diff --git a/core/api/src/main/java/org/onosproject/net/flowobjective/FilteringObjective.java b/core/api/src/main/java/org/onosproject/net/flowobjective/FilteringObjective.java
index 24ca2dc..d892a97 100644
--- a/core/api/src/main/java/org/onosproject/net/flowobjective/FilteringObjective.java
+++ b/core/api/src/main/java/org/onosproject/net/flowobjective/FilteringObjective.java
@@ -41,6 +41,13 @@
     }
 
     /**
+     * Obtain the key for this filter.
+     *
+     * @return a criterion
+     */
+    public Criterion key();
+
+    /**
      * Obtain this filtering type.
      * @return the type
      */
@@ -59,6 +66,14 @@
     public interface Builder extends Objective.Builder {
 
         /**
+         * Specify the key for the filter.
+         *
+         * @param key a criterion
+         * @return a filter objective builder
+         */
+        public Builder withKey(Criterion key);
+
+        /**
          * Add a filtering condition.
          *
          * @param criterion new criterion