[ONOS-7566] Implementation of NetconfProxySession

Change-Id: I01cbe0b10ac36cb6db53127555b551f405acdeb1
diff --git a/protocols/netconf/api/src/main/java/org/onosproject/netconf/NetconfProxyMessage.java b/protocols/netconf/api/src/main/java/org/onosproject/netconf/NetconfProxyMessage.java
new file mode 100644
index 0000000..8ebfbe3
--- /dev/null
+++ b/protocols/netconf/api/src/main/java/org/onosproject/netconf/NetconfProxyMessage.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * 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.netconf;
+
+import org.onosproject.net.DeviceId;
+
+import java.util.List;
+
+/**
+ * Interface representing a NETCONF proxy message.
+ */
+public interface NetconfProxyMessage {
+
+    enum SubjectType {
+        RPC,
+        // FIXME in the final form there should only be (async) RPC
+        // and REQUEST, REQUEST_SYNC should go away
+        // once NetconfSession methods got cleaned up.
+        REQUEST,
+        REQUEST_SYNC,
+        START_SUBSCRIPTION,
+        END_SUBSCRIPTION,
+        GET_SESSION_ID,
+        GET_DEVICE_CAPABILITIES_SET,
+        SET_ONOS_CAPABILITIES
+    }
+
+    /**
+     * Returns the subject of the message.
+     *
+     * @return subject in enum subject type
+     */
+    NetconfProxyMessage.SubjectType subjectType();
+
+    /**
+     * Returns the device id of the device to which the message is intended.
+     * @return device id
+     */
+    DeviceId deviceId();
+
+    /**
+     * Returns the arguments of the intended method call in order.
+     * @return arguments
+     */
+    List<String> arguments();
+}