diff --git a/model/sync-app-data-fetch.cc b/model/sync-app-data-fetch.cc
index 43e089b..4cf22a3 100644
--- a/model/sync-app-data-fetch.cc
+++ b/model/sync-app-data-fetch.cc
@@ -29,16 +29,32 @@
 {
 
 void
-AppDataFetch::fetch (const string &prefix, uint32_t startSeq, uint32_t endSeq)
+AppDataFetch::onUpdate (const std::string &prefix, const SeqNo &newSeq, const SeqNo &oldSeq)
 {
-  for (uint32_t i = startSeq; i <= endSeq; i++)
-  {
-    if (i == 0)
-      continue;
-    ostringstream interestName;
-    interestName << prefix << "/" << i;
-    m_ccnxHandle->sendInterest (interestName.str (), m_dataCallback);
-  }
+  // sequence number logic here
+  uint32_t start = 0;
+  if (oldSeq.isValid ())
+    {
+      start = oldSeq.getSeq () + 1;
+    }
+  uint32_t end = newSeq.getSeq ();
+
+  //
+  // add logic for wrap around
+  //
+
+  for (uint32_t i = start; i <= end; i++)
+    {
+      ostringstream interestName;
+      interestName << prefix << "/" << newSeq.getSession () << "/" << i;
+      m_ccnxHandle->sendInterest (interestName.str (), m_dataCallback);
+    }
+}
+
+void
+AppDataFetch::onRemove (const std::string &prefix)
+{
+  // I guess this should be somewhere in app
 }
 
 }
diff --git a/model/sync-app-data-fetch.h b/model/sync-app-data-fetch.h
index 3f368cb..1037807 100644
--- a/model/sync-app-data-fetch.h
+++ b/model/sync-app-data-fetch.h
@@ -24,6 +24,7 @@
 #define SYNC_APP_DATA_FETCH_H
 
 #include "sync-ccnx-wrapper.h"
+#include "sync-seq-no.h"
 
 namespace Sync {
 
@@ -57,15 +58,23 @@
   }
 
   /**
-   * @brief Fetch data for a certain name prefix
+   * @brief Fired from SyncLogic when new data is available
    *
    * @param prefix the prefix for the data
-   * @param startSeq the start of sequence number range (inclusive)
-   * @param endSeq the end of sequence number range (inclusive)
+   * @param newSeq old session ID/sequence number
+   * @param oldSeq new session ID/sequence number
    */
   void
-  fetch (const std::string &prefix, uint32_t startSeq, uint32_t endSeq);
+  onUpdate (const std::string &prefix, const SeqNo &newSeq, const SeqNo &oldSeq);
 
+  /**
+   * @brief Fired from SyncLogic when data is removed
+   *
+   * @param prefix the prefix for the data
+   */
+  void
+  onRemove (const std::string &prefix);
+  
 private:
   CcnxWrapperPtr m_ccnxHandle;
   CcnxWrapper::DataCallback m_dataCallback;
diff --git a/model/sync-app-data-publish.cc b/model/sync-app-data-publish.cc
index 66ca1ae..17d52ee 100644
--- a/model/sync-app-data-publish.cc
+++ b/model/sync-app-data-publish.cc
@@ -31,10 +31,10 @@
 string
 AppDataPublish::getRecentData (const string &prefix, uint32_t session)
 {
-	if (m_recentData.find(make_pair(prefix, session)) != m_recentData.end())
-		return m_recentData[make_pair(prefix, session)];
-	else
-		return "";
+  if (m_recentData.find(make_pair(prefix, session)) != m_recentData.end())
+    return m_recentData[make_pair(prefix, session)];
+  else
+    return "";
 }
 
 uint32_t
@@ -68,14 +68,14 @@
   m_sequenceLog[name] = s;
 
   ostringstream contentNameWithSeqno;
-  contentNameWithSeqno << name << "/" << seq;
+  contentNameWithSeqno << name << "/" << session << "/" << seq;
 
   m_ccnxHandle->publishData (contentNameWithSeqno.str (), dataBuffer, freshness);
 
