diff --git a/src/net/asio-fwd.hpp b/src/net/asio-fwd.hpp
index fb80ee5..788b19d 100644
--- a/src/net/asio-fwd.hpp
+++ b/src/net/asio-fwd.hpp
@@ -22,19 +22,13 @@
 #ifndef NDN_NET_ASIO_FWD_HPP
 #define NDN_NET_ASIO_FWD_HPP
 
-#include <boost/version.hpp>
+namespace ndn {
 
-namespace boost {
-namespace asio {
+class DummyIoService
+{
+public:
+};
 
-#if BOOST_VERSION >= 106600
-class io_context;
-using io_service = io_context;
-#else
-class io_service;
-#endif // BOOST_VERSION >= 106600
-
-} // namespace asio
-} // namespace boost
+} // namespace ndn
 
 #endif // NDN_NET_ASIO_FWD_HPP
diff --git a/src/net/dns.cpp b/src/net/dns.cpp
deleted file mode 100644
index 0043ec9..0000000
--- a/src/net/dns.cpp
+++ /dev/null
@@ -1,160 +0,0 @@
-/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
- * Copyright (c) 2013-2017 Regents of the University of California.
- *
- * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
- *
- * ndn-cxx library is free software: you can redistribute it and/or modify it under the
- * terms of the GNU Lesser General Public License as published by the Free Software
- * Foundation, either version 3 of the License, or (at your option) any later version.
- *
- * ndn-cxx library 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 Lesser General Public License for more details.
- *
- * You should have received copies of the GNU General Public License and GNU Lesser
- * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
- * <http://www.gnu.org/licenses/>.
- *
- * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
- */
-
-#include "dns.hpp"
-#include "../util/scheduler.hpp"
-
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/ip/udp.hpp>
-
-namespace ndn {
-namespace dns {
-
-class Resolver : noncopyable
-{
-public:
-  typedef boost::asio::ip::udp protocol;
-  typedef protocol::resolver::iterator iterator;
-  typedef protocol::resolver::query query;
-
-public:
-  Resolver(boost::asio::io_service& ioService,
-           const AddressSelector& addressSelector)
-    : m_resolver(ioService)
-    , m_addressSelector(addressSelector)
-    , m_scheduler(ioService)
-  {
-    BOOST_ASSERT(m_addressSelector != nullptr);
-  }
-
-  void
-  asyncResolve(const query& q,
-               const SuccessCallback& onSuccess,
-               const ErrorCallback& onError,
-               time::nanoseconds timeout,
-               const shared_ptr<Resolver>& self)
-  {
-    m_onSuccess = onSuccess;
-    m_onError = onError;
-
-    m_resolver.async_resolve(q, bind(&Resolver::onResolveResult, this, _1, _2, self));
-
-    m_resolveTimeout = m_scheduler.scheduleEvent(timeout, bind(&Resolver::onResolveTimeout, this, self));
-  }
-
-  iterator
-  syncResolve(const query& q)
-  {
-    return selectAddress(m_resolver.resolve(q));
-  }
-
-private:
-  void
-  onResolveResult(const boost::system::error_code& error,
-                  iterator it, const shared_ptr<Resolver>& self)
-  {
-    m_scheduler.cancelEvent(m_resolveTimeout);
-    // ensure the Resolver isn't destructed while callbacks are still pending, see #2653
-    m_resolver.get_io_service().post(bind([] (const shared_ptr<Resolver>&) {}, self));
-
-    if (error) {
-      if (error == boost::asio::error::operation_aborted)
-        return;
-
-      if (m_onError)
-        m_onError("Hostname cannot be resolved: " + error.message());
-
-      return;
-    }
-
-    it = selectAddress(it);
-
-    if (it != iterator() && m_onSuccess) {
-      m_onSuccess(it->endpoint().address());
-    }
-    else if (m_onError) {
-      m_onError("No endpoints match the specified address selector");
-    }
-  }
-
-  void
-  onResolveTimeout(const shared_ptr<Resolver>& self)
-  {
-    m_resolver.cancel();
-    // ensure the Resolver isn't destructed while callbacks are still pending, see #2653
-    m_resolver.get_io_service().post(bind([] (const shared_ptr<Resolver>&) {}, self));
-
-    if (m_onError)
-      m_onError("Hostname resolution timed out");
-  }
-
-  iterator
-  selectAddress(iterator it) const
-  {
-    while (it != iterator() &&
-           !m_addressSelector(it->endpoint().address())) {
-      ++it;
-    }
-
-    return it;
-  }
-
-private:
-  protocol::resolver m_resolver;
-
-  AddressSelector m_addressSelector;
-  SuccessCallback m_onSuccess;
-  ErrorCallback m_onError;
-
-  util::scheduler::Scheduler m_scheduler;
-  util::scheduler::EventId m_resolveTimeout;
-};
-
-void
-asyncResolve(const std::string& host,
-             const SuccessCallback& onSuccess,
