Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/forum/config/optional/rdf.mapping.node.forum.yml

@@ -0,0 +1,38 @@
+id: node.forum
+targetEntityType: node
+bundle: forum
+types:
+  - 'schema:Discussion'
+fieldMappings:
+  title:
+    properties:
+      - 'schema:name'
+  created:
+    properties:
+      - 'schema:dateCreated'
+    datatype_callback:
+      callable: 'Drupal\rdf\CommonDataConverter::dateIso8601Value'
+  changed:
+    properties:
+      - 'schema:dateModified'
+    datatype_callback:
+      callable: 'Drupal\rdf\CommonDataConverter::dateIso8601Value'
+  body:
+    properties:
+      - 'schema:text'
+  uid:
+    properties:
+      - 'schema:author'
+    mapping_type: 'rel'
+  comment_count:
+    properties:
+      - 'schema:interactionCount'
+    datatype_callback:
+      callable: 'Drupal\rdf\SchemaOrgDataConverter::interactionCount'
+      arguments:
+        interaction_type: 'UserComments'
+dependencies:
+  config:
+    - node.type.forum
+  module:
+    - node

core/modules/forum/config/optional/rdf.mapping.taxonomy_term.forums.yml

@@ -0,0 +1,18 @@
+id: taxonomy_term.forums
+targetEntityType: taxonomy_term
+bundle: forums
+types:
+  - 'sioc:Container'
+  - 'sioc:Forum'
+fieldMappings:
+  name:
+    properties:
+      - 'schema:name'
+  description:
+    properties:
+      - 'schema:description'
+dependencies:
+  config:
+    - taxonomy.vocabulary.forums
+  module:
+    - taxonomy