   unordered_map<pair<string, uint32_t>, string>::iterator it = m_recentData.find(make_pair(name, session));
-	if (it != m_recentData.end()) 
-		m_recentData.erase(it);
-	m_recentData.insert(make_pair(make_pair(name, session), dataBuffer));
+  if (it != m_recentData.end()) 
+    m_recentData.erase(it);
+  m_recentData.insert(make_pair(make_pair(name, session), dataBuffer));
 
   return true;
 }
diff --git a/model/sync-app-socket.cc b/model/sync-app-socket.cc
index d703e76..3dca250 100644
--- a/model/sync-app-socket.cc
+++ b/model/sync-app-socket.cc
@@ -33,7 +33,8 @@
   , m_fetcher (m_ccnxHandle, dataCallback)
   , m_publisher (m_ccnxHandle)
   , m_syncLogic (syncPrefix,
-                 bind (&AppDataFetch::fetch, m_fetcher, _1, _2, _3),
+                 bind (&AppDataFetch::onUpdate, m_fetcher, _1, _2, _3),
+                 bind (&AppDataFetch::onRemove, m_fetcher, _1),
                  m_ccnxHandle)
 {
 }
diff --git a/model/sync-diff-leaf.h b/model/sync-diff-leaf.h
index 1e3143a..c4aab82 100644
--- a/model/sync-diff-leaf.h
+++ b/model/sync-diff-leaf.h
@@ -74,6 +74,7 @@
 };
 
 typedef boost::shared_ptr<DiffLeaf> DiffLeafPtr;
+typedef boost::shared_ptr<const DiffLeaf> DiffLeafConstPtr;
 
 std::ostream &
 operator << (std::ostream &os, Operation op);
diff --git a/model/sync-diff-state.cc b/model/sync-diff-state.cc
index 65323d3..1c6a41c 100644
--- a/model/sync-diff-state.cc
+++ b/model/sync-diff-state.cc
@@ -43,7 +43,7 @@
 DiffState::diff () const
 {
   DiffStatePtr ret = make_shared<DiffState> ();
-
+  
   DiffStatePtr state = m_next;
   while (state != 0)
     {
@@ -57,11 +57,26 @@
 DiffState &
 DiffState::operator += (const DiffState &state)
 {
+  BOOST_FOREACH (LeafConstPtr _leaf, state.getLeaves ())
+    {
+      DiffLeafConstPtr leaf = dynamic_pointer_cast<const DiffLeaf> (_leaf);
+      BOOST_ASSERT (leaf != 0);
+
+      if (leaf->getOperation () == UPDATE)
+        update (leaf->getInfo (), leaf->getSeq ());
+      else if (leaf->getOperation () == REMOVE)
+        remove (leaf->getInfo ());
+      else
+        {
+          BOOST_ASSERT (false);
+        }
+    }
+  
   return *this;
 }
   
 // from State
-bool
+boost::tuple<bool/*inserted*/, bool/*updated*/, SeqNo/*oldSeqNo*/>
 DiffState::update (NameInfoConstPtr info, const SeqNo &seq)
 {
   m_leaves.erase (info);
@@ -69,7 +84,7 @@
   DiffLeafPtr leaf = make_shared<DiffLeaf> (info, cref (seq));
   m_leaves.insert (leaf);
 
-  return true;
+  return make_tuple (true, false, SeqNo ());
 }
 
 bool
diff --git a/model/sync-diff-state.h b/model/sync-diff-state.h
index 6a43aef..aed6b32 100644
--- a/model/sync-diff-state.h
+++ b/model/sync-diff-state.h
@@ -86,7 +86,7 @@
   operator += (const DiffState &state);
   
   // from State
-  virtual bool
+  virtual boost::tuple<bool/*inserted*/, bool/*updated*/, SeqNo/*oldSeqNo*/>
   update (NameInfoConstPtr info, const SeqNo &seq);
 
   virtual bool
diff --git a/model/sync-full-state.cc b/model/sync-full-state.cc
index ed3a3ee..748e408 100644
--- a/model/sync-full-state.cc
+++ b/model/sync-full-state.cc
@@ -81,7 +81,7 @@
 }
 