-             const ErrorCallback& onError,
-             boost::asio::io_service& ioService,
-             const AddressSelector& addressSelector,
-             time::nanoseconds timeout)
-{
-  auto resolver = make_shared<Resolver>(ref(ioService), addressSelector);
-  resolver->asyncResolve(Resolver::query(host, ""), onSuccess, onError, timeout, resolver);
-  // resolver will be destroyed when async operation finishes or ioService stops
-}
-
-IpAddress
-syncResolve(const std::string& host,
-            boost::asio::io_service& ioService,
-            const AddressSelector& addressSelector)
-{
-  Resolver resolver(ioService, addressSelector);
-  auto it = resolver.syncResolve(Resolver::query(host, ""));
-
-  if (it == Resolver::iterator()) {
-    BOOST_THROW_EXCEPTION(Error("No endpoints match the specified address selector"));
-  }
-
-  return it->endpoint().address();
-}
-
-} // namespace dns
-} // namespace ndn
diff --git a/src/net/dns.hpp b/src/net/dns.hpp
deleted file mode 100644
index 961e5bd..0000000
--- a/src/net/dns.hpp
+++ /dev/null
@@ -1,118 +0,0 @@
-/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/*
- * Copyright (c) 2013-2018 Regents of the University of California.
- *
- * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
- *
- * ndn-cxx library is free software: you can redistribute it and/or modify it under the
- * terms of the GNU Lesser General Public License as published by the Free Software
- * Foundation, either version 3 of the License, or (at your option) any later version.
- *
- * ndn-cxx library 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 Lesser General Public License for more details.
- *
- * You should have received copies of the GNU General Public License and GNU Lesser
- * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
- * <http://www.gnu.org/licenses/>.
- *
- * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
- */
-
-#ifndef NDN_NET_DNS_HPP
-#define NDN_NET_DNS_HPP
-
-#include "asio-fwd.hpp"
-#include "../util/time.hpp"
-
-#include <boost/asio/ip/address.hpp>
-
-namespace ndn {
-namespace dns {
-
-typedef boost::asio::ip::address IpAddress;
-typedef function<bool (const IpAddress& address)> AddressSelector;
-
-struct AnyAddress
-{
-  bool
-  operator()(const IpAddress& address) const
-  {
-    return true;
-  }
-};
-
-struct Ipv4Only
-{
-  bool
-  operator()(const IpAddress& address) const
-  {
-    return address.is_v4();
-  }
-};
-
-struct Ipv6Only
-{
-  bool
-  operator()(const IpAddress& address) const
-  {
-    return address.is_v6();
-  }
-};
-
-struct Error : public std::runtime_error
-{
-  explicit
-  Error(const std::string& what)
-    : std::runtime_error(what)
-  {
-  }
-};
-
-typedef function<void (const IpAddress& address)> SuccessCallback;
-typedef function<void (const std::string& reason)> ErrorCallback;
-
-/** \brief Asynchronously resolve host
- *
- * If an address selector predicate is specified, then each resolved IP address
- * is checked against the predicate.
- *
- * Available address selector predicates:
- *
- * - dns::AnyAddress()
- * - dns::Ipv4Address()
- * - dns::Ipv6Address()
- *
- * \warning Even after the DNS resolution has timed out, it's possible that
- *          \p ioService keeps running and \p onSuccess is invoked at a later time.
- *          This could cause segmentation fault if \p onSuccess is deallocated.
- *          To stop the io_service, explicitly invoke \p ioService.stop().
- */
-void
-asyncResolve(const std::string& host,
-             const SuccessCallback& onSuccess,
-             const ErrorCallback& onError,
-             boost::asio::io_service& ioService,
-             const AddressSelector& addressSelector = AnyAddress(),
-             time::nanoseconds timeout = 4_s);
-
-/** \brief Synchronously resolve host
- *
- * If an address selector predicate is specified, then each resolved IP address
- * is checked against the predicate.
- *
- * Available address selector predicates:
- *
- * - dns::AnyAddress()
- * - dns::Ipv4Address()
- * - dns::Ipv6Address()
- */
-IpAddress
-syncResolve(const std::string& host,
-            boost::asio::io_service& ioService,
-            const AddressSelector& addressSelector = AnyAddress());
-
-} // namespace dns
-} // namespace ndn
-
-#endif // NDN_NET_DNS_HPP
diff --git a/src/net/face-uri.cpp b/src/net/face-uri.cpp
index 97fe0f7..c91add4 100644
--- a/src/net/face-uri.cpp
+++ b/src/net/face-uri.cpp
@@ -28,7 +28,7 @@
 #include "face-uri.hpp"
 
