diff --git a/examples/client/CMakeLists.txt b/examples/client/CMakeLists.txt
index e449365..e45eb43 100644
--- a/examples/client/CMakeLists.txt
+++ b/examples/client/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.7)
 project(basic_client)
 
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthread -std=c++17")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthread -std=c++11")
 
 find_package(Boost COMPONENTS system REQUIRED)
 include_directories(
diff --git a/examples/client/basic_client.vcxproj b/examples/client/basic_client.vcxproj
index 02aba23..1af657f 100644
--- a/examples/client/basic_client.vcxproj
+++ b/examples/client/basic_client.vcxproj
@@ -87,7 +87,6 @@
       <Optimization>Disabled</Optimization>
       <SDLCheck>true</SDLCheck>
       <ConformanceMode>true</ConformanceMode>
-      <LanguageStandard>stdcpp17</LanguageStandard>
       <DisableSpecificWarnings>4996</DisableSpecificWarnings>
     </ClCompile>
   </ItemDefinitionGroup>
@@ -97,7 +96,6 @@
       <Optimization>Disabled</Optimization>
       <SDLCheck>true</SDLCheck>
       <ConformanceMode>true</ConformanceMode>
-      <LanguageStandard>stdcpp17</LanguageStandard>
       <DisableSpecificWarnings>4996</DisableSpecificWarnings>
     </ClCompile>
   </ItemDefinitionGroup>
@@ -109,7 +107,6 @@
       <IntrinsicFunctions>true</IntrinsicFunctions>
       <SDLCheck>true</SDLCheck>
       <ConformanceMode>true</ConformanceMode>
-      <LanguageStandard>stdcpp17</LanguageStandard>
       <DisableSpecificWarnings>4996</DisableSpecificWarnings>
     </ClCompile>
     <Link>
@@ -125,7 +122,6 @@
       <IntrinsicFunctions>true</IntrinsicFunctions>
       <SDLCheck>true</SDLCheck>
       <ConformanceMode>true</ConformanceMode>
-      <LanguageStandard>stdcpp17</LanguageStandard>
       <DisableSpecificWarnings>4996</DisableSpecificWarnings>
     </ClCompile>
     <Link>
diff --git a/examples/client/main.cpp b/examples/client/main.cpp
index 2382654..315dac3 100644
--- a/examples/client/main.cpp
+++ b/examples/client/main.cpp
@@ -256,7 +256,6 @@ void test_performance2() {
 }
 
 int main() {
-	test_performance1();
 	test_sync_client();
 	test_async_client();
 	//test_upload();
diff --git a/examples/server/CMakeLists.txt b/examples/server/CMakeLists.txt
index 79171d6..4e5d730 100644
--- a/examples/server/CMakeLists.txt
+++ b/examples/server/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.7)
 project(basic_server)
 
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthread -std=c++17")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthread -std=c++11")
 
 find_package(Boost COMPONENTS system REQUIRED)
 include_directories(
diff --git a/examples/server/basic_server.vcxproj b/examples/server/basic_server.vcxproj
index 999f4af..58a393d 100644
--- a/examples/server/basic_server.vcxproj
+++ b/examples/server/basic_server.vcxproj
@@ -87,7 +87,6 @@
       <Optimization>Disabled</Optimization>
       <SDLCheck>true</SDLCheck>
       <ConformanceMode>true</ConformanceMode>
-      <LanguageStandard>stdcpp17</LanguageStandard>
       <DisableSpecificWarnings>4996</DisableSpecificWarnings>
     </ClCompile>
   </ItemDefinitionGroup>
@@ -97,7 +96,6 @@
       <Optimization>Disabled</Optimization>
       <SDLCheck>true</SDLCheck>
       <ConformanceMode>true</ConformanceMode>
-      <LanguageStandard>stdcpp17</LanguageStandard>
       <DisableSpecificWarnings>4996</DisableSpecificWarnings>
     </ClCompile>
   </ItemDefinitionGroup>
@@ -109,7 +107,6 @@
       <IntrinsicFunctions>true</IntrinsicFunctions>
       <SDLCheck>true</SDLCheck>
       <ConformanceMode>true</ConformanceMode>
-      <LanguageStandard>stdcpp17</LanguageStandard>
       <DisableSpecificWarnings>4996</DisableSpecificWarnings>
     </ClCompile>
     <Link>
@@ -125,7 +122,6 @@
       <IntrinsicFunctions>true</IntrinsicFunctions>
       <SDLCheck>true</SDLCheck>
       <ConformanceMode>true</ConformanceMode>
-      <LanguageStandard>stdcpp17</LanguageStandard>
       <DisableSpecificWarnings>4996</DisableSpecificWarnings>
     </ClCompile>
     <Link>
diff --git a/examples/server/main.cpp b/examples/server/main.cpp
index 49bfe95..acd9ac9 100644
--- a/examples/server/main.cpp
+++ b/examples/server/main.cpp
@@ -68,7 +68,7 @@ std::string get_name(connection* conn, const person& p) {
 }
 
 int main() {
-	rpc_server server(9000, 4);
+	rpc_server server(9000, std::thread::hardware_concurrency());
 
 	dummy d;
 	server.register_handler("add", &dummy::add, &d);
diff --git a/include/client_util.hpp b/include/client_util.hpp
index b3d236c..44cdcf8 100644
--- a/include/client_util.hpp
+++ b/include/client_util.hpp
@@ -1,9 +1,16 @@
 #pragma once
+#include <tuple>
+#if __cplusplus > 201402L
 #include <string_view>
+using string_view = std::string_view;
+#else
+#include <boost/utility/string_view.hpp>
+using string_view = boost::string_view;
+#endif
 #include "codec.h"
 
 namespace rest_rpc {
-	inline bool has_error(std::string_view result) {
+	inline bool has_error(string_view result) {
 		rpc_service::msgpack_codec codec;
 		auto tp = codec.unpack<std::tuple<int>>(result.data(), result.size());
 
