diff --git a/model/sync-data-buffer.h b/model/sync-data-buffer.h
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+/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2012 University of California, Los Angeles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Author: Zhenkai Zhu <zhenkai@cs.ucla.edu>
+ *         卞超轶 Chaoyi Bian <bcy@pku.edu.cn>
+ *	   Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+ */
+
+#ifndef SYNC_STATE_H
+#define SYNC_STATE_H
+
+#include <tinyxml.h>
+#include <boost/shared_ptr.hpp>
+#include "sync-diff-state.h"
+#include "sync-full-state.h"
+
+
+/**
+ * \defgroup sync SYNC protocol
+ *
+ * Implementation of SYNC protocol
+ */
+namespace Sync {
+
+/**
+ * \ingroup sync
+ * @brief handles conversion from xml encoded data ("wire_format") to states
+ * data (FullState or DiffState)
+ */
+/**
+ * \ingroup sync
+ * @brief Data wrapper with size; convert from/to FullState and DiffState
+ */
+class DataBuffer {
+private:
+	unsigned char *m_buffer;
+	size_t m_len;
+public:
+	DataBuffer() {m_buffer = NULL; m_len = 0;}
+	DataBuffer(const unsigned char *buffer, size_t len);
+	DataBuffer(const DataBuffer &dataBuffer);
+	DataBuffer &operator=(const DataBuffer &dataBuffer);
+	~DataBuffer();	
+	size_t length() {return len;}
+	const unsigned char *buffer() { return const_cast<const unsigned char *> (buffer); }
+
+	DataBuffer &operator<<(FullState &fs);
+	DataBuffer &operator<<(DiffState &ds);
+
+	FullState &operator>>(FullState &fs);
+	DiffState &operator>>(DiffState &ds);
+};
+
+
+
+
+} // Sync
+
+#endif // SYNC_STATE_H