 // from State
-bool
+boost::tuple<bool/*inserted*/, bool/*updated*/, SeqNo/*oldSeqNo*/>
 FullState::update (NameInfoConstPtr info, const SeqNo &seq)
 {
 #ifndef STANDALONE  
@@ -96,16 +96,20 @@
   if (item == m_leaves.end ())
     {
       m_leaves.insert (make_shared<FullLeaf> (info, cref (seq)));
+      return make_tuple (true, false, SeqNo ());
     }
   else
     {
       if ((*item)->getSeq () == seq || seq < (*item)->getSeq ())
-        return false;
-      
+        {
+          return make_tuple (false, false, SeqNo ());
+        }
+
+      SeqNo old = (*item)->getSeq ();
       m_leaves.modify (item,
                        ll::bind (&Leaf::setSeq, *ll::_1, seq));
+      return make_tuple (false, true, old);
     }
-  return true;
 }
 
 bool
@@ -122,7 +126,7 @@
   LeafContainer::iterator item = m_leaves.find (info);
   if (item != m_leaves.end ())
     {
-      m_leaves.erase (info);
+      m_leaves.erase (item);
       return true;
     }
   else
diff --git a/model/sync-full-state.h b/model/sync-full-state.h
index 2aac7b9..5b80aff 100644
--- a/model/sync-full-state.h
+++ b/model/sync-full-state.h
@@ -67,7 +67,7 @@
   getDigest ();
   
   // from State
-  virtual bool
+  virtual boost::tuple<bool/*inserted*/, bool/*updated*/, SeqNo/*oldSeqNo*/>
   update (NameInfoConstPtr info, const SeqNo &seq);
 
   virtual bool
diff --git a/model/sync-logic.cc b/model/sync-logic.cc
index f7bf4e7..e39b86b 100644
--- a/model/sync-logic.cc
+++ b/model/sync-logic.cc
@@ -38,11 +38,13 @@
 const boost::posix_time::time_duration SyncLogic::m_delayedCheckTime = boost::posix_time::seconds (4.0);
 
 
-SyncLogic::SyncLogic (const string &syncPrefix,
-                      LogicCallback fetchCallback,
+SyncLogic::SyncLogic (const std::string &syncPrefix,
+                      LogicUpdateCallback onUpdate,
+                      LogicRemoveCallback onRemove,
                       CcnxWrapperPtr ccnxHandle)
   : m_syncPrefix (syncPrefix)
-  , m_fetchCallback (fetchCallback)
+  , m_onUpdate (onUpdate)
+  , m_onRemove (onRemove)
   , m_ccnxHandle (ccnxHandle)
   , m_delayedCheckThreadRunning (true)
 {
@@ -128,6 +130,7 @@
 SyncLogic::processSyncInterest (DigestConstPtr digest, const std::string &interestName, bool timedProcessing/*=false*/)
 {
   // cout << "SyncLogic::processSyncInterest " << timedProcessing << endl;
+  recursive_mutex::scoped_lock lock (m_stateMutex);
     