@@ -11,7 +18,7 @@ namespace rest_rpc {
 	}
 
 	template<typename T>
-	inline T get_result(std::string_view result) {
+	inline T get_result(string_view result) {
 		rpc_service::msgpack_codec codec;
 		auto tp = codec.unpack<std::tuple<int>>(result.data(), result.size());
 		if (std::get<0>(tp) != 0) {
diff --git a/include/cplusplus_14.h b/include/cplusplus_14.h
index 487ced7..a72592a 100644
--- a/include/cplusplus_14.h
+++ b/include/cplusplus_14.h
@@ -1,6 +1,9 @@
 #ifndef REST_RPC_CPLUSPLUS_14_H_
 #define REST_RPC_CPLUSPLUS_14_H_
 
+#include <type_traits>
+#include <memory>
+
 #if __cplusplus == 201103L
 
 namespace std {
diff --git a/include/rpc_client.hpp b/include/rpc_client.hpp
index 35f6b1d..bd89bbf 100644
--- a/include/rpc_client.hpp
+++ b/include/rpc_client.hpp
@@ -18,7 +18,7 @@ namespace rest_rpc {
 	class req_result {
 	public:
 		req_result() = default;
-		req_result(std::string_view data) : data_(data) {}
+		req_result(string_view data) : data_(data) {}
 		bool success() const {
 			return !has_error(data_);
 		}
@@ -34,7 +34,7 @@ namespace rest_rpc {
 			}
 		}
 	private:
-		std::string_view data_;
+		string_view data_;
 	};
 
 	class rpc_client : private boost::noncopyable {
@@ -99,7 +99,7 @@ namespace rest_rpc {
 				return true;
 			}
 
-			std::unique_lock lock(conn_mtx_);
+			std::unique_lock<std::mutex> lock(conn_mtx_);
 			bool result = conn_cond_.wait_for(lock, std::chrono::seconds(timeout),
 				[this] {return has_connected_; });
 			return result;
@@ -110,8 +110,9 @@ namespace rest_rpc {
 		}
 
 		//sync call
+#if __cplusplus > 201402L
 		template<typename T = void, typename... Args>
-		auto call(const std::string& rpc_name, Args&&... args) {
+		auto call(const std::string& rpc_name, Args&& ... args) {
 			std::future<req_result> future = async_call(rpc_name, std::forward<Args>(args)...);
 			auto status = future.wait_for(std::chrono::seconds(1));
 			if (status == std::future_status::timeout || status == std::future_status::deferred) {
@@ -125,6 +126,29 @@ namespace rest_rpc {
 				return future.get().as<T>();
 			}
 		}
+#else
+		template<typename T=void, typename... Args>
+		typename std::enable_if<std::is_void<T>::value>::type call(const std::string& rpc_name, Args&& ... args) {
+			std::future<req_result> future = async_call(rpc_name, std::forward<Args>(args)...);
+			auto status = future.wait_for(std::chrono::seconds(1));
+			if (status == std::future_status::timeout || status == std::future_status::deferred) {
+				throw std::out_of_range("timeout or deferred");
+			}
+
+			future.get().as();
+		}
+
+		template<typename T, typename... Args>
+		typename std::enable_if<!std::is_void<T>::value, T>::type call(const std::string& rpc_name, Args&& ... args) {
+			std::future<req_result> future = async_call(rpc_name, std::forward<Args>(args)...);
+			auto status = future.wait_for(std::chrono::seconds(1));
+			if (status == std::future_status::timeout || status == std::future_status::deferred) {
+				throw std::out_of_range("timeout or deferred");
+			}
+
+			return future.get().as<T>();
+		}
+#endif
 
 		template<typename... Args>
 		auto async_call(const std::string& rpc_name, Args&&... args) {
@@ -149,7 +173,7 @@ namespace rest_rpc {
 		}
 
 	private:
-		using message_type = std::pair<std::string_view, std::uint64_t>;
+		using message_type = std::pair<string_view, std::uint64_t>;
 		void reset_deadline_timer(size_t timeout) {
 			deadline_.expires_from_now(boost::posix_time::seconds((long)timeout));
 			deadline_.async_wait([this](const boost::system::error_code& ec) {
@@ -260,14 +284,14 @@ namespace rest_rpc {
 		std::future<req_result> get_future() {
 			auto p = std::make_shared<std::promise<req_result>>();
 			
-			std::future future = p->get_future();
+			std::future<req_result> future = p->get_future();
 			strand_.post([this, p1 = std::move(p)] () mutable { 
 				future_map_.emplace(req_id_, std::move(p1)); 
 			});
 			return future;
 		}
 
-		void call_back(uint64_t req_id, const boost::system::error_code& ec, std::string_view data) {
+		void call_back(uint64_t req_id, const boost::system::error_code& ec, string_view data) {
 			if (ec) {
 				//LOG<<ec.message();
 			}