core: use markers in StatusDataset and NotificationStream

This commit also refactors FaceMonitor as generic NotificationSubscriber,
and refactors AutoregServer to use FaceMonitor.

refs #1837 #1838

Change-Id: I8b40dfae118853d1224c8290cf92e7cc0daa116f
diff --git a/core/notification-stream.hpp b/core/notification-stream.hpp
new file mode 100644
index 0000000..9a89b4c
--- /dev/null
+++ b/core/notification-stream.hpp
@@ -0,0 +1,81 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014,  Regents of the University of California,
+ *                      Arizona Board of Regents,
+ *                      Colorado State University,
+ *                      University Pierre & Marie Curie, Sorbonne University,
+ *                      Washington University in St. Louis,
+ *                      Beijing Institute of Technology,
+ *                      The University of Memphis
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NFD 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
+ * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef NFD_CORE_NOTIFICATION_STREAM_HPP
+#define NFD_CORE_NOTIFICATION_STREAM_HPP
+
+#include "common.hpp"
+
+#include <ndn-cxx/encoding/encoding-buffer.hpp>
+#include <ndn-cxx/security/key-chain.hpp>
+
+namespace nfd {
+
+/** \brief provides a publisher of Notification Stream
+ *  \sa http://redmine.named-data.net/projects/nfd/wiki/Notification
+ */
+template <class FaceBase>
+class NotificationStream : noncopyable
+{
+public:
+  NotificationStream(FaceBase& face, const Name& prefix, ndn::KeyChain& keyChain)
+    : m_face(face)
+    , m_prefix(prefix)
+    , m_keyChain(keyChain)
+    , m_sequenceNo(0)
+  {
+  }
+
+  virtual
+  ~NotificationStream()
+  {
+  }
+
+  template<typename T> void
+  postNotification(const T& notification)
+  {
+    Name dataName = m_prefix;
+    dataName.appendSequenceNumber(m_sequenceNo);
+
+    shared_ptr<Data> data = make_shared<Data>(dataName);
+    data->setContent(notification.wireEncode());
+    data->setFreshnessPeriod(time::seconds(1));
+
+    m_keyChain.sign(*data);
+    m_face.put(*data);
+
+    ++m_sequenceNo;
+  }
+
+private:
+  FaceBase& m_face;
+  const Name m_prefix;
+  ndn::KeyChain& m_keyChain;
+  uint64_t m_sequenceNo;
+};
+
+} // namespace nfd
+
+#endif // NFD_CORE_NOTIFICATION_STREAM_HPP