diff --git a/src/chatroom-discovery-logic.cpp b/src/chatroom-discovery-logic.cpp
new file mode 100644
index 0000000..048d121
--- /dev/null
+++ b/src/chatroom-discovery-logic.cpp
@@ -0,0 +1,221 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2013, Regents of the University of California
+ *                     Yingdi Yu
+ *
+ * BSD license, See the LICENSE file for more information
+ *
+ * Author: Mengjin Yan <jane.yan0129@gmail.com>
+ * Author: Yingdi Yu <yingdi@cs.ucla.edu>
+ */
+
+#include "chatroom-discovery-logic.hpp"
+
+
+namespace chronos {
+
+const size_t ChatroomDiscoveryLogic::OFFSET_CHATROOM_NAME = 4;
+const size_t ChatroomDiscoveryLogic::DISCOVERY_INTEREST_NAME_SIZE = 4;
+const size_t ChatroomDiscoveryLogic::REFRESHING_INTEREST_NAME_SIZE = 5;
+const time::milliseconds ChatroomDiscoveryLogic::DEFAULT_REFRESHING_TIMER(10000);
+const Name ChatroomDiscoveryLogic::DISCOVERY_PREFIX("/ndn/broadcast/chronochat/chatroom-list");
+const time::seconds ChatroomDiscoveryLogic::m_discoveryInterval(600);
+
+ChatroomDiscoveryLogic::ChatroomDiscoveryLogic(shared_ptr<ndn::Face> face,
+                                               const UpdateCallback& updateCallback)
+  : m_face(face)
+  , m_scheduler(face->getIoService())
+  , m_onUpdate(updateCallback)
+{
+
+  m_face->setInterestFilter(DISCOVERY_PREFIX,
+                            bind(&ChatroomDiscoveryLogic::onDiscoveryInterest,
+                                 this, _1, _2),
+                            bind(&ChatroomDiscoveryLogic::onPrefixRegistrationFailed,
+                                 this, _1));
+}
+
+void
+ChatroomDiscoveryLogic::addLocalChatroom(const ChatroomInfo& chatroom)
+{
+  m_localChatrooms[chatroom.getName()] = chatroom;
+  m_chatrooms[chatroom.getName()] = chatroom; // no need to discover local chatroom
+}
+
+void
+ChatroomDiscoveryLogic::removeLocalChatroom(const Name::Component& chatroomName)
+{
+  m_localChatrooms.erase(chatroomName);
+  m_chatrooms.erase(chatroomName);
+}
+
+void
+ChatroomDiscoveryLogic::sendDiscoveryInterest()
+{
+  Interest discovery(DISCOVERY_PREFIX);
+  discovery.setMustBeFresh(true);
+  discovery.setInterestLifetime(time::milliseconds(10000));
+
+  Exclude exclude;
+  Chatrooms::iterator it;
+  for (it = m_chatrooms.begin(); it != m_chatrooms.end(); ++it) {
+    exclude.excludeOne(it->first);
+  }
+  discovery.setExclude(exclude);
+
+  m_face->expressInterest(discovery,
+                          bind(&ChatroomDiscoveryLogic::onReceiveData, this,
+                               _1, _2, false),
+                          bind(&ChatroomDiscoveryLogic::onDiscoveryInterestTimeout, this,
+                               _1));
+
+}
+
+void
+ChatroomDiscoveryLogic::onDiscoveryInterest(const Name& name, const Interest& interest)
+{
+  if (m_localChatrooms.empty())
+    return;
+
+  if (interest.getName() == DISCOVERY_PREFIX) {
+    // discovery
+    for (Chatrooms::const_iterator it = m_localChatrooms.begin();
+         it != m_localChatrooms.end(); ++it) {
+
+      if (!interest.getExclude().empty() &&
+          interest.getExclude().isExcluded(it->first))
+        continue;
+
+
+      Name dataName(interest.getName());
+      dataName.append(it->first);
+
+      shared_ptr<Data> chatroomInfo = make_shared<Data>(dataName);
+      chatroomInfo->setFreshnessPeriod(time::seconds(10));
+      chatroomInfo->setContent(it->second.wireEncode());
+
+      m_keyChain.sign(*chatroomInfo);
+      m_face->put(*chatroomInfo);
+      break;
+    }
+    return;
+  }
+
+  if (DISCOVERY_PREFIX.isPrefixOf(interest.getName()) &&
