[ONOS-4694] YANG management system outline and YMSM/YDT interfaces

Change-Id: I050ed98ba18edc2c2cea2abafeee6d8c9061b579
diff --git a/apps/yms/api/src/main/java/org/onosproject/yms/ydt/YmsOperationExecutionStatus.java b/apps/yms/api/src/main/java/org/onosproject/yms/ydt/YmsOperationExecutionStatus.java
new file mode 100644
index 0000000..3ac63ee
--- /dev/null
+++ b/apps/yms/api/src/main/java/org/onosproject/yms/ydt/YmsOperationExecutionStatus.java
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2016-present 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.yms.ydt;
+
+/**
+ * Abstraction of an entity which represents YANG management system operation
+ * result. Once the protocol translates the request information into a abstract
+ * YANG data tree, it uses YANG management system as a broker to get the
+ * operation executed in ONOS. Protocols uses a request Yang management
+ * system to delegate the operation request.
+ *
+ * YANG management system is responsible to split the protocol operation
+ * across application(s) which needs to participate, and collate the
+ * response(s) from application(s) and return an effective result of the
+ * operation request. The result of the operation request is returned in
+ * YMS operation result.
+ */
+public interface YmsOperationExecutionStatus {
+    // TODO
+}