[ONOS-2447]RFC7047's API and its implementation and five main tables.
provide RFC7047's API and its implementation, and five main table which
contain Bridge, Controller, Interface, Open_vSwitch and Port 

Change-Id: I9e995a056fd55c986f5866c85ac712f1792cff4f
diff --git a/ovsdb/rfc/src/main/java/org/onosproject/ovsdb/rfc/utils/VersionUtil.java b/ovsdb/rfc/src/main/java/org/onosproject/ovsdb/rfc/utils/VersionUtil.java
new file mode 100644
index 0000000..9c5e970
--- /dev/null
+++ b/ovsdb/rfc/src/main/java/org/onosproject/ovsdb/rfc/utils/VersionUtil.java
@@ -0,0 +1,57 @@
+/*
+ * 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.ovsdb.rfc.utils;
+
+/**
+ * Version utility class.
+ */
+public final class VersionUtil {
+
+    /**
+     * Constructs a VersionUtil object. Utility classes should not have a public
+     * or default constructor, otherwise IDE will compile unsuccessfully. This
+     * class should not be instantiated.
+     */
+    private VersionUtil() {
+    }
+
+    public static final String DEFAULT_VERSION_STRING = "0.0.0";
+    private static final String FORMAT = "(\\d+)\\.(\\d+)\\.(\\d+)";
+
+    /**
+     * Match version by the format.
+     * @param version the version String
+     * @throws IllegalArgumentException this is an illegal argument exception
+     */
+    public static void versionMatch(String version) {
+        if (!version.matches(FORMAT)) {
+            throw new IllegalArgumentException("<" + version
+                    + "> does not match format " + FORMAT);
+        }
+    }
+
+    /**
+     * Compare fromVersion and toVersion.
+     * @param fromVersion the initial version
+     * @param toVersion the end of the version
+     * @return a long number
+     */
+    public static long versionCompare(String fromVersion, String toVersion) {
+        Long fromNum = Long.parseLong(fromVersion.replace(".", ""));
+        Long toNum = Long.parseLong(toVersion.replace(".", ""));
+        return (fromNum - toNum);
+    }
+}