diff --git a/core/modules/jsonld/lib/Drupal/jsonld/JsonldEntityNormalizer.php b/core/modules/jsonld/lib/Drupal/jsonld/JsonldEntityNormalizer.php
index 3d0437d..f6cc9ed 100644
--- a/core/modules/jsonld/lib/Drupal/jsonld/JsonldEntityNormalizer.php
+++ b/core/modules/jsonld/lib/Drupal/jsonld/JsonldEntityNormalizer.php
@@ -60,7 +60,7 @@ public function denormalize($data, $class, $format = null) {
     try {
       $typedDataIds = $this->rdfMappingManager->getTypedDataIds($typeUris);
     } catch (RdfMappingException $e) {
-      throw new UnexpectedValueException($e->getMessage());
+      throw new UnexpectedValueException($e->getMessage(), 0, $e);
     }
 
     $values = array(
diff --git a/core/modules/jsonld/lib/Drupal/jsonld/JsonldEntityWrapper.php b/core/modules/jsonld/lib/Drupal/jsonld/JsonldEntityWrapper.php
index 24027a3..4a5864a 100644
--- a/core/modules/jsonld/lib/Drupal/jsonld/JsonldEntityWrapper.php
+++ b/core/modules/jsonld/lib/Drupal/jsonld/JsonldEntityWrapper.php
@@ -89,17 +89,17 @@ public function getId() {
    * of simply returning the site schema URI.
    */
   public function getTypeUri() {
-    $entityType = $this->entity->entityType();
+    $entity_type = $this->entity->entityType();
     $bundle = $this->entity->bundle();
     switch ($this->format) {
       case 'drupal_jsonld':
-        $schemaPath = SiteSchema::CONTENT_DEPLOYMENT;
+        $schema_path = SiteSchema::CONTENT_DEPLOYMENT;
         break;
       case 'jsonld':
-        $schemaPath = SiteSchema::SYNDICATION;
+        $schema_path = SiteSchema::SYNDICATION;
     }
-    $schema = $this->siteSchemaManager->getSchema($schemaPath);
-    return $schema->bundle($entityType, $bundle)->getUri();
+    $schema = $this->siteSchemaManager->getSchema($schema_path);
+    return $schema->bundle($entity_type, $bundle)->getUri();
   }
 
   /**
diff --git a/core/modules/rdf/lib/Drupal/rdf/RdfMappingException.php b/core/modules/rdf/lib/Drupal/rdf/RdfMappingException.php
index f958e25..599ad1c 100644
--- a/core/modules/rdf/lib/Drupal/rdf/RdfMappingException.php
+++ b/core/modules/rdf/lib/Drupal/rdf/RdfMappingException.php
@@ -6,9 +6,7 @@
 
 namespace Drupal\rdf;
 
-use Exception;
-
 /**
  * Exception to use when no RDF mapping is found.
  */
-class RdfMappingException extends Exception { }
+class RdfMappingException extends \Exception { }
diff --git a/core/modules/rdf/lib/Drupal/rdf/SiteSchema/BundleSchema.php b/core/modules/rdf/lib/Drupal/rdf/SiteSchema/BundleSchema.php
index 8277770..d799404 100644
--- a/core/modules/rdf/lib/Drupal/rdf/SiteSchema/BundleSchema.php
+++ b/core/modules/rdf/lib/Drupal/rdf/SiteSchema/BundleSchema.php
@@ -15,7 +15,12 @@
  */
 class BundleSchema extends EntitySchema {
 
-  const URI_PATTERN = '{entity_type}/{bundle}';
+  /**
+   * The URI pattern for bundle site schema terms.
+   *
+   * @var string
+   */
+  public static $uriPattern = '{entity_type}/{bundle}';
 
   /**
    * The bundle that this term identifies.
@@ -43,7 +48,7 @@ public function __construct($siteSchema, $entity_type, $bundle) {
    * Implements \Drupal\rdf\SiteSchema\SchemaTermBase::getUri().
    */
   public function getUri() {
-    $path = str_replace(array('{entity_type}', '{bundle}'), array($this->entityType, $this->bundle), self::URI_PATTERN);
+    $path = str_replace(array('{entity_type}', '{bundle}'), array($this->entityType, $this->bundle), static::$uriPattern);
     return $this->siteSchema->getUri() . $path;
   }
 
diff --git a/core/modules/rdf/lib/Drupal/rdf/SiteSchema/EntitySchema.php b/core/modules/rdf/lib/Drupal/rdf/SiteSchema/EntitySchema.php
index bc602ee..36ec5c4 100644
--- a/core/modules/rdf/lib/Drupal/rdf/SiteSchema/EntitySchema.php
+++ b/core/modules/rdf/lib/Drupal/rdf/SiteSchema/EntitySchema.php
@@ -15,7 +15,12 @@
  */
 class EntitySchema extends SchemaTermBase {
 
