diff --git a/2.0.2/Projects/Simulator/BTM/server_ws.hpp b/2.0.2/Projects/Simulator/BTM/server_ws.hpp
index c508c2f..9ed7a15 100644
--- a/2.0.2/Projects/Simulator/BTM/server_ws.hpp
+++ b/2.0.2/Projects/Simulator/BTM/server_ws.hpp
@@ -5,6 +5,7 @@
 
 #include <boost/asio.hpp>
 #include <boost/asio/spawn.hpp>
+#include <boost/thread/mutex.hpp>
 
 #include <regex>
 #include <unordered_map>
@@ -114,7 +115,8 @@ namespace SimpleWeb {
         
     private:
         std::vector<std::pair<std::regex, Endpoint*> > opt_endpoint;
-        
+		boost::mutex		m_write_mutex;
+
     public:
 
 		void port(uint16_t aPort) {
@@ -157,7 +159,10 @@ namespace SimpleWeb {
         //See http://tools.ietf.org/html/rfc6455#section-5.2 for more information
         void send(std::shared_ptr<Connection> connection, std::shared_ptr<SendStream> send_stream, 
                 const std::function<void(const boost::system::error_code&)>& callback=nullptr, 
-                unsigned char fin_rsv_opcode=129) const {
+                unsigned char fin_rsv_opcode=129)  {
+
+			m_write_mutex.lock();
+
             if(fin_rsv_opcode!=136)
                 timer_idle_reset(connection);
             
@@ -190,24 +195,25 @@ namespace SimpleWeb {
                 //Need to copy the callback-function in case its destroyed
                 boost::system::error_code ec;
                 boost::asio::async_write(*connection->socket, *buffer, yield[ec]);
-                if(ec) {
-                    if(callback)
-                        callback(ec);
-                    return;
-                }
+				if (!ec)
+				{
+					if (send_stream->sending == true)
+						throw std::runtime_error("SendStream already in use! Only reuse a SendStream if you are sure a prior send operation using the stream is finished.");
+
+					send_stream->sending = true;
+					boost::asio::async_write(*connection->socket, send_stream->streambuf, yield[ec]);
+					send_stream->sending = false;
+				}
+
+				m_write_mutex.unlock();
 
-                if(send_stream->sending==true)
-                    throw std::runtime_error("SendStream already in use! Only reuse a SendStream if you are sure a prior send operation using the stream is finished.");
-                send_stream->sending=true;
-                boost::asio::async_write(*connection->socket, send_stream->streambuf, yield[ec]);
-                send_stream->sending=false;
                 if(callback)
                     callback(ec);
             });
         }
         
         
-        void send_close(std::shared_ptr<Connection> connection, int status, const std::string& reason="") const {
+        void send_close(std::shared_ptr<Connection> connection, int status, const std::string& reason="") {
             //Send close only once (in case close is initiated by server)
             if(connection->closed.load()) {
                 return;
@@ -377,7 +383,7 @@ namespace SimpleWeb {
         }
         
         void read_message(std::shared_ptr<Connection> connection, 
-                std::shared_ptr<boost::asio::streambuf> read_buffer, Endpoint& endpoint) const {
+                std::shared_ptr<boost::asio::streambuf> read_buffer, Endpoint& endpoint) {
             boost::asio::async_read(*connection->socket, *read_buffer, boost::asio::transfer_exactly(2),
                     [this, connection, read_buffer, &endpoint]
                     (const boost::system::error_code& ec, size_t bytes_transferred) {
@@ -456,7 +462,7 @@ namespace SimpleWeb {
         
         void read_message_content(std::shared_ptr<Connection> connection, 
                 std::shared_ptr<boost::asio::streambuf> read_buffer, 
-                size_t length, Endpoint& endpoint, unsigned char fin_rsv_opcode) const {
+                size_t length, Endpoint& endpoint, unsigned char fin_rsv_opcode) {
             boost::asio::async_read(*connection->socket, *read_buffer, boost::asio::transfer_exactly(4+length),
                     [this, connection, read_buffer, length, &endpoint, fin_rsv_opcode]
                     (const boost::system::error_code& ec, size_t bytes_transferred) {
@@ -554,7 +560,7 @@ namespace SimpleWeb {
                 timer_idle_expired_function(connection);
             }
         }
-        void timer_idle_reset(std::shared_ptr<Connection> connection) const {
+        void timer_idle_reset(std::shared_ptr<Connection> connection) {
             if(timeout_idle>0 && connection->timer_idle->expires_from_now(boost::posix_time::seconds(timeout_idle))>0) {
                 timer_idle_expired_function(connection);
             }
@@ -564,7 +570,7 @@ namespace SimpleWeb {
                 connection->timer_idle->cancel();
         }
         
-        void timer_idle_expired_function(std::shared_ptr<Connection> connection) const {
+        void timer_idle_expired_function(std::shared_ptr<Connection> connection) {
             connection->timer_idle->async_wait([this, connection](const boost::system::error_code& ec){
                 if(!ec) {
                     //1000=normal closure