diff --git a/lib/allocator.h b/lib/allocator.h
index 97b9a41..400b0e0 100644
--- a/lib/allocator.h
+++ b/lib/allocator.h
@@ -25,7 +25,7 @@
 #ifndef ALLOCATOR_H
 #define ALLOCATOR_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #ifndef _WIN32
 #  include <sys/uio.h>
@@ -34,7 +34,7 @@
 #include <cassert>
 #include <utility>
 
-#include "template.h"
+#include <nghttp2/template.h>
 
 namespace nghttp2 {
 
diff --git a/lib/asio_client_request.cc b/lib/asio_client_request.cc
index a81e213..64a5246 100644
--- a/lib/asio_client_request.cc
+++ b/lib/asio_client_request.cc
@@ -22,13 +22,13 @@
  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_client.h>
 
 #include "asio_client_request_impl.h"
 
-#include "template.h"
+#include <nghttp2/template.h>
 
 namespace nghttp2 {
 namespace asio_http2 {
diff --git a/lib/asio_client_request_impl.cc b/lib/asio_client_request_impl.cc
index 1e4e2dd..55d7534 100644
--- a/lib/asio_client_request_impl.cc
+++ b/lib/asio_client_request_impl.cc
@@ -25,8 +25,8 @@
 #include "asio_client_request_impl.h"
 
 #include "asio_client_stream.h"
-#include "asio_client_session_impl.h"
-#include "template.h"
+#include <nghttp2/asio_client_session_impl.h>
+#include <nghttp2/template.h>
 
 namespace nghttp2 {
 namespace asio_http2 {
diff --git a/lib/asio_client_request_impl.h b/lib/asio_client_request_impl.h
index e0d43d2..1c0b79f 100644
--- a/lib/asio_client_request_impl.h
+++ b/lib/asio_client_request_impl.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_CLIENT_REQUEST_IMPL_H
 #define ASIO_CLIENT_REQUEST_IMPL_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_client.h>
 
diff --git a/lib/asio_client_response.cc b/lib/asio_client_response.cc
index 56b8072..a3413f3 100644
--- a/lib/asio_client_response.cc
+++ b/lib/asio_client_response.cc
@@ -22,13 +22,13 @@
  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_client.h>
 
 #include "asio_client_response_impl.h"
 
-#include "template.h"
+#include <nghttp2/template.h>
 
 namespace nghttp2 {
 namespace asio_http2 {
diff --git a/lib/asio_client_response_impl.cc b/lib/asio_client_response_impl.cc
index bd2cdf5..4f02cfa 100644
--- a/lib/asio_client_response_impl.cc
+++ b/lib/asio_client_response_impl.cc
@@ -24,7 +24,7 @@
  */
 #include "asio_client_response_impl.h"
 
-#include "template.h"
+#include <nghttp2/template.h>
 
 namespace nghttp2 {
 namespace asio_http2 {
diff --git a/lib/asio_client_response_impl.h b/lib/asio_client_response_impl.h
index 524d728..837964f 100644
--- a/lib/asio_client_response_impl.h
+++ b/lib/asio_client_response_impl.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_CLIENT_RESPONSE_IMPL_H
 #define ASIO_CLIENT_RESPONSE_IMPL_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_client.h>
 
diff --git a/lib/asio_client_session.cc b/lib/asio_client_session.cc
index 5cf01c7..796c1ae 100644
--- a/lib/asio_client_session.cc
+++ b/lib/asio_client_session.cc
@@ -22,14 +22,14 @@
  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_client.h>
 
 #include "asio_client_session_tcp_impl.h"
 #include "asio_client_session_tls_impl.h"
 #include "asio_common.h"
-#include "template.h"
+#include <nghttp2/template.h>
 
 namespace nghttp2 {
 namespace asio_http2 {
@@ -87,6 +87,12 @@ session::session(boost::asio::io_service &io_service,
   impl_->start_resolve(host, service);
 }
 
+session::session(std::shared_ptr<session_impl> impl)
+    : impl_{impl}
+{
+}
+
+
 session::~session() {}
 
 session::session(session &&other) noexcept : impl_(std::move(other.impl_)) {}
diff --git a/lib/asio_client_session_impl.cc b/lib/asio_client_session_impl.cc
index b96824d..375c073 100644
--- a/lib/asio_client_session_impl.cc
+++ b/lib/asio_client_session_impl.cc
@@ -22,7 +22,7 @@
  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-#include "asio_client_session_impl.h"
+#include "nghttp2/asio_client_session_impl.h"
 
