Metadata Query Service (MDQ)

A Metadata Query Service can be queried for the metadata of individual entities (IdP/SP/Attribute Authority) in real-time. This approach is also called Per-Entity Metadata. The conventional approach is to offer federation metadata as huge xml files that have to be fetched, validated and processed by all participating systems. The per-entity approach consumes much less resources: All systems just process the metadata they need in a given moment, and cache them for a certain time. This procedure is based on the Metadata Query Protocol (see References).

A Metadata Query Service has to meet high requirements in terms of availability and resilience. DFN-AAI's pilot lets us gain experience and improve the service for production.

Please note

Beachten Sie bitte auch die weiteren Hinweise unten.

Important notice: The MDQ service does not deliver any local metadata! You still have to include them via a static metadata provider, type FileBackedHTTPMetadataProvider for Shibboleth IdPs, type XML for Shibboleth SPs.

URL for the production metadata (DFN-AAI, DFN-AAI-Basic) and eduGAIN:

http(s)://mdq.aai.dfn.de

URL for the metadata of the test federation (DFN-AAI-Test):

http(s)://mdq-test.aai.dfn.de

Certificate for the validation of the signature of DFN-AAI MDQ Metadata (PEM format)
SHA256 Fingerprint: 73:5B:9E:76:8A:A6:33:73:4D:3E:C6:D2:1E:98:B3:D9:03:74:B9:87:16:52:16:53:32:26:9A:B2:55:FC:CA:D2
https://www.aai.dfn.de/fileadmin/metadata/dfn-aai-mdq.pem

./conf/metadata-providers.xml

    <MetadataProvider id="dfn_aai_mdq_prod" xsi:type="DynamicHTTPMetadataProvider"
                  maxCacheDuration="PT1H" minCacheDuration="PT10M">
           <MetadataFilter xsi:type="SignatureValidation" requireSignedRoot="true"
                  certificateFile="/etc/ssl/aai/dfn-aai-mdq.pem"/>
           <MetadataQueryProtocol>http://mdq.aai.dfn.de</MetadataQueryProtocol>
    </MetadataProvider>

./conf/metadata-providers.xml

    <MetadataProvider id="dfn_aai_mdq_test" xsi:type="DynamicHTTPMetadataProvider"
                  maxCacheDuration="PT1H" minCacheDuration="PT10M">
           <MetadataFilter xsi:type="SignatureValidation" requireSignedRoot="true"
                  certificateFile="/etc/ssl/aai/dfn-aai-mdq.pem"/>
           <MetadataQueryProtocol>http://mdq-test.aai.dfn.de</MetadataQueryProtocol>
    </MetadataProvider>

We are happy to document further filter mechanisms on demand.

/etc/shibboleth/shibboleth2.xml

    <MetadataProvider type="MDQ" id="dfn_aai_mdq_prod" ignoreTransport="true"
                  cacheDirectory="mdq-aai-dfn-de"
                  maxCacheDuration="3600" minCacheDuration="600"
                  baseUrl="https://mdq.aai.dfn.de">
           <MetadataFilter type="Signature" certificate="/etc/ssl/aai/dfn-aai-mdq.pem"/>
    </MetadataProvider>

(Zur Unterscheidung zwischen “Advanced” und “Basic” siehe die Erläuterungen zu den Verlässlichkeitsklassen)

Wichtig: damit der u.g. Filter funktioniert, muss im Root-Element SPConfig der Datei shibboleth2.xml der Namespace xmlns:saml=“urn:oasis:names:tc:SAML:2.0:assertion” gesetzt sein.

/etc/shibboleth/shibboleth2.xml

    <MetadataProvider type="MDQ" id="dfn_aai_mdq_advanced_only" ignoreTransport="true"
                  cacheDirectory="mdq-aai-dfn-de"
                  maxCacheDuration="3600" minCacheDuration="600"
                  baseUrl="https://mdq.aai.dfn.de">
           <MetadataFilter type="Signature" certificate="/etc/ssl/aai/dfn-aai-mdq.pem"/>
           <MetadataFilter type="Include" matcher="EntityAttributes">
               <saml:Attribute Name="http://aai.dfn.de/loa/degree-of-reliance" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri">
                 <saml:AttributeValue>advanced</saml:AttributeValue>
               </saml:Attribute>
           </MetadataFilter>
    </MetadataProvider>

Weitere Filtermöglichkeiten werden gerne auf Anfrage dokumentiert.

Allgemein:
Sofern in der Metadata Provider Konfiguration weitere, 'statische' (z.B. FileBackedHTTPMetadataProvider) MetadataProvider definiert sind, sollten MetadataProvider-Elemente des Typs das MDQ bzw. DynamicHTTPMetadataProvider ganz am Ende eingefügt werden. Ansonsten führt der IdP/SP jedes Mal eine Metadata Query aus, auch wenn die betreffende Entity bereits über die statischen Metadaten verfügbar ist.

Shibboleth IdP:
Bei nicht erfolgreichen Metadata Queries erscheint eine Warnung im Log: Document root was not an EntityDescriptor: org.opensaml.saml.saml2.metadata.impl.EntitiesDescriptorImpl

Shibboleth SP < 3.2.0:
Im SP-Log erscheint nach jedem Neustart die irreführende Warnung, dass das Caching-Verzeichnis nicht nicht angelegt werden kann. Es existiert bereits. Siehe https://issues.shibboleth.net/jira/browse/SSPCPP-916

Sonstige Fehler bitte an hotline@aai.dfn.de melden.

• Spezifikation Metadata Query Protocol
• Shibboleth Wiki
  • Metadata Management Best Practices
  • Konfiguration Identity Provider
  • Konfiguration Service Provider
• Ausführliche Doku im InCommon Wiki (US-Föderation)