+      interest.getName().size() == REFRESHING_INTEREST_NAME_SIZE) {
+    // refreshing
+    Chatrooms::const_iterator it =
+      m_localChatrooms.find(interest.getName().get(OFFSET_CHATROOM_NAME));
+
+    if (it == m_localChatrooms.end())
+      return;
+
+    shared_ptr<Data> chatroomInfo = make_shared<Data>(interest.getName());
+    chatroomInfo->setFreshnessPeriod(time::seconds(10));
+    chatroomInfo->setContent(it->second.wireEncode());
+
+    m_keyChain.sign(*chatroomInfo);
+    m_face->put(*chatroomInfo);
+
+    return;
+  }
+}
+
+void
+ChatroomDiscoveryLogic::onPrefixRegistrationFailed(const Name& name)
+{
+}
+
+void
+ChatroomDiscoveryLogic::refreshChatroom(const Name::Component& chatroomName)
+{
+  Name name = DISCOVERY_PREFIX;
+  name.append(chatroomName);
+
+  BOOST_ASSERT(name.size() == REFRESHING_INTEREST_NAME_SIZE);
+
+  Interest discovery(name);
+  discovery.setMustBeFresh(true);
+  discovery.setInterestLifetime(time::milliseconds(10000));
+
+  m_face->expressInterest(discovery,
+                          bind(&ChatroomDiscoveryLogic::onReceiveData, this,
+                               _1, _2, true),
+                          bind(&ChatroomDiscoveryLogic::onRefreshingInterestTimeout, this,
+                               _1));
+
+}
+
+void
+ChatroomDiscoveryLogic::onReceiveData(const ndn::Interest& interest,
+                                      const ndn::Data& data,
+                                      const bool isRefreshing)
+{
+  Name::Component chatroomName = data.getName().get(OFFSET_CHATROOM_NAME);
+
+  ChatroomInfo chatroom;
+  chatroom.wireDecode(data.getContent().blockFromValue());
+  chatroom.setName(chatroomName);
+
+  // Tmp Disabled
+  // if (chatroom.getTrustModel() == ChatroomInfo::TRUST_MODEL_WEBOFTRUST)
+  //   addContacts(chatroom);
+
+
+  m_chatrooms[chatroomName] = chatroom;
+  m_onUpdate(chatroom, true); //add
+
+  time::milliseconds refreshingTime;
+  if (data.getFreshnessPeriod() > DEFAULT_REFRESHING_TIMER)
+    refreshingTime = data.getFreshnessPeriod();
+  else
+    refreshingTime = DEFAULT_REFRESHING_TIMER;
+
+  m_scheduler.scheduleEvent(refreshingTime,
+                            bind(&ChatroomDiscoveryLogic::refreshChatroom, this, chatroomName));
+
+  if (!isRefreshing)
+    sendDiscoveryInterest();
+}
+
+void
+ChatroomDiscoveryLogic::onRefreshingInterestTimeout(const ndn::Interest& interest)
+{
+  Name::Component chatroomName = interest.getName().get(OFFSET_CHATROOM_NAME);
+
+  Chatrooms::iterator it = m_chatrooms.find(chatroomName);
+  if (it != m_chatrooms.end()) {
+    m_onUpdate(it->second, false); //delete
+    m_chatrooms.erase(it);
+  }
+}
+
+
+void
+ChatroomDiscoveryLogic::onDiscoveryInterestTimeout(const Interest& interest)
+{
+  m_scheduler.scheduleEvent(m_discoveryInterval,
+                            bind(&ChatroomDiscoveryLogic::sendDiscoveryInterest, this));
+}
+
+void
+ChatroomDiscoveryLogic::addContacts(ChatroomInfo& chatroom)
+{
+  // Tmp Disabled
+
+  // std::vector<Name>::const_iterator nameIt;
+  // std::vector<shared_ptr<Contact> >::iterator contactIt;
+  // ContactList contactList;
+  // m_contactManager->getContactList(contactList);
+
+  // for (contactIt = contactList.begin();
+  //      contactIt != contactList.end(); ++contactIt) {
+  //   nameIt = std::find(chatroom.getParticipants().begin(),
+  //                 chatroom.getParticipants().end(), (*contactIt)->getNameSpace());
+  //   if (nameIt != chatroom.getParticipants().end())
+  //     chatroom.addContact(*nameIt);
+  // }
+}
+
+
+} //namespace chronos