 #include <iostream>
 
@@ -30,7 +30,7 @@
 #include "asio_client_request_impl.h"
 #include "asio_client_response_impl.h"
 #include "asio_common.h"
-#include "template.h"
+#include <nghttp2/template.h>
 #include "util.h"
 #include "http2.h"
 
diff --git a/lib/asio_client_session_tcp_impl.h b/lib/asio_client_session_tcp_impl.h
index 0b6ae93..d2c70cf 100644
--- a/lib/asio_client_session_tcp_impl.h
+++ b/lib/asio_client_session_tcp_impl.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_CLIENT_SESSION_TCP_IMPL_H
 #define ASIO_CLIENT_SESSION_TCP_IMPL_H
 
-#include "asio_client_session_impl.h"
+#include <nghttp2/asio_client_session_impl.h>
 
 #include <nghttp2/asio_http2_client.h>
 
diff --git a/lib/asio_client_session_tls_impl.h b/lib/asio_client_session_tls_impl.h
index 645c60f..5d04d0d 100644
--- a/lib/asio_client_session_tls_impl.h
+++ b/lib/asio_client_session_tls_impl.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_CLIENT_SESSION_TLS_IMPL_H
 #define ASIO_CLIENT_SESSION_TLS_IMPL_H
 
-#include "asio_client_session_impl.h"
+#include <nghttp2/asio_client_session_impl.h>
 
 #include <nghttp2/asio_http2_client.h>
 
diff --git a/lib/asio_client_stream.cc b/lib/asio_client_stream.cc
index 2d3aa5b..b519040 100644
--- a/lib/asio_client_stream.cc
+++ b/lib/asio_client_stream.cc
@@ -26,7 +26,7 @@
 
 #include "asio_client_request_impl.h"
 #include "asio_client_response_impl.h"
-#include "asio_client_session_impl.h"
+#include <nghttp2/asio_client_session_impl.h>
 
 namespace nghttp2 {
 namespace asio_http2 {
diff --git a/lib/asio_client_stream.h b/lib/asio_client_stream.h
index e3e027a..a27333b 100644
--- a/lib/asio_client_stream.h
+++ b/lib/asio_client_stream.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_CLIENT_STREAM_H
 #define ASIO_CLIENT_STREAM_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_client.h>
 
diff --git a/lib/asio_client_tls_context.h b/lib/asio_client_tls_context.h
index 6287dab..677ed45 100644
--- a/lib/asio_client_tls_context.h
+++ b/lib/asio_client_tls_context.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_CLIENT_TLS_CONTEXT_H
 #define ASIO_CLIENT_TLS_CONTEXT_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_client.h>
 
diff --git a/lib/asio_common.cc b/lib/asio_common.cc
index 428dbd6..4d1de3b 100644
--- a/lib/asio_common.cc
+++ b/lib/asio_common.cc
@@ -28,7 +28,7 @@
 #include <memory>
 
 #include "util.h"
-#include "template.h"
+#include <nghttp2/template.h>
 #include "http2.h"
 
 namespace nghttp2 {
diff --git a/lib/asio_common.h b/lib/asio_common.h
index 7eacfa5..70fceae 100644
--- a/lib/asio_common.h
+++ b/lib/asio_common.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_COMMON_H
 #define ASIO_COMMON_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <string>
 
diff --git a/lib/asio_io_service_pool.h b/lib/asio_io_service_pool.h
index 9c11533..6bee72a 100644
--- a/lib/asio_io_service_pool.h
+++ b/lib/asio_io_service_pool.h
@@ -37,7 +37,7 @@
 #ifndef ASIO_IO_SERVICE_POOL_H
 #define ASIO_IO_SERVICE_POOL_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <vector>
 #include <memory>
diff --git a/lib/asio_server.h b/lib/asio_server.h
index 1190e32..9c1c0a4 100644
--- a/lib/asio_server.h
+++ b/lib/asio_server.h
@@ -37,7 +37,7 @@
 #ifndef ASIO_SERVER_H
 #define ASIO_SERVER_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <string>
 #include <vector>
diff --git a/lib/asio_server_connection.h b/lib/asio_server_connection.h
index a948965..b402ca2 100644
--- a/lib/asio_server_connection.h
+++ b/lib/asio_server_connection.h
@@ -37,7 +37,7 @@
 #ifndef ASIO_SERVER_CONNECTION_H
 #define ASIO_SERVER_CONNECTION_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <memory>
 
@@ -49,7 +49,7 @@
 #include "asio_server_http2_handler.h"
 #include "asio_server_serve_mux.h"
 #include "util.h"
-#include "template.h"
+#include <nghttp2/template.h>
 
