ONOS-3655 - Adding Junit tests for DeviceKey subsystem, and adding DeviceKey
event, listener, store and delegate classes.  DeviceKeyManager and store
implementation will be added in the next submission.

Change-Id: I60edb1753e9ee2985ccabc2b6ec9c223867590de
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/key/DeviceKeyEvent.java b/incubator/api/src/main/java/org/onosproject/incubator/net/key/DeviceKeyEvent.java
new file mode 100644
index 0000000..8c2acb4
--- /dev/null
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/key/DeviceKeyEvent.java
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2016 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.incubator.net.key;
+
+import com.google.common.annotations.Beta;
+import org.onosproject.event.AbstractEvent;
+
+/**
+ * Describes device key events.
+ */
+@Beta
+public class DeviceKeyEvent extends AbstractEvent<DeviceKeyEvent.Type, DeviceKey> {
+
+    /**
+     * Type of device key events.
+     */
+    public enum Type {
+        /**
+         * Signals that a new device key has been added.
+         */
+        DEVICE_KEY_ADDED,
+
+        /**
+         * Signals that a device key has been updated or changed state.
+         */
+        DEVICE_KEY_UPDATED,
+
+        /**
+         * Signals that a device key has been removed.
+         */
+        DEVICE_KEY_REMOVED
+    }
+
+    /**
+     * Creates an event of a given type, and for the specified device key.
+     *
+     * @param type      device key event type
+     * @param deviceKey event device key subject
+     */
+    public DeviceKeyEvent(Type type, DeviceKey deviceKey) {
+        super(type, deviceKey);
+    }
+
+    /**
+     * Creates an event of a given type, for the specified device key, and
+     * the current time.
+     *
+     * @param type      device key event type
+     * @param deviceKey event device key subject
+     * @param time      occurrence time
+     */
+    public DeviceKeyEvent(Type type, DeviceKey deviceKey, long time) {
+        super(type, deviceKey, time);
+    }
+}
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/key/DeviceKeyListener.java b/incubator/api/src/main/java/org/onosproject/incubator/net/key/DeviceKeyListener.java
new file mode 100644
index 0000000..c9268a4
--- /dev/null
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/key/DeviceKeyListener.java
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2016 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.incubator.net.key;
+
+import com.google.common.annotations.Beta;
+import org.onosproject.event.EventListener;
+
+/**
+ * Listener for device key related events.
+ */
+@Beta
+public interface DeviceKeyListener extends EventListener<DeviceKeyEvent> {
+}
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/key/DeviceKeyStore.java b/incubator/api/src/main/java/org/onosproject/incubator/net/key/DeviceKeyStore.java
new file mode 100644
index 0000000..f25b662
--- /dev/null
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/key/DeviceKeyStore.java
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2016 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.incubator.net.key;
+
+import com.google.common.annotations.Beta;
+import org.onosproject.store.Store;
+
+/**
+ * Manages inventory of device keys; not intended for direct use.
+ */
+@Beta
+public interface DeviceKeyStore extends Store<DeviceKeyEvent, DeviceKeyStoreDelegate> {
+    /**
+     * Creates or updates a device key.
+     *
+     * @param deviceKey device key
+     * @return device key event
+     */
+    DeviceKeyEvent createOrUpdateDeviceKey(DeviceKey deviceKey);
+
+    /**
+     * Deletes a device key by a specific device key identifier.
+     *
+     * @param deviceKeyId device key unique identifier
+     * @return device key event
+     */
+    DeviceKeyEvent deleteDeviceKey(DeviceKeyId deviceKeyId);
+}
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/key/DeviceKeyStoreDelegate.java b/incubator/api/src/main/java/org/onosproject/incubator/net/key/DeviceKeyStoreDelegate.java
new file mode 100644
index 0000000..0ae7b85
--- /dev/null
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/key/DeviceKeyStoreDelegate.java
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2016 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.incubator.net.key;
+
+import com.google.common.annotations.Beta;
+import org.onosproject.store.StoreDelegate;
+
+/**
+ * Device key store delegate abstraction.
+ */
+@Beta
+public interface DeviceKeyStoreDelegate extends StoreDelegate<DeviceKeyEvent> {
+}