diff --git a/nsync/src/sync-socket.cc b/nsync/src/sync-socket.cc
new file mode 100644
index 0000000..db51ce2
--- /dev/null
+++ b/nsync/src/sync-socket.cc
@@ -0,0 +1,155 @@
+/* -*- Mode: C32++; 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: Yingdi Yu <yingdi@cs.ucla.edu>
+ */
+
+#include "sync-socket.h"
+#include "sync-logging.h"
+
+using namespace std;
+using namespace ndn;
+
+INIT_LOGGER ("SyncSocket");
+
+namespace Sync {
+
+using ndn::shared_ptr;
+
+SyncSocket::SyncSocket (const Name &syncPrefix, 
+                        shared_ptr<Validator> validator,
+                        shared_ptr<Face> face,
+                        NewDataCallback dataCallback, 
+                        RemoveCallback rmCallback )
+  : m_newDataCallback(dataCallback)
+  , m_validator(validator)
+  , m_keyChain(new KeyChain())
+  , m_face(face)
+  , m_ioService(face->ioService())
+  , m_syncLogic (syncPrefix,
+                 validator,
+                 face,
+                 bind(&SyncSocket::passCallback, this, _1),
+                 rmCallback)
+{}
+
+SyncSocket::~SyncSocket()
+{
+}
+
+bool 
+SyncSocket::publishData(const Name &prefix, uint64_t session, const char *buf, size_t len, int freshness,uint64_t seq)
+{
+  shared_ptr<Data> data = make_shared<Data>();
+  data->setContent(reinterpret_cast<const uint8_t*>(buf), len);
+  data->setFreshnessPeriod(1000*freshness);
+
+  m_ioService->post(bind(&SyncSocket::publishDataInternal, this, data, prefix, session,seq));
+
+  return true;  
+}
+
+void
+SyncSocket::publishDataInternal(shared_ptr<Data> data, const Name &prefix, uint64_t session,uint64_t seq)
+{
+  uint64_t sequence = seq;
+  Name dataName = prefix;
+  dataName.append(boost::lexical_cast<string>(session)).append(boost::lexical_cast<string>(sequence));
+  data->setName(dataName);
+
+  m_keyChain->sign(*data);  
+  m_face->put(*data);
+
+  SeqNo s(session, sequence + 1);
+
+  m_sequenceLog[prefix] = s;
+  m_syncLogic.addLocalNames (prefix, session, sequence);
+}
+
+void 
+SyncSocket::fetchData(const Name &prefix, const SeqNo &seq, const OnDataValidated& onValidated, int retry)
+{
+  Name interestName = prefix;
+  interestName.append(boost::lexical_cast<string>(seq.getSession())).append(boost::lexical_cast<string>(seq.getSeq()));
+
+  const OnDataValidationFailed& onValidationFailed = bind(&SyncSocket::onDataValidationFailed, this, _1);
+  
+  ndn::Interest interest(interestName);
+  interest.setMustBeFresh(true);
+  m_face->expressInterest(interest, 
+                          bind(&SyncSocket::onData, this, _1, _2, onValidated, onValidationFailed), 
+                          bind(&SyncSocket::onDataTimeout, this, _1, retry, onValidated, onValidationFailed));
+
+}
+
+void
+SyncSocket::onData(const ndn::Interest& interest, Data& data,
+                   const OnDataValidated& onValidated,
+                   const OnDataValidationFailed& onValidationFailed)
+{
+  m_validator->validate(data, onValidated, onValidationFailed);
+}
+
+void
+SyncSocket::onDataTimeout(const ndn::Interest& interest, 
+                          int retry,
+                          const OnDataValidated& onValidated,
+                          const OnDataValidationFailed& onValidationFailed)
+{
+  if(retry > 0)
+    {
+      m_face->expressInterest(interest,
+                              bind(&SyncSocket::onData,
+                                   this,
+                                   _1,
+                                   _2,
+                                   onValidated,
+                                   onValidationFailed),
+                              bind(&SyncSocket::onDataTimeout, 
+                                   this,
+                                   _1,
+                                   retry - 1,
+                                   onValidated,
+                                   onValidationFailed));
+                              
+    }
+  else
+    _LOG_DEBUG("interest eventually time out!");
+}
+
+void
+SyncSocket::onDataValidationFailed(const shared_ptr<const Data>& data)
+{
+  _LOG_DEBUG("data cannot be verified!");
+}
+
+
+uint64_t
+SyncSocket::getNextSeq (const Name &prefix, uint64_t session)
+{
+  SequenceLog::iterator i = m_sequenceLog.find (prefix);
+
+  if (i != m_sequenceLog.end ())
+    {
+      SeqNo s = i->second;
+      if (s.getSession() == session)
+        return s.getSeq();
+    }
+  return 0;
+}
+
+}//Sync