   if (*m_state.getDigest() == *digest)
   {
@@ -172,132 +175,101 @@
 void
 SyncLogic::processSyncData (const string &name, const string &dataBuffer)
 {
-  string last = name.substr(name.find_last_of("/") + 1);
-  istringstream ss (dataBuffer);
-
-  DiffStatePtr diffLog = make_shared<DiffState>();
-
-  if (last == "state")
-  {
-    FullState full;
-    ss >> full;
-    BOOST_FOREACH (LeafConstPtr leaf, full.getLeaves().get<ordered>())
-    {
-      NameInfoConstPtr info = leaf->getInfo ();
-      LeafContainer::iterator it = m_state.getLeaves().find (info);
-
-      SeqNo seq = leaf->getSeq ();
-
-      // if (it == m_state.getLeaves().end())
-      // {
-      //   string prefix = info.toString();
-      //   prefix += "/";
-      //   prefix += seq.getSession();
-      //   m_fetchCallback (prefix, 1, seq.getSeq());
-      //   m_state.update(pInfo, seq);
-      //   diffLog->update(pInfo, seq);
-      // }
-      // else
-      // {
-      //   SeqNo currSeq = (*it)->getSeq();
-      //   if (currSeq < seq)
-      //   {
-      //     string prefix = info.toString();
-      //     prefix += "/";
-      //     prefix += seq.getSession();
-
-      //     if (currSeq.getSession() == seq.getSession())
-      //       m_fetchCallback(prefix, currSeq.getSeq() + 1, seq.getSeq());
-      //     else
-      //       m_fetchCallback(prefix, 1, seq.getSeq());
-
-      //     m_state.update(pInfo, seq);
-      //     diffLog->update(pInfo, seq);
-      //   }
-      // }
-    }
-  }
-  else
-  {
-    DiffState diff;
-    ss >> diff;
-    BOOST_FOREACH (LeafConstPtr leaf, diff.getLeaves().get<ordered>())
-    {
-      shared_ptr<const DiffLeaf> diffLeaf = dynamic_pointer_cast<const DiffLeaf> (leaf);
-      if (diffLeaf == 0)
-        {
-          return;
-          /// \todo Log the error
-        }
-      NameInfoConstPtr info = diffLeaf->getInfo();
-      LeafContainer::iterator it = m_state.getLeaves().find (info);
-      SeqNo seq = diffLeaf->getSeq();
-
-      // switch (diffLeaf->getOperation())
-      // {
-      //   case UPDATE:
-      //     if (it == m_state.getLeaves().end())
-      //     {
-      //       string prefix = info.toString();
-      //       prefix += "/";
-      //       prefix += seq.getSession();
-      //       m_fetchCallback(prefix, 1, seq.getSeq());
-
-      //       NameInfoConstPtr pInfo = StdNameInfo::FindOrCreate(info.toString());
-      //       m_state.update(pInfo, seq);
-      //       diffLog->update(pInfo, seq);
-      //     }
-      //     else
-      //     {
-      //       SeqNo currSeq = (*it)->getSeq();
-      //       if (currSeq < seq)
-      //       {
-      //         string prefix = info.toString();
-      //         prefix += "/";
-      //         prefix += seq.getSession();
-
-      //         if (currSeq.getSession() == seq.getSession())
-      //           m_fetchCallback(prefix, currSeq.getSeq() + 1, seq.getSeq());
-      //         else
-      //           m_fetchCallback(prefix, 1, seq.getSeq());
-
-      //         NameInfoConstPtr pInfo = StdNameInfo::FindOrCreate(info.toString());
-      //         m_state.update(pInfo, seq);
-      //         diffLog->update(pInfo, seq);
-      //       }
-      //     }
-      //     break;
-
-      //   case REMOVE:
-      //     if (it != m_state.getLeaves().end())
-      //     {
-      //       NameInfoConstPtr pInfo = StdNameInfo::FindOrCreate(info.toString());
-      //       m_state.remove(pInfo);
-      //       diffLog->remove(pInfo);
-      //     }
-      //     break;
-
-      //   default:
-      //     break;
-      // }
-    }
-  }
-
-  diffLog->setDigest(m_state.getDigest());
-  m_log.insert (diffLog);
-
-  // notify upper layer
-  BOOST_FOREACH (LeafConstPtr leaf, diffLog->getLeaves ())
-    {
-    }
+  DiffStatePtr diffLog = make_shared<DiffState> ();
   