 #if BOOST_VERSION >= 107000
 #  define GET_IO_SERVICE(s)                                                    \
diff --git a/lib/asio_server_http2.cc b/lib/asio_server_http2.cc
index 02d3d19..69d6adf 100644
--- a/lib/asio_server_http2.cc
+++ b/lib/asio_server_http2.cc
@@ -22,13 +22,13 @@
  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_server.h>
 
 #include "asio_server_http2_impl.h"
 #include "asio_server.h"
-#include "template.h"
+#include <nghttp2/template.h>
 
 namespace nghttp2 {
 
diff --git a/lib/asio_server_http2_handler.cc b/lib/asio_server_http2_handler.cc
index c1fc195..d75c8db 100644
--- a/lib/asio_server_http2_handler.cc
+++ b/lib/asio_server_http2_handler.cc
@@ -33,7 +33,7 @@
 #include "asio_server_response_impl.h"
 #include "http2.h"
 #include "util.h"
-#include "template.h"
+#include <nghttp2/template.h>
 
 namespace nghttp2 {
 
diff --git a/lib/asio_server_http2_handler.h b/lib/asio_server_http2_handler.h
index 1206449..93ac5d8 100644
--- a/lib/asio_server_http2_handler.h
+++ b/lib/asio_server_http2_handler.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_SERVER_HTTP2_HANDLER_H
 #define ASIO_SERVER_HTTP2_HANDLER_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <map>
 #include <functional>
diff --git a/lib/asio_server_http2_impl.cc b/lib/asio_server_http2_impl.cc
index 00afdd6..981bc00 100644
--- a/lib/asio_server_http2_impl.cc
+++ b/lib/asio_server_http2_impl.cc
@@ -29,7 +29,7 @@
 #include "asio_server.h"
 #include "util.h"
 #include "tls.h"
-#include "template.h"
+#include <nghttp2/template.h>
 
 namespace nghttp2 {
 
diff --git a/lib/asio_server_http2_impl.h b/lib/asio_server_http2_impl.h
index 93a6d2c..519ad8d 100644
--- a/lib/asio_server_http2_impl.h
+++ b/lib/asio_server_http2_impl.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_SERVER_HTTP2_IMPL_H
 #define ASIO_SERVER_HTTP2_IMPL_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_server.h>
 
diff --git a/lib/asio_server_request.cc b/lib/asio_server_request.cc
index 36669a5..8b7db60 100644
--- a/lib/asio_server_request.cc
+++ b/lib/asio_server_request.cc
@@ -22,13 +22,13 @@
  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_server.h>
 
 #include "asio_server_request_impl.h"
 
-#include "template.h"
+#include <nghttp2/template.h>
 
 namespace nghttp2 {
 namespace asio_http2 {
diff --git a/lib/asio_server_request_handler.h b/lib/asio_server_request_handler.h
index 5eefcfd..e57ccfd 100644
--- a/lib/asio_server_request_handler.h
+++ b/lib/asio_server_request_handler.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_SERVER_REQUEST_HANDLER_H
 #define ASIO_SERVER_REQUEST_HANDLER_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_server.h>
 
diff --git a/lib/asio_server_request_impl.h b/lib/asio_server_request_impl.h
index 05de98a..5f83d1a 100644
--- a/lib/asio_server_request_impl.h
+++ b/lib/asio_server_request_impl.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_SERVER_REQUEST_IMPL_H
 #define ASIO_SERVER_REQUEST_IMPL_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_server.h>
 #include <boost/asio/ip/tcp.hpp>
diff --git a/lib/asio_server_response.cc b/lib/asio_server_response.cc
index f67921a..c80769e 100644
--- a/lib/asio_server_response.cc
+++ b/lib/asio_server_response.cc
@@ -22,13 +22,13 @@
  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_server.h>
 
 #include "asio_server_response_impl.h"
 
-#include "template.h"
+#include <nghttp2/template.h>
 
 namespace nghttp2 {
 namespace asio_http2 {
diff --git a/lib/asio_server_response_impl.h b/lib/asio_server_response_impl.h
index 41df7a6..02d8f0e 100644
--- a/lib/asio_server_response_impl.h
+++ b/lib/asio_server_response_impl.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_SERVER_RESPONSE_IMPL_H
 #define ASIO_SERVER_RESPONSE_IMPL_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_server.h>
 
diff --git a/lib/asio_server_serve_mux.h b/lib/asio_server_serve_mux.h
index 017a6bc..73b33bf 100644
--- a/lib/asio_server_serve_mux.h
+++ b/lib/asio_server_serve_mux.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_SERVER_SERVE_MUX_H
 #define ASIO_SERVER_SERVE_MUX_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_server.h>
 
diff --git a/lib/asio_server_stream.h b/lib/asio_server_stream.h
index cd7e081..5014f28 100644
--- a/lib/asio_server_stream.h
+++ b/lib/asio_server_stream.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_SERVER_STREAM_H
 #define ASIO_SERVER_STREAM_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_server.h>
 
