YMS broker and Notification handler

Change-Id: Ic3659b2c2ad26ea2db1f03725b4883f19db2cc41
diff --git a/apps/yms/api/src/main/java/org/onosproject/yms/ysr/YangModuleInformation.java b/apps/yms/api/src/main/java/org/onosproject/yms/ysr/YangModuleInformation.java
new file mode 100644
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+++ b/apps/yms/api/src/main/java/org/onosproject/yms/ysr/YangModuleInformation.java
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+/*
+ * 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.ysr;
+
+import java.util.List;
+
+/**
+ * Abstraction of an entity which provides YANG module information.
+ *
+ * Reference RFC 7895
+ * The following information is needed by a client application (for each
+ * YANG module in the library) to fully utilize the YANG data modeling
+ * language:
+ *
+ * o  name: The name of the YANG module.
+ *
+ * o  revision: Each YANG module and submodule within the library has a
+ * revision.  This is derived from the most recent revision statement
+ * within the module or submodule.  If no such revision statement
+ * exists, the module's or submodule's revision is the zero-length
+ * string.
+ *
+ * o  submodule list: The name and revision of each submodule used by
+ * the module MUST be identified.
+ *
+ * o  feature list: The name of each YANG feature supported by the
+ * server MUST be identified.
+ *
+ * o  deviation list: The name of each YANG module used for deviation
+ * statements MUST be identified.
+ */
+public interface YangModuleInformation {
+    /**
+     * Retrieves the YANG modules identifier.
+     *
+     * @return YANG modules identifier
+     */
+    YangModuleIdentifier getModuleIdentifier();
+
+    /**
+     * Retrieves the YANG modules namespace.
+     * The XML namespace identifier for this module.
+     *
+     * @return YANG modules namespace
+     */
+    String getNamespace();
+
+    /**
+     * Reference RFC 7895
+     * Retrieves the list of YANG feature names from this module that are
+     * supported by the server, regardless of whether they are
+     * defined in the module or any included submodule.
+     *
+     * @return list of YANG features
+     */
+    List<String> getFeatureList();
+
+    /**
+     * Retrieves the list of submodules in the module.
+     * The name and revision of each submodule used by
+     * the module MUST be identified.
+     *
+     * Each entry represents one submodule within the
+     * parent module.
+     *
+     * @return list of submodules in the module
+     */
+    List<YangModuleIdentifier> getSubModuleIdentifier();
+}