diff --git oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/spi/IndexDescription.java oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/spi/IndexDescription.java
new file mode 100644
index 0000000..5c97470
--- /dev/null
+++ oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/spi/IndexDescription.java
@@ -0,0 +1,75 @@
+package org.apache.jackrabbit.oak.plugins.index.lucene.spi;
+
+import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
+
+/**
+ * An immutable description of an index definition. The IndexDescription
+ * is an API agnostic description of a hierarchy, which can describe both
+ * NodeState hierarchies as well as JCR Node hierarchies.
+ * <br>
+ * It is used by {@link IndexableFieldProvider}s to learn about the
+ * definition of an index for which they could provide fields.
+ */
+public interface IndexDescription {
+
+    /**
+     * Allow exploratory access to an IndexDescription instance.
+     *
+     * @return The names of the keys of all values of this instance.
+     */
+    @Nonnull
+    Iterable<String> keys();
+
+    /**
+     * Allow querying for existence of a key.
+     *
+     * @return Whether or not an entry with the given key exists.
+     */
+    boolean hasKey(@Nonnull String key);
+
+    /**
+     * Type-safe accessor to retrieve a value given a key. If the key
+     * does not exist, the defaultValue is returned.
+     * <br>
+     * To check for existence of a key use {@link #hasKey(String)}.
+     * <br>
+     * If the key maps to a value that is not the same as the defaultValue,
+     * an implementation may try to coerce the value to the defaultValue's
+     * type. If this fails, an IllegalArgumentException is thrown.
+     *
+     * @param key The name of the key.
+     * @param defaultValue The value to return if the key does not exist.
+     * @param <T> The type of the value to be returned is the same as the defaultValue's type.
+     * @return The value for the given key or the defaultValue.
+     * @throws IllegalArgumentException if the value mapped to by the key cannot be coerced to
+     *         the type of the default value.
+     */
+    @Nonnull
+    <T> T getWithDefault(@Nonnull String key, @Nonnull T defaultValue);
+
+    /**
+     * Allow exploratory access to the names of all children.
+     *
+     * @return The names of all existing children.
+     */
+    @Nonnull
+    Iterable<String> getChildNames();
+
+    /**
+     * Allow querying for the existence of a child.
+     *
+     * @param name The name of the child.
+     * @return Whether or not a child of the given name exists.
+     */
+    boolean hasChild(@Nonnull String name);
+
+    /**
+     * Allow retrieving a child by its name.
+     *
+     * @param name The name of the child.
+     * @return The child if it exists, otherwise null.
+     */
+    @CheckForNull
+    IndexDescription getChild(@Nonnull String name);
+}
diff --git oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/spi/IndexableFieldProvider.java oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/spi/IndexableFieldProvider.java
new file mode 100644
index 0000000..6777422
--- /dev/null
+++ oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/spi/IndexableFieldProvider.java
@@ -0,0 +1,51 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.jackrabbit.oak.plugins.index.lucene.spi;
+
+import org.apache.jackrabbit.oak.spi.state.NodeState;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.index.IndexableField;
+
+import javax.annotation.Nonnull;
+
+/**
+ * An IndexableFieldProvider may provide Lucene {@link Field}s to be indexed by
+ * the index described by the {@code IndexDescription} for a given {@code NodeState}
+ * at a given path.
+ */
+public interface IndexableFieldProvider {
+    /**
+     * LuceneIndexEditor calls this method for each NodeState that should be indexed.
+     * An IndexDescription allows quick access to properties of the index definition,
+     * which may be used by an implementation to determine what to do, e.g. whether
+     * it should act at all for the given index or not.
+     * <br>
+     * The IndexableFieldProvider may choose to index any or all properties of the
+     * given NodeState.
+     *
+     * @param description A description of the index definition.
+     * @param nodeState The NodeState to be indexed.
+     * @param path The path of given NodeState.
+     * @return An Iterable with all IndexableFields provided by this instance. If no
+     *         fields are provided this must be an empty Iterable.
+     */
+    @Nonnull
+    Iterable<IndexableField> provideFields(
+            @Nonnull IndexDescription description, @Nonnull NodeState nodeState, @Nonnull String path);
+}