-  sendSyncInterest();
+  try
+    {
+      recursive_mutex::scoped_lock lock (m_stateMutex);
+      
+      string last = name.substr(name.find_last_of("/") + 1);
+      istringstream ss (dataBuffer);
+
+      if (last == "state")
+        {
+          FullState full;
+          ss >> full;
+          BOOST_FOREACH (LeafConstPtr leaf, full.getLeaves()) // order doesn't matter
+            {
+              NameInfoConstPtr info = leaf->getInfo ();
+              SeqNo seq = leaf->getSeq ();
+
+              bool inserted = false;
+              bool updated = false;
+              SeqNo oldSeq;
+              tie (inserted, updated, oldSeq) = m_state.update (info, seq);
+
+              if (updated)
+                {
+                  diffLog->update (info, seq);
+                  m_onUpdate (info->toString (), seq.getSeq(), oldSeq);
+                }
+            }
+        }
+      else
+        {
+          DiffState diff;
+          ss >> diff;
+          BOOST_FOREACH (LeafConstPtr leaf, diff.getLeaves().get<ordered>())
+            {
+              DiffLeafConstPtr diffLeaf = dynamic_pointer_cast<const DiffLeaf> (leaf);
+              BOOST_ASSERT (diffLeaf != 0);
+
+              NameInfoConstPtr info = diffLeaf->getInfo();
+              if (diffLeaf->getOperation() == UPDATE)
+                {
+                  SeqNo seq = diffLeaf->getSeq();
+
+                  bool inserted = false;
+                  bool updated = false;
+                  SeqNo oldSeq;
+                  tie (inserted, updated, oldSeq) = m_state.update (info, seq);
+
+                  if (updated)
+                    {
+                      diffLog->update (info, seq);
+                      m_onUpdate (info->toString (), seq.getSeq(), oldSeq);
+                    }
+                }
+              else if (diffLeaf->getOperation() == REMOVE)
+                {
+                  if (m_state.remove (info))
+                    {
+                      diffLog->remove (info);
+                      m_onRemove (info->toString ());
+                    }
+                }
+              else
+                {
+                  BOOST_ASSERT (false); // just in case
+                }
+            }
+        }
+
+      diffLog->setDigest(m_state.getDigest());
+      if (m_log.size () > 0)
+        {
+          m_log.get<sequenced> ().front ()->setNext (diffLog);
+        }
+      m_log.insert (diffLog);
+    }
+  catch (Error::SyncXmlDecodingFailure &e)
+    {
+      // log error
+      return;
+    }
+
+  if (diffLog->getLeaves ().size () > 0)
+    {
+      sendSyncInterest();
+    }
 }
 
 void
-SyncLogic::processPendingSyncInterests(DiffStatePtr &diff) {
+SyncLogic::processPendingSyncInterests(DiffStatePtr &diff) 
+{
+  recursive_mutex::scoped_lock lock (m_stateMutex);
   diff->setDigest(m_state.getDigest());
-	m_log.insert(diff);
+  m_log.insert(diff);
 
   vector<string> pis = m_syncInterestTable.fetchAll ();
   stringstream ss;
@@ -311,6 +283,7 @@
 void
 SyncLogic::addLocalNames (const string &prefix, uint32_t session, uint32_t seq)
 {
+  recursive_mutex::scoped_lock lock (m_stateMutex);
   NameInfoConstPtr info = StdNameInfo::FindOrCreate(prefix);
   SeqNo seqN(session, seq);
   m_state.update(info, seqN);
@@ -318,23 +291,27 @@
   DiffStatePtr diff = make_shared<DiffState>();
   diff->update(info, seqN);
 
-	processPendingSyncInterests(diff);
+  processPendingSyncInterests(diff);
 }
 
 void
-SyncLogic::remove(const string &prefix) {
+SyncLogic::remove(const string &prefix) 
+{
+  recursive_mutex::scoped_lock lock (m_stateMutex);
   NameInfoConstPtr info = StdNameInfo::FindOrCreate(prefix);
-	m_state.remove(info);	
+  m_state.remove(info);	
 
   DiffStatePtr diff = make_shared<DiffState>();
-	diff->remove(info);
+  diff->remove(info);
 
-	processPendingSyncInterests(diff);
+  processPendingSyncInterests(diff);
 }
 
 void
 SyncLogic::sendSyncInterest ()
 {
+  recursive_mutex::scoped_lock lock (m_stateMutex);
+
   ostringstream os;
   os << m_syncPrefix << "/" << m_state.getDigest();
 
diff --git a/model/sync-logic.h b/model/sync-logic.h
index 50c995f..6c112dd 100644
--- a/model/sync-logic.h
+++ b/model/sync-logic.h
@@ -25,6 +25,7 @@
 #include <boost/shared_ptr.hpp>
 #include <boost/function.hpp>
 #include "boost/date_time/posix_time/posix_time_types.hpp"
+#include <boost/thread/recursive_mutex.hpp>
 