 #include "address-converter.hpp"
-#include "dns.hpp"
+// #include "dns.hpp"
 #include "util/string-helper.hpp"
 
 #include <boost/algorithm/string.hpp>
@@ -245,7 +245,7 @@
   canonize(const FaceUri& faceUri,
            const FaceUri::CanonizeSuccessCallback& onSuccess,
            const FaceUri::CanonizeFailureCallback& onFailure,
-           boost::asio::io_service& io, time::nanoseconds timeout) const = 0;
+           time::nanoseconds timeout) const = 0;
 };
 
 template<typename Protocol>
@@ -261,95 +261,97 @@
   bool
   isCanonical(const FaceUri& faceUri) const override
   {
-    if (faceUri.getPort().empty()) {
-      return false;
-    }
-    if (!faceUri.getPath().empty()) {
-      return false;
-    }
+    BOOST_THROW_EXCEPTION(std::runtime_error("IP host canonization not supported"));
+    // if (faceUri.getPort().empty()) {
+    //   return false;
+    // }
+    // if (!faceUri.getPath().empty()) {
+    //   return false;
+    // }
 
-    boost::system::error_code ec;
-    auto addr = ip::addressFromString(unescapeHost(faceUri.getHost()), ec);
-    if (ec) {
-      return false;
-    }
+    // boost::system::error_code ec;
+    // auto addr = ip::addressFromString(unescapeHost(faceUri.getHost()), ec);
+    // if (ec) {
+    //   return false;
+    // }
 
-    bool hasCorrectScheme = (faceUri.getScheme() == m_v4Scheme && addr.is_v4()) ||
-                            (faceUri.getScheme() == m_v6Scheme && addr.is_v6());
-    if (!hasCorrectScheme) {
-      return false;
-    }
+    // bool hasCorrectScheme = (faceUri.getScheme() == m_v4Scheme && addr.is_v4()) ||
+    //                         (faceUri.getScheme() == m_v6Scheme && addr.is_v6());
+    // if (!hasCorrectScheme) {
+    //   return false;
+    // }
 
-    auto checkAddressWithUri = [] (const boost::asio::ip::address& addr,
-                                   const FaceUri& faceUri) -> bool {
-      if (addr.is_v4() || !addr.to_v6().is_link_local()) {
-        return addr.to_string() == faceUri.getHost();
-      }
+    // auto checkAddressWithUri = [] (const boost::asio::ip::address& addr,
+    //                                const FaceUri& faceUri) -> bool {
+    //   if (addr.is_v4() || !addr.to_v6().is_link_local()) {
+    //     return addr.to_string() == faceUri.getHost();
+    //   }
 
-      std::vector<std::string> addrFields, faceUriFields;
-      std::string addrString = addr.to_string();
-      std::string faceUriString = faceUri.getHost();
+    //   std::vector<std::string> addrFields, faceUriFields;
+    //   std::string addrString = addr.to_string();
+    //   std::string faceUriString = faceUri.getHost();
 