diff --git a/lib/asio_server_tls_context.h b/lib/asio_server_tls_context.h
index 0f9b563..f3b8842 100644
--- a/lib/asio_server_tls_context.h
+++ b/lib/asio_server_tls_context.h
@@ -25,7 +25,7 @@
 #ifndef ASIO_SERVER_TLS_CONTEXT_H
 #define ASIO_SERVER_TLS_CONTEXT_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <nghttp2/asio_http2_server.h>
 
diff --git a/lib/http2.h b/lib/http2.h
index 4f0ca5a..a41c0c7 100644
--- a/lib/http2.h
+++ b/lib/http2.h
@@ -25,7 +25,7 @@
 #ifndef HTTP2_H
 #define HTTP2_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <cstdio>
 #include <cstring>
@@ -38,7 +38,7 @@
 #include "url-parser/url_parser.h"
 
 #include "util.h"
-#include "template.h"
+#include <nghttp2/template.h>
 #include "allocator.h"
 
 namespace nghttp2 {
diff --git a/lib/includes/CMakeLists.txt b/lib/includes/CMakeLists.txt
index b4720c6..9e00d12 100644
--- a/lib/includes/CMakeLists.txt
+++ b/lib/includes/CMakeLists.txt
@@ -2,4 +2,7 @@ install(FILES
     nghttp2/asio_http2.h
     nghttp2/asio_http2_client.h
     nghttp2/asio_http2_server.h
+    nghttp2/asio_client_session_impl.h
+    nghttp2/nghttp2_config.h
+    nghttp2/template.h
   DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/nghttp2")
diff --git a/lib/asio_client_session_impl.h b/lib/includes/nghttp2/asio_client_session_impl.h
similarity index 98%
rename from lib/asio_client_session_impl.h
rename to lib/includes/nghttp2/asio_client_session_impl.h
index 694ac20..bddaf81 100644
--- a/lib/asio_client_session_impl.h
+++ b/lib/includes/nghttp2/asio_client_session_impl.h
@@ -25,13 +25,13 @@
 #ifndef ASIO_CLIENT_SESSION_IMPL_H
 #define ASIO_CLIENT_SESSION_IMPL_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <boost/array.hpp>
 
 #include <nghttp2/asio_http2_client.h>
 
-#include "template.h"
+#include <nghttp2/template.h>
 
 namespace nghttp2 {
 namespace asio_http2 {
diff --git a/lib/includes/nghttp2/asio_http2_client.h b/lib/includes/nghttp2/asio_http2_client.h
index 7257914..0179d19 100644
--- a/lib/includes/nghttp2/asio_http2_client.h
+++ b/lib/includes/nghttp2/asio_http2_client.h
@@ -183,6 +183,8 @@ class session {
           const std::string &service,
           const boost::posix_time::time_duration &connect_timeout);
 
+  session(std::shared_ptr<session_impl> impl);
+
   ~session();
 
   session(session &&other) noexcept;
diff --git a/lib/nghttp2_config.h b/lib/includes/nghttp2/nghttp2_config.h
similarity index 100%
rename from lib/nghttp2_config.h
rename to lib/includes/nghttp2/nghttp2_config.h
diff --git a/lib/template.h b/lib/includes/nghttp2/template.h
similarity index 99%
rename from lib/template.h
rename to lib/includes/nghttp2/template.h
index 50ed582..6b8ea3e 100644
--- a/lib/template.h
+++ b/lib/includes/nghttp2/template.h
@@ -25,7 +25,7 @@
 #ifndef TEMPLATE_H
 #define TEMPLATE_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #include <cstring>
 #include <cstdio>
diff --git a/lib/tls.h b/lib/tls.h
index 8b18d32..6db9996 100644
--- a/lib/tls.h
+++ b/lib/tls.h
@@ -25,7 +25,7 @@
 #ifndef TLS_H
 #define TLS_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 namespace nghttp2 {
 
diff --git a/lib/util.h b/lib/util.h
index d980e7a..3e9f757 100644
--- a/lib/util.h
+++ b/lib/util.h
@@ -25,7 +25,7 @@
 #ifndef UTIL_H
 #define UTIL_H
 
-#include "nghttp2_config.h"
+#include <nghttp2/nghttp2_config.h>
 
 #ifdef HAVE_UNISTD_H
 #  include <unistd.h>
@@ -49,7 +49,7 @@
 
 #include "url-parser/url_parser.h"
 
-#include "template.h"
+#include <nghttp2/template.h>
 #include "network.h"
 #include "allocator.h"