diff --git a/src/sync-core.h b/src/sync-core.h
index 7e787d3..b06b8b8 100644
--- a/src/sync-core.h
+++ b/src/sync-core.h
@@ -25,6 +25,8 @@
 #include "sync-log.h"
 #include <ccnx-wrapper.h>
 #include <event-scheduler.h>
+#include <boost/function.hpp>
+#include <boost/thread/shared_mutex.hpp>
 
 using namespace std;
 using namespace Ccnx;
@@ -32,13 +34,71 @@
 class SyncCore
 {
 public:
-  SyncCore(const string &path, const Name &localName, CcnxWrapperPtr handle, SchedulerPtr scheduler);
+  typedef boost::function<void (const SyncStateMsgPtr & stateMsg) > StateMsgCallback;
+  typedef sqlite3_int64 seqno_t;
+  typedef Map<Name, Name> YellowPage;
+  typedef boost::shared_mutex Mutex;
+  typedef boost::shared_lock<Mutex> ReadLock;
+  typedef boost::unique_lock<Mutex> WriteLock;
+
+  static const int FRESHNESS = 2;
+
+public:
+  SyncCore(const string &path                   // path where SyncLog is stored
+           , const Name &userName               // unique permanent name for local user
+           , const Name &localPrefix            // routable name used by the local user
+           , const Name &syncPrefix             // the prefix for the sync collection
+           , const StateMsgCallback &callback   // callback when state change is detected
+           , CcnxWrapperPtr handle
+           , SchedulerPtr scheduler);
   ~SyncCore();
 
+  // some other code should call this fuction when local prefix
+  // changes; e.g. when wake up in another network
+  void
+  updateLocalPrefix(const Name &localPrefix);
+
+  void
+  updateLocalState(seqno_t);
+
+  Name
+  yp(const Name &name);
+
+  void
+  handleSyncInterest(const Name &name);
+
+  Closure::TimeoutCallbackReturnValue
+  handleSyncInterestTimeout(const Name &name);
+
+  void
+  handleSyncData(const Name &name, const Bytes &content);
+
+  void
+  deregister();
+
+protected:
+  void
+  sendSyncInterest();
+
+  Name
+  constructSyncName(const HashPtr &hash);
+
+  static void
+  msgToBytes(const SyncStateMsgPtr &msg, Bytes &bytes);
+
 protected:
   SyncLog m_log;
-  CcnxWrapperPtr m_handle;
   SchedulerPtr m_scheduler;
+  StateMsgCallback m_stateMsgCallback;
+  Name m_userName;
+  Name m_localPrefix;
+  Name m_syncPrefix;
+  HashPtr m_rootHash;
+  YellowPage m_yp;
+  Mutex m_ypMutex;
+  CcnxWrapperPtr m_handle;
+  Closure *m_interestClosure;
+
 };
 
 #endif // SYNC_CORE_H