GOSSIP-13 Add two way protocol

src/main/java/org/apache/gossip/manager/UdpUtil.java

@@ -0,0 +1,28 @@
+package org.apache.gossip.manager;
+
+import java.nio.ByteBuffer;
+
+public class UdpUtil {
+
+  public static int readPacketLengthFromBuffer(byte [] buffer){
+    int packetLength = 0;
+    for (int i = 0; i < 4; i++) {
+      int shift = (4 - 1 - i) * 8;
+      packetLength += (buffer[i] & 0x000000FF) << shift;
+    }
+    return packetLength;
+  }
+  
+  public static byte[] createBuffer(int packetLength, byte[] jsonBytes) {
+    byte[] lengthBytes = new byte[4];
+    lengthBytes[0] = (byte) (packetLength >> 24);
+    lengthBytes[1] = (byte) ((packetLength << 8) >> 24);
+    lengthBytes[2] = (byte) ((packetLength << 16) >> 24);
+    lengthBytes[3] = (byte) ((packetLength << 24) >> 24);
+    ByteBuffer byteBuffer = ByteBuffer.allocate(4 + jsonBytes.length);
+    byteBuffer.put(lengthBytes);
+    byteBuffer.put(jsonBytes);
+    byte[] buf = byteBuffer.array();
+    return buf;
+  }
+}