INSPIRE-compliant data/metadata coupling with deegree 3

INSPIRE sets a high value on metadata and coupling of data and metadata. For example, the GetCapabilities response of an INSPIRE-compliant View Service links every offered layer to the corresponding ISO/INSPIRE metadata record (which is usually served by an INSPIRE Discovery Service). An example snippet from a Layer element (nested in a WMS capabilities document) could look like this:

In order to support the generation of these MetadataURL elements, deegree WMS and WFS configurations now support the new options MetadataURLTemplate and MetadataSetId:

<deegreeWMS [...]>

  <MetadataURLTemplate>http://discovery.eu/csw?service=CSW\
    &request=GetRecordById&version=2.0.2&id=${metadataSetId}\
    &outputSchema=http://www.isotc211.org/2005/gmd\
    &elementSetName=full
  </MetadataURLTemplate>

  [...]
  <RequestableLayer>
    <Name>AU.AdministrativeUnit</Name>
    <Title>Administrative unit</Title>
    <Abstract>...</Abstract>
    [...]
    <MetadataSetId>550e8400-e29c-11d4-a716-446655440000
    </MetadataSetId>
    [...]
  </RequestableLayer>
  [...]

</deegreeWMS>

The global MetadataURLTemplate element provides a template for generating URLs of ISO metadata records. In the example, this is a KVP-encoded GetRecordById request template to a CSW instance. Every layer (for WFS: feature type) in the configuration can carry a MetadataSetId element to define the actual metadata record identifier (usually a UUID). This allows deegree WMS to generate the MetadataURL element in the GetCapabilities response.

Advanced options:

• If one omits the MetadataURLTemplate element, deegree will assume that you want to generate URLs that point back to the deegree CSW instance on the same endpoint as the WMS/WFS (deegree offers an INSPIRE-compliant CSW as well). 
• MetadataStoreId: If this global element is specified, deegree will access the internal metadata store with the specified id to retrieve the metadata record and magically augment the layer metadata reported in the capabilities. For instance, the Title and Abstract elements can be populated this way. Currently, this only makes sense if the same deegree instance hosts the CSW with the metadata records, but we’re working on enabling the access to any ISO/INSPIRE compliant CSW for retrieving the metadata.

For now, the new configuration options provide a first option to generate the MetadataURLs required by INSPIRE. In the near future, real integration between WMS/WFS and CSW should ease metadata configuration for GetCapabilities responses. If a CSW/INSPIRE Discovery Service is available to provide proper service and data metadata, every applicable piece of metadata (Title, Abstract, Keywords, …) should be automatically imported and reused for generating the GetCapabilities responses of deegree WMS and WFS.