diff --git a/ndnx/ndnx-selectors.cpp b/ndnx/ndnx-selectors.cpp
new file mode 100644
index 0000000..3006d0e
--- /dev/null
+++ b/ndnx/ndnx-selectors.cpp
@@ -0,0 +1,157 @@
+#include "ndnx-selectors.h"
+#include "ndnx-common.h"
+#include <boost/lexical_cast.hpp>
+
+using namespace std;
+
+namespace Ndnx {
+
+Selectors::Selectors()
+          : m_maxSuffixComps(-1)
+          , m_minSuffixComps(-1)
+          , m_answerOriginKind(AOK_DEFAULT)
+          , m_interestLifetime(-1.0)
+          , m_scope(NO_SCOPE)
+          , m_childSelector(DEFAULT)
+{
+}
+
+Selectors::Selectors(const Selectors &other)
+{
+  m_maxSuffixComps = other.m_maxSuffixComps;
+  m_minSuffixComps = other.m_minSuffixComps;
+  m_answerOriginKind = other.m_answerOriginKind;
+  m_interestLifetime = other.m_interestLifetime;
+  m_scope = other.m_scope;
+  m_childSelector = other.m_childSelector;
+  m_publisherPublicKeyDigest = other.m_publisherPublicKeyDigest;
+}
+
+Selectors::Selectors(const ndn_parsed_interest *pi)
+          : m_maxSuffixComps(-1)
+          , m_minSuffixComps(-1)
+          , m_answerOriginKind(AOK_DEFAULT)
+          , m_interestLifetime(-1.0)
+          , m_scope(NO_SCOPE)
+          , m_childSelector(DEFAULT)
+{
+  if (pi != NULL)
+  {
+    m_maxSuffixComps = pi->max_suffix_comps;
+    m_minSuffixComps = pi->min_suffix_comps;
+    switch(pi->orderpref)
+    {
+      case 0: m_childSelector = LEFT; break;
+      case 1: m_childSelector = RIGHT; break;
+      default: break;
+    }
+    switch(pi->answerfrom)
+    {
+      case 0x1: m_answerOriginKind = AOK_CS; break;
+      case 0x2: m_answerOriginKind = AOK_NEW; break;
+      case 0x3: m_answerOriginKind = AOK_DEFAULT; break;
+      case 0x4: m_answerOriginKind = AOK_STALE; break;
+      case 0x10: m_answerOriginKind = AOK_EXPIRE; break;
+      default: break;
+    }
+    m_scope = static_cast<Scope> (pi->scope);
+    // scope and interest lifetime do not really matter to receiving application, it's only meaningful to routers
+  }
+}
+
+bool
+Selectors::operator == (const Selectors &other)
+{
+  return m_maxSuffixComps == other.m_maxSuffixComps
+         && m_minSuffixComps == other.m_minSuffixComps
+         && m_answerOriginKind == other.m_answerOriginKind
+         && (m_interestLifetime - other.m_interestLifetime) < 10e-4
+         && m_scope == other.m_scope
+         && m_childSelector == other.m_childSelector;
+}
+
+bool
+Selectors::isEmpty() const
+{
+  return m_maxSuffixComps == -1
+         && m_minSuffixComps == -1
+         && m_answerOriginKind == AOK_DEFAULT
+         && (m_interestLifetime - (-1.0)) < 10e-4
+         && m_scope == NO_SCOPE
+         && m_childSelector == DEFAULT;
+}
+
+
+NdnxCharbufPtr
+Selectors::toNdnxCharbuf() const
+{
+  if (isEmpty())
+  {
+    return NdnxCharbufPtr ();
+  }
+  NdnxCharbufPtr ptr(new NdnxCharbuf());
+  ndn_charbuf *cbuf = ptr->getBuf();
+  ndn_charbuf_append_tt(cbuf, NDN_DTAG_Interest, NDN_DTAG);
+  ndn_charbuf_append_tt(cbuf, NDN_DTAG_Name, NDN_DTAG);
+  ndn_charbuf_append_closer(cbuf); // </Name>
+
+  if (m_maxSuffixComps < m_minSuffixComps)
+  {
+    boost::throw_exception(InterestSelectorException() << error_info_str("MaxSuffixComps = " + boost::lexical_cast<string>(m_maxSuffixComps) + " is smaller than  MinSuffixComps = " + boost::lexical_cast<string>(m_minSuffixComps)));
+  }
+
+  if (m_minSuffixComps > 0)
+  {
+    ndnb_tagged_putf(cbuf, NDN_DTAG_MinSuffixComponents, "%d", m_minSuffixComps);
+  }
+
+  if (m_maxSuffixComps > 0)
+  {
+    ndnb_tagged_putf(cbuf, NDN_DTAG_MaxSuffixComponents, "%d", m_maxSuffixComps);
+  }
+
+  // publisher digest
+
+  // exclude
+
+  if (m_childSelector != DEFAULT)
+  {
+    ndnb_tagged_putf(cbuf, NDN_DTAG_MinSuffixComponents, "%d", (int)m_minSuffixComps);
+  }
+
+  if (m_answerOriginKind != AOK_DEFAULT)
+  {
+    // it was not using "ndnb_tagged_putf" in ndnx c code, no idea why
+    ndn_charbuf_append_tt(cbuf, NDN_DTAG_AnswerOriginKind, NDN_DTAG);
+    ndnb_append_number(cbuf, m_answerOriginKind);
+    ndn_charbuf_append_closer(cbuf); // <AnswerOriginKind>
+  }
+
+  if (m_scope != NO_SCOPE)
+  {
+    ndnb_tagged_putf(cbuf, NDN_DTAG_Scope, "%d", m_scope);
+  }
+
+  if (m_interestLifetime > 0.0)
+  {
+    // Ndnx timestamp unit is weird 1/4096 second
+    // this is from their code
+    unsigned lifetime = 4096 * (m_interestLifetime + 1.0/8192.0);
+    if (lifetime == 0 || lifetime > (30 << 12))
+    {
+      boost::throw_exception(InterestSelectorException() << error_info_str("Ndnx requires 0 < lifetime < 30.0. lifetime= " + boost::lexical_cast<string>(m_interestLifetime)));
+    }
+    unsigned char buf[3] = {0};
+    for (int i = sizeof(buf) - 1; i >= 0; i--, lifetime >>= 8)
+    {
+      buf[i] = lifetime & 0xff;
+    }
+    ndnb_append_tagged_blob(cbuf, NDN_DTAG_InterestLifetime, buf, sizeof(buf));
+  }
+
+  ndn_charbuf_append_closer(cbuf); // </Interest>
+
+  return ptr;
+}
+
+} // Ndnx