 #include "sync-ccnx-wrapper.h"
 #include "sync-interest-table.h"
@@ -44,7 +45,8 @@
 class SyncLogic
 {
 public:
-  typedef boost::function<void (const std::string &, uint32_t, uint32_t)> LogicCallback;
+  typedef boost::function< void ( const std::string &/*prefix*/, const SeqNo &/*newSeq*/, const SeqNo &/*oldSeq*/ ) > LogicUpdateCallback;
+  typedef boost::function< void ( const std::string &/*prefix*/ ) > LogicRemoveCallback;
 
   /**
    * @brief Constructor
@@ -53,7 +55,10 @@
    * @param ccnxHandle ccnx handle
    * the app data when new remote names are learned
    */
-  SyncLogic (const std::string &syncPrefix, LogicCallback fetch, CcnxWrapperPtr ccnxHandle);
+  SyncLogic (const std::string &syncPrefix,
+             LogicUpdateCallback onUpdate,
+             LogicRemoveCallback onRemove,
+             CcnxWrapperPtr ccnxHandle);
 
   ~SyncLogic ();
 
@@ -106,10 +111,13 @@
 
   FullState m_state;
   DiffStateContainer m_log;
+  boost::recursive_mutex m_stateMutex;
+
   SyncInterestTable m_syncInterestTable;
 
   std::string m_syncPrefix;
-  LogicCallback m_fetchCallback;
+  LogicUpdateCallback m_onUpdate;
+  LogicRemoveCallback m_onRemove;
   CcnxWrapperPtr m_ccnxHandle;
 
   boost::thread m_delayedCheckThread;
diff --git a/model/sync-seq-no.h b/model/sync-seq-no.h
index 93013a5..b4329d2 100644
--- a/model/sync-seq-no.h
+++ b/model/sync-seq-no.h
@@ -36,6 +36,16 @@
 {
 public:
   /**
+   * @brief Default constructor.  Creates an zero sequence number with zero session ID (basically is an invalid object)
+   */
+  SeqNo ()
+    : m_valid (false)
+    , m_session (0)
+    , m_seq (0)
+  {
+  }
+  
+  /**
    * @brief Copy constructor
    * @param seq sequence number object to copy from
    */
@@ -51,6 +61,7 @@
   SeqNo &
   operator = (const SeqNo &seq)
   {
+    m_valid = seq.m_valid;
     m_session = seq.m_session;
     m_seq = seq.m_seq;
 
@@ -62,7 +73,8 @@
    * @param seq Sequence number
    */
   SeqNo (uint32_t seq)
-    : m_session (0)
+    : m_valid (true)
+    , m_session (0)
     , m_seq (seq)
   { }
 
@@ -72,7 +84,8 @@
    * @param seq Sequence number
    */
   SeqNo (uint32_t session, uint32_t seq)
-    : m_session (session)
+    : m_valid (true)
+    , m_session (session)
     , m_seq (seq)
   { }
 
@@ -108,6 +121,12 @@
     return m_session == seq.m_session && m_seq == seq.m_seq;
   }
 
+  bool
+  isValid () const
+  {
+    return m_valid;
+  }
+  
   /**
    * @brief Get session id
    */
@@ -121,6 +140,8 @@
   { return m_seq; }
   
 private:
+  bool m_valid;
+  
   /**
    * @brief Session ID (e.g., after crash, application will choose new session ID.
    *
diff --git a/model/sync-state.h b/model/sync-state.h
index 2806fdb..f01e744 100644
--- a/model/sync-state.h
+++ b/model/sync-state.h
@@ -25,6 +25,7 @@
 
 #include "sync-state-leaf-container.h"
 #include <boost/exception/all.hpp>
+#include "boost/tuple/tuple.hpp"
 
 /**
  * \defgroup sync SYNC protocol
@@ -48,7 +49,7 @@
    * @param info name of the leaf
    * @param seq  sequence number of the leaf
    */
-  virtual bool
+  virtual boost::tuple<bool/*inserted*/, bool/*updated*/, SeqNo/*oldSeqNo*/>
   update (NameInfoConstPtr info, const SeqNo &seq) = 0;
 
