Flow Objective implementation

Provides an abstraction which isolates the application from any pipeline
knowledge. By using the provided objectives applications can express
their forwarding desires in a pipeline agnostic way. The objectives
are then consumed by a driver for the specific device who converts them
into the appropriate pipeline coherent flows.

Change-Id: I74a68b4971c367c0cd5b7de9d877abdd117afa98
diff --git a/core/api/src/main/java/org/onosproject/net/behaviour/NextGroup.java b/core/api/src/main/java/org/onosproject/net/behaviour/NextGroup.java
new file mode 100644
index 0000000..b5a3891
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/behaviour/NextGroup.java
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed 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.onosproject.net.behaviour;
+
+/**
+ * Opaque data type for carrying group-like information.
+ * Only relevant to a pipeliner driver.
+ */
+public interface NextGroup {
+
+    /**
+     * Serialized form of the next group.
+     * @return a byte array.
+     */
+    byte[] data();
+
+}