-      boost::algorithm::split(addrFields, addrString, boost::is_any_of("%"));
-      boost::algorithm::split(faceUriFields, faceUriString, boost::is_any_of("%"));
-      if (addrFields.size() != 2 || faceUriFields.size() != 2) {
-        return false;
-      }
+    //   boost::algorithm::split(addrFields, addrString, boost::is_any_of("%"));
+    //   boost::algorithm::split(faceUriFields, faceUriString, boost::is_any_of("%"));
+    //   if (addrFields.size() != 2 || faceUriFields.size() != 2) {
+    //     return false;
+    //   }
 
-      if (faceUriFields[1].size() > 2 && faceUriFields[1].compare(0, 2, "25") == 0) {
-        // %25... is accepted, but not a canonical form
-        return false;
-      }
+    //   if (faceUriFields[1].size() > 2 && faceUriFields[1].compare(0, 2, "25") == 0) {
+    //     // %25... is accepted, but not a canonical form
+    //     return false;
+    //   }
 
-      return addrFields[0] == faceUriFields[0] &&
-             addrFields[1] == faceUriFields[1];
-    };
+    //   return addrFields[0] == faceUriFields[0] &&
+    //          addrFields[1] == faceUriFields[1];
+    // };
 
-    return checkAddressWithUri(addr, faceUri) && checkAddress(addr).first;
+    // return checkAddressWithUri(addr, faceUri) && checkAddress(addr).first;
   }
 
   void
   canonize(const FaceUri& faceUri,
            const FaceUri::CanonizeSuccessCallback& onSuccess,
            const FaceUri::CanonizeFailureCallback& onFailure,
-           boost::asio::io_service& io, time::nanoseconds timeout) const override
+           time::nanoseconds timeout) const override
   {
-    if (this->isCanonical(faceUri)) {
-      onSuccess(faceUri);
-      return;
-    }
+    BOOST_THROW_EXCEPTION(std::runtime_error("IP host canonization not supported"));
+    // if (this->isCanonical(faceUri)) {
+    //   onSuccess(faceUri);
+    //   return;
+    // }
 
-    // make a copy because caller may modify faceUri
-    auto uri = make_shared<FaceUri>(faceUri);
-    boost::system::error_code ec;
-    auto ipAddress = ip::addressFromString(unescapeHost(faceUri.getHost()), ec);
-    if (!ec) {
-      // No need to resolve IP address if host is already an IP
-      if ((faceUri.getScheme() == m_v4Scheme && !ipAddress.is_v4()) ||
-          (faceUri.getScheme() == m_v6Scheme && !ipAddress.is_v6())) {
-        return onFailure("IPv4/v6 mismatch");
-      }
+    // // make a copy because caller may modify faceUri
+    // auto uri = make_shared<FaceUri>(faceUri);
+    // boost::system::error_code ec;
+    // auto ipAddress = ip::addressFromString(unescapeHost(faceUri.getHost()), ec);
+    // if (!ec) {
+    //   // No need to resolve IP address if host is already an IP
+    //   if ((faceUri.getScheme() == m_v4Scheme && !ipAddress.is_v4()) ||
+    //       (faceUri.getScheme() == m_v6Scheme && !ipAddress.is_v6())) {
+    //     return onFailure("IPv4/v6 mismatch");
+    //   }
 
-      onDnsSuccess(uri, onSuccess, onFailure, ipAddress);
-    }
-    else {
-      dns::AddressSelector addressSelector;
-      if (faceUri.getScheme() == m_v4Scheme) {
-        addressSelector = dns::Ipv4Only();
-      }
-      else if (faceUri.getScheme() == m_v6Scheme) {
-        addressSelector = dns::Ipv6Only();
-      }
-      else {
-        BOOST_ASSERT(faceUri.getScheme() == m_baseScheme);
-        addressSelector = dns::AnyAddress();
-      }
+    //   onDnsSuccess(uri, onSuccess, onFailure, ipAddress);
+    // }
+    // else {
+    //   dns::AddressSelector addressSelector;
+    //   if (faceUri.getScheme() == m_v4Scheme) {
+    //     addressSelector = dns::Ipv4Only();
+    //   }
+    //   else if (faceUri.getScheme() == m_v6Scheme) {
+    //     addressSelector = dns::Ipv6Only();
+    //   }
+    //   else {
+    //     BOOST_ASSERT(faceUri.getScheme() == m_baseScheme);
+    //     addressSelector = dns::AnyAddress();
+    //   }
 