   /**
diff --git a/test/test_data_fetch_and_publish.cc b/test/test_data_fetch_and_publish.cc
index b227572..a442830 100644
--- a/test/test_data_fetch_and_publish.cc
+++ b/test/test_data_fetch_and_publish.cc
@@ -71,7 +71,7 @@
   string str[5] = {"panda", "express", "tastes", "so", "good"};
 
   for (int i = 0; i < 5; i++) {
-    foo.set(interest + "/" + seq[i], str[i]);
+    foo.set(interest + "/" + "0/" /*session*/ + seq[i], str[i]);
   }
 
   boost::function<void (string, string)> setFunc =
@@ -89,7 +89,7 @@
   BOOST_CHECK_EQUAL(publisher.getHighestSeq(interest, 0), 5);
   BOOST_CHECK_EQUAL(publisher.getRecentData(interest, 0), str[4]);
 
-  fetcher.fetch(interest, 1, 5);
+  fetcher.onUpdate (interest, SeqNo (0,5), SeqNo (0,0));
   // give time for ccnd to react
   sleep(1);
   BOOST_CHECK_EQUAL(foo.toString(), bar.toString());
@@ -99,7 +99,7 @@
     bind(&TestStructApp::erase, &bar, _1, _2);
   fetcher.setDataCallback(eraseFunc);
 
-  fetcher.fetch(interest, 1, 5);
+  fetcher.onUpdate (interest, SeqNo (0,5), SeqNo (0,0));
   // give time for ccnd to react
   sleep(1);
   TestStructApp poo;
diff --git a/test/test_interest_table.cc b/test/test_interest_table.cc
index 7cca0eb..3c39046 100644
--- a/test/test_interest_table.cc
+++ b/test/test_interest_table.cc
@@ -42,15 +42,20 @@
   BOOST_CHECK_NO_THROW (delete table);
 }
 
-void func (const std::string &, uint32_t, uint32_t)
+void funcUpdate (const std::string &, const SeqNo &newSeq, const SeqNo &oldSeq)
 {
-  cout << "func\n";
+  cout << "funcUpdate\n";
+}
+
+void funcRemove (const std::string &)
+{
+  cout << "funcRemove\n";
 }
 
 BOOST_AUTO_TEST_CASE (SyncLogicTest)
 {  
   SyncLogic *logic = 0;
-  BOOST_CHECK_NO_THROW (logic = new SyncLogic ("/prefix", func, make_shared<CcnxWrapper> ()));
+  BOOST_CHECK_NO_THROW (logic = new SyncLogic ("/prefix", funcUpdate, funcRemove, make_shared<CcnxWrapper> ()));
   BOOST_CHECK_EQUAL (logic->getListChecksSize (), 0);
 
   // 0s
diff --git a/test/test_state.cc b/test/test_state.cc
index 00ff467..56810ac 100644
--- a/test/test_state.cc
+++ b/test/test_state.cc
@@ -263,4 +263,32 @@
 
 }
 
+BOOST_AUTO_TEST_CASE (DiffStateDiffTest)
+{
+  DiffStatePtr root = make_shared<DiffState> ();
+
+  DiffStatePtr head = make_shared<DiffState> ();
+  root->setNext (head);
+  
+  head->update (StdNameInfo::FindOrCreate ("3"), SeqNo (1));
+  head->remove (StdNameInfo::FindOrCreate ("1"));
+  
+  DiffStatePtr tail = make_shared<DiffState> ();
+  head->setNext (tail);
+
+  tail->update (StdNameInfo::FindOrCreate ("3"), SeqNo (2));  
+
+  {
+  ostringstream os;
+  os << *root->diff ();
+  string diffState = os.str ();
+  erase_all (diffState, "\n");
+  BOOST_CHECK_EQUAL (diffState,
+                     "<state>"
+                     "<item action=\"remove\"><name>1</name></item>"
+                     "<item action=\"update\"><name>3</name><seq><session>0</session><seqno>2</seqno></seq></item>"
+                     "</state>");
+  }
+}
+
 BOOST_AUTO_TEST_SUITE_END()