const char *validated_language)
[C] int msOWSPrintMetadataList(..)
[C] int msOWSPrintEncodeMetadataList(..)

mapwms.c

[S] int msDumpLayer(.., const char *validated_language, int grouplayer)
[S] void msWMSPrepareNestedGroups(.., int* isUsedInNestedGroup)
[S] void msWMSPrintNestedGroups(.., int* isUsedInNestedGroup, const char *validated_language)
[S] int msWMSGetCapabilities(.., const char *requested_language)
[C] int msWMSLoadGetMapParams(..)
[C] int msWMSFeatureInfo(..)
[C] int msWMSDescribeLayer(..)
[C] int msWMSGetLegendGraphic(..)
[C] int msWMSGetStyles(..)
[C] int msWMSDispatch(..)
[N] void msWMSPrintAuthorityURL(..)
[N] void msWMSPrintIdentifier(..)
[N] void msWMSPrintKeywordlist(..)

mapdraw.c

[C] int msLayerIsVisible(..)

maputil.c

[C] int msExtentsOverlap(..)
  • [C] function changed
  • [N] new function
  • [S] signature of function also changed

7.2 MapScript issues

This changes provide new functionality with no MapScript issues being considered.

7.3 Backwards compatibility issues

This change provides new functionality with no backwards compatibility issues being considered.

8. Solution

The code for this RFC can be found in the inspire_soc2011 sandbox.

Incorporated tickets:
  • Ticket 3608: INSPIRE related support
  • Ticket 3850: allow to define a title for styles and possibility to override autogenerated legendurl href
  • Ticket 1632: support for named group layers using wms_layer_group
  • Ticket 4129: root layer metadata
  • Ticket 4148: WMS GetFeatureInfo has wrong content-type
  • Ticket 4149: wrong default WMS LegendUrl image format
  • Ticket 4151: add vocabulary attribute to keywords in capabilities document
  • Ticket 4144: GetLegendGraphic should work without OGR compiled
  • Ticket 4126: copyright (annotation) layer inside data extent only

9. Tests

3 example mapfiles were created for testing purposes:

The GetCapabilities responses with these mapfiles validate against the INSPIRE schemas as well as the WMS INSPIRE tester without any critical warnings or errors.

10. Voting history

Adopted on 2012/03/08 with +1 from FrankW, SteveL, and DanielM and +0 from SteveW.