-      dns::asyncResolve(unescapeHost(faceUri.getHost()),
-        bind(&IpHostCanonizeProvider<Protocol>::onDnsSuccess, this, uri, onSuccess, onFailure, _1),
-        bind(&IpHostCanonizeProvider<Protocol>::onDnsFailure, this, uri, onFailure, _1),
-        io, addressSelector, timeout);
-    }
+    //   dns::asyncResolve(unescapeHost(faceUri.getHost()),
+    //     bind(&IpHostCanonizeProvider<Protocol>::onDnsSuccess, this, uri, onSuccess, onFailure, _1),
+    //     bind(&IpHostCanonizeProvider<Protocol>::onDnsFailure, this, uri, onFailure, _1),
+    //     io, addressSelector, timeout);
+    // }
   }
 
 protected:
@@ -366,54 +368,54 @@
   }
 
 private:
-  void
-  onDnsSuccess(const shared_ptr<FaceUri>& faceUri,
-               const FaceUri::CanonizeSuccessCallback& onSuccess,
-               const FaceUri::CanonizeFailureCallback& onFailure,
-               const dns::IpAddress& ipAddress) const
-  {
-    bool isOk = false;
-    std::string reason;
-    std::tie(isOk, reason) = this->checkAddress(ipAddress);
-    if (!isOk) {
-      return onFailure(reason);
-    }
+  // void
+  // onDnsSuccess(const shared_ptr<FaceUri>& faceUri,
+  //              const FaceUri::CanonizeSuccessCallback& onSuccess,
+  //              const FaceUri::CanonizeFailureCallback& onFailure,
+  //              const dns::IpAddress& ipAddress) const
+  // {
+  //   bool isOk = false;
+  //   std::string reason;
+  //   std::tie(isOk, reason) = this->checkAddress(ipAddress);
+  //   if (!isOk) {
+  //     return onFailure(reason);
+  //   }
 
-    uint16_t port = 0;
-    if (faceUri->getPort().empty()) {
-      port = ipAddress.is_multicast() ? m_defaultMulticastPort : m_defaultUnicastPort;
-    }
-    else {
-      try {
-        port = boost::lexical_cast<uint16_t>(faceUri->getPort());
-      }
-      catch (const boost::bad_lexical_cast&) {
-        return onFailure("invalid port number '" + faceUri->getPort() + "'");
-      }
-    }
+  //   uint16_t port = 0;
+  //   if (faceUri->getPort().empty()) {
+  //     port = ipAddress.is_multicast() ? m_defaultMulticastPort : m_defaultUnicastPort;
+  //   }
+  //   else {
+  //     try {
+  //       port = boost::lexical_cast<uint16_t>(faceUri->getPort());
+  //     }
+  //     catch (const boost::bad_lexical_cast&) {
+  //       return onFailure("invalid port number '" + faceUri->getPort() + "'");
+  //     }
+  //   }
 
-    FaceUri canonicalUri(typename Protocol::endpoint(ipAddress, port));
-    BOOST_ASSERT(canonicalUri.isCanonical());
-    onSuccess(canonicalUri);
-  }
+  //   FaceUri canonicalUri(typename Protocol::endpoint(ipAddress, port));
+  //   BOOST_ASSERT(canonicalUri.isCanonical());
+  //   onSuccess(canonicalUri);
+  // }
 
-  void
-  onDnsFailure(const shared_ptr<FaceUri>& faceUri,
-               const FaceUri::CanonizeFailureCallback& onFailure,
-               const std::string& reason) const
-  {
-    onFailure(reason);
-  }
+  // void
+  // onDnsFailure(const shared_ptr<FaceUri>& faceUri,
+  //              const FaceUri::CanonizeFailureCallback& onFailure,
+  //              const std::string& reason) const
+  // {
+  //   onFailure(reason);
+  // }
 
