diff --git a/model/sync-app-data-fetch.h b/model/sync-app-data-fetch.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_LEAF_H
+#define SYNC_LEAF_H
+#include "sync-ccnx-wrapper.h"
+#include <boost/function.hpp>
+#include <boost/shared_ptr.hpp>
+
+namespace Sync {
+
+/**
+ * \ingroup sync
+ * @brief fetch application data, by default it will try to fetch every piece
+ * of data
+ */
+class AppDataFetch
+{
+public:
+	AppDataFetch(boost::function<void (boost::shared_ptr<DataBuffer>)>
+	dataCallback);
+	void setDataCallback(boost::function<void (boost::shared_ptr<DataBuffer>)>
+	dataCallback) {m_dataCallback = dataCallback;}
+	void fetch(string prefix, long startSeq, long endSeq);
+
+private:
+	boost::shared_ptr<CcnxWrapper> ccnxHandle;
+	boost::shared_ptr<boost::function<void (boost::shared_ptr<DataBuffer>)>
+	m_dataCallback;
+};
+
+
+} // Sync
+
+#endif // SYNC_LEAF_H