diff --git a/test_client/async_client.hpp b/test_client/async_client.hpp
index 3b55aca..8640c64 100644
--- a/test_client/async_client.hpp
+++ b/test_client/async_client.hpp
@@ -1,6 +1,8 @@
 #pragma once
 #include <string>
+#include <deque>
 #include <boost/asio.hpp>
+#include <boost/bind.hpp>
 using boost::asio::ip::tcp;
 #include "../codec.h"
 using namespace rest_rpc;
@@ -8,7 +10,7 @@ using namespace rest_rpc::rpc_service;
 
 class async_client : private boost::noncopyable {
 public:
-	async_client(const std::string& host, unsigned short port) : socket_(ios_), work_(ios_), 
+	async_client(const std::string& host, unsigned short port) : socket_(ios_), work_(ios_), strand_(ios_),
 		deadline_(ios_), host_(host), port_(port) {
 		thd_ = std::make_shared<std::thread>([this] {
 			ios_.run();
@@ -20,7 +22,7 @@ public:
 	}
 
 	void set_connect_timeout(size_t seconds) {
-		timeout_ = seconds;
+		connect_timeout_ = seconds;
 	}
 
 	void set_reconnect_count(int reconnect_count) {
@@ -28,7 +30,7 @@ public:
 	}
 
 	void connect() {
-		reset_connect_timer();
+		reset_deadline_timer(connect_timeout_);
 		auto addr = boost::asio::ip::make_address_v4(host_);
 		socket_.async_connect({ addr, port_ }, [this](const boost::system::error_code& ec) {
 			if (ec) {
@@ -53,6 +55,19 @@ public:
 		});
 	}
 
+	void write(std::string&& message)
+	{
+		strand_.post([this, msg = std::move(message)] {
+			outbox_.emplace_back(std::move(msg));
+			if (outbox_.size() > 1) {
+				// outstanding async_write
+				return;
+			}
+
+			this->write();
+		});
+	}
+
 	bool has_connected() const {
 		return has_connected_;
 	}
@@ -66,8 +81,8 @@ public:
 	}
 
 private:
-	void reset_connect_timer() {
-		deadline_.expires_from_now(boost::posix_time::seconds((long)timeout_));
+	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) {
 			if (!ec) {
 				socket_.close();
@@ -75,16 +90,39 @@ private:
 		});
 	}
 
+	void write()
+	{
+		const std::string& message = outbox_[0];
+		boost::asio::async_write(socket_,boost::asio::buffer(message.c_str(), message.size()),
+			strand_.wrap([this](const boost::system::error_code& ec, const size_t bytesTransferred) {
+				outbox_.pop_front();
+
+				if (ec) {
+					std::cerr << "could not write: " << ec.message() << std::endl;
+					return;
+				}
+
+				if (!outbox_.empty()) {
+					// more messages to send
+					this->write();
+				}
+			})
+		);
+	}
+
 	bool has_connected_ = false;
 	boost::asio::io_service ios_;
 	tcp::socket socket_;
 	boost::asio::io_service::work work_;
+	boost::asio::io_service::strand strand_;
 	std::shared_ptr<std::thread> thd_ = nullptr;
 
 	std::string host_;
 	unsigned short port_;
-	int timeout_=1;//s
+	size_t connect_timeout_  = 1;//s
 	int reconnect_cnt_ = -1;
 
 	boost::asio::deadline_timer deadline_;
+
+	std::deque<std::string> outbox_;
 };
\ No newline at end of file