   /** \brief when overriden in a subclass, check the IP address is allowable
    *  \return (true,ignored) if the address is allowable;
    *          (false,reason) if the address is not allowable.
    */
-  virtual std::pair<bool, std::string>
-  checkAddress(const dns::IpAddress& ipAddress) const
-  {
-    return {true, ""};
-  }
+  // virtual std::pair<bool, std::string>
+  // checkAddress(const dns::IpAddress& ipAddress) const
+  // {
+  //   return {true, ""};
+  // }
 
   static std::string
   unescapeHost(std::string host)
@@ -451,14 +453,14 @@
   }
 
 protected:
-  std::pair<bool, std::string>
-  checkAddress(const dns::IpAddress& ipAddress) const override
-  {
-    if (ipAddress.is_multicast()) {
-      return {false, "cannot use multicast address"};
-    }
-    return {true, ""};
-  }
+  // std::pair<bool, std::string>
+  // checkAddress(const dns::IpAddress& ipAddress) const override
+  // {
+  //   if (ipAddress.is_multicast()) {
+  //     return {false, "cannot use multicast address"};
+  //   }
+  //   return {true, ""};
+  // }
 };
 
 class EtherCanonizeProvider : public CanonizeProvider
@@ -488,7 +490,7 @@
   canonize(const FaceUri& faceUri,
            const FaceUri::CanonizeSuccessCallback& onSuccess,
            const FaceUri::CanonizeFailureCallback& onFailure,
-           boost::asio::io_service& io, time::nanoseconds timeout) const override
+           time::nanoseconds timeout) const override
   {
     auto addr = ethernet::Address::fromString(faceUri.getHost());
     if (addr.isNull()) {
@@ -520,7 +522,7 @@
   canonize(const FaceUri& faceUri,
            const FaceUri::CanonizeSuccessCallback& onSuccess,
            const FaceUri::CanonizeFailureCallback& onFailure,
-           boost::asio::io_service& io, time::nanoseconds timeout) const override
+           time::nanoseconds timeout) const override
   {
     if (faceUri.getHost().empty()) {
       onFailure("network interface name is missing");
@@ -566,7 +568,7 @@
   canonize(const FaceUri& faceUri,
            const FaceUri::CanonizeSuccessCallback& onSuccess,
            const FaceUri::CanonizeFailureCallback& onFailure,
-           boost::asio::io_service& io, time::nanoseconds timeout) const override
+           time::nanoseconds timeout) const override
   {
     if (this->isCanonical(faceUri)) {
       onSuccess(faceUri);
@@ -645,7 +647,7 @@
 void
 FaceUri::canonize(const CanonizeSuccessCallback& onSuccess,
                   const CanonizeFailureCallback& onFailure,
-                  boost::asio::io_service& io, time::nanoseconds timeout) const
+                  time::nanoseconds timeout) const
 {
   const CanonizeProvider* cp = getCanonizeProvider(this->getScheme());
   if (cp == nullptr) {
@@ -660,7 +662,7 @@
   cp->canonize(*this,
                onSuccess ? onSuccess : successNop,
                onFailure ? onFailure : failureNop,
-               io, timeout);
+               timeout);
 }
 
 } // namespace ndn
diff --git a/src/net/face-uri.hpp b/src/net/face-uri.hpp
index 7461576..5f40e30 100644
--- a/src/net/face-uri.hpp
+++ b/src/net/face-uri.hpp
@@ -168,7 +168,6 @@
    *  \param onSuccess function to call after this FaceUri is converted to canonical form
    *  \note A new FaceUri in canonical form will be created; this FaceUri is unchanged.
    *  \param onFailure function to call if this FaceUri cannot be converted to canonical form
-   *  \param io        reference to `boost::asio::io_service` instance
    *  \param timeout   maximum allowable duration of the operations.
    *                   It's intentional not to provide a default value: the caller should set
    *                   a reasonable value in balance between network delay and user experience.
@@ -176,7 +175,6 @@
   void
   canonize(const CanonizeSuccessCallback& onSuccess,
            const CanonizeFailureCallback& onFailure,
-           boost::asio::io_service& io,
            time::nanoseconds timeout) const;
 
 private: