diff --git a/core/global-io.hpp b/core/global-io.hpp
index 0fb2fbe..e182dd7 100644
--- a/core/global-io.hpp
+++ b/core/global-io.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2018  Regents of the University of California,
+ * Copyright (c) 2014-2019  Regents of the University of California,
  *                          Arizona Board of Regents,
  *                          Colorado State University,
  *                          University Pierre & Marie Curie, Sorbonne University,
@@ -29,17 +29,28 @@
 
 namespace nfd {
 
-/** \return the global io_service instance
+namespace detail {
+
+/**
+ * @brief Simulator-based IO that implements a few interfaces from boost::asio::io_service
  */
-boost::asio::io_service&
+class SimulatorIo
+{
+public:
+  void
+  post(const std::function<void()>& callback);
+
+  void
+  dispatch(const std::function<void()>& callback);
+};
+
+} // namespace detail
+
+/** \return Simulator-based IO object
+ */
+detail::SimulatorIo&
 getGlobalIoService();
 
-void
-setMainIoService(boost::asio::io_service* mainIo);
-
-void
-setRibIoService(boost::asio::io_service* ribIo);
-
 /** \brief run a function on the main io_service instance
  */
 void
@@ -50,21 +61,12 @@
 void
 runOnRibIoService(const std::function<void()>& f);
 
-boost::asio::io_service&
+detail::SimulatorIo&
 getMainIoService();
 
-boost::asio::io_service&
+detail::SimulatorIo&
 getRibIoService();
 
-#ifdef WITH_TESTS
-/** \brief delete the global io_service instance
- *
- *  It will be recreated at the next invocation of getGlobalIoService.
- */
-void
-resetGlobalIoService();
-#endif
-
 } // namespace nfd
 
 #endif // NFD_CORE_GLOBAL_IO_HPP