-  const URI_PATTERN = '{entity_type}';
+  /**
+   * The URI pattern for entity site schema terms.
+   *
+   * @var string
+   */
+  public static $uriPattern = '{entity_type}';
 
   /**
    * The entity type that this term identifies.
@@ -52,7 +57,7 @@ public function getGraph() {
    * Implements \Drupal\rdf\SiteSchema\SchemaTermBase::getUri().
    */
   public function getUri() {
-    $path = str_replace('{entity_type}', $this->entityType , self::URI_PATTERN);
+    $path = str_replace('{entity_type}', $this->entityType , static::$uriPattern);
     return $this->siteSchema->getUri() . $path;
   }
 
diff --git a/core/modules/rdf/lib/Drupal/rdf/SiteSchema/SchemaTermBase.php b/core/modules/rdf/lib/Drupal/rdf/SiteSchema/SchemaTermBase.php
index bc4165d..f24bf57 100644
--- a/core/modules/rdf/lib/Drupal/rdf/SiteSchema/SchemaTermBase.php
+++ b/core/modules/rdf/lib/Drupal/rdf/SiteSchema/SchemaTermBase.php
@@ -8,12 +8,18 @@
 namespace Drupal\rdf\SiteSchema;
 
 use Drupal\rdf\RdfConstants;
-use Drupal\rdf\SiteSchema\SiteSchema;
 
 /**
  * Base class to define an RDF term in a schema.
  */
-abstract class SchemaTermBase {
+abstract class SchemaTermBase implements SchemaTermInterface {
+
+  /**
+   * The URI pattern for this type of site schema term.
+   *
+   * @var string
+   */
+  public static $uriPattern;
 
   /**
    * The schema in which this term is defined.
@@ -33,17 +39,6 @@ public function __construct($siteSchema) {
   }
 
   /**
-   * Get the full graph of terms and properties to display.
-   *
-   * When an RDF term URI is dereferenced, it usually contains a description of
-   * the term in RDF. To make it easier to use this description, include
-   * information about all related terms. For example, when viewing the RDF
-   * description for the RDF class which corresponds to a Drupal bundle, data
-   * about its fields would also be included.
-   */
-   abstract public function getGraph();
-
-  /**
    * Get the term properties.
    *
    * @return array
@@ -55,15 +50,4 @@ public function getProperties() {
     );
   }
 
-  /**
-   * Get the URI of the term.
-   *
-   * Implementations of this method will use the URI patterns defined in
-   * URI_PATTERN constants and replace placeholders with actual values.
-   *
-   * @return string
-   *   The URI of the term.
-   */
-  abstract public function getUri();
-
 }
diff --git a/core/modules/rdf/lib/Drupal/rdf/SiteSchema/SchemaTermInterface.php b/core/modules/rdf/lib/Drupal/rdf/SiteSchema/SchemaTermInterface.php
new file mode 100644
index 0000000..7b841f1
--- /dev/null
+++ b/core/modules/rdf/lib/Drupal/rdf/SiteSchema/SchemaTermInterface.php
@@ -0,0 +1,43 @@
+<?php
+
+/**
+ * Contains SchemaTermInterface.
+ */
+
+namespace Drupal\rdf\SiteSchema;
+
+interface SchemaTermInterface {
+
+  /**
+   * Get the full graph of terms and properties to display.
+   *
+   * When an RDF term URI is dereferenced, it usually contains a description of
+   * the term in RDF. To make it easier to use this description, include
+   * information about all related terms. For example, when viewing the RDF
+   * description for the RDF class which corresponds to a Drupal bundle, data
+   * about its fields would also be included.
+   *
+   * @return array
+   *   An array of terms and their properties, keyed by term URI.
+   */
+  public function getGraph();
+
+  /**
+   * Get the term properties.
+   *
+   * @return array
+   *   An array of properties for this term, keyed by URI.
+   */
+  public function getProperties();
+
+  /**
+   * Get the URI of the term.
+   *
+   * Implementations of this method will use the URI patterns defined in
+   * $uriPattern static variables and replace placeholders with actual values.
+   *
+   * @return string
+   *   The URI of the term.
+   */
+  public function getUri();
+}
diff --git a/core/modules/rdf/lib/Drupal/rdf/SiteSchema/SiteSchema.php b/core/modules/rdf/lib/Drupal/rdf/SiteSchema/SiteSchema.php
index 063906e..0bdf5d9 100644
--- a/core/modules/rdf/lib/Drupal/rdf/SiteSchema/SiteSchema.php
+++ b/core/modules/rdf/lib/Drupal/rdf/SiteSchema/SiteSchema.php
@@ -77,7 +77,7 @@ public function getPath() {
    */
   public function getRoutes() {
     return array(
-      'bundle' => $this->schemaPath . BundleSchema::URI_PATTERN,
+      'bundle' => $this->schemaPath . BundleSchema::$uriPattern,
     );
   }
 }