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serialization/connection.hpp

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00001 //
00002 // connection.hpp
00003 // ~~~~~~~~~~~~~~
00004 //
00005 // Copyright (c) 2003-2007 Christopher M. Kohlhoff (chris at kohlhoff dot com)
00006 //
00007 // Distributed under the Boost Software License, Version 1.0. (See accompanying
00008 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
00009 //
00010 
00011 #ifndef SERIALIZATION_CONNECTION_HPP
00012 #define SERIALIZATION_CONNECTION_HPP
00013 
00014 #include <asio.hpp>
00015 #include <boost/archive/text_iarchive.hpp>
00016 #include <boost/archive/text_oarchive.hpp>
00017 #include <boost/bind.hpp>
00018 #include <boost/shared_ptr.hpp>
00019 #include <boost/tuple/tuple.hpp>
00020 #include <iomanip>
00021 #include <string>
00022 #include <sstream>
00023 #include <vector>
00024 
00025 namespace s11n_example {
00026 
00028 
00034 class connection
00035 {
00036 public:
00038   connection(asio::io_service& io_service)
00039     : socket_(io_service)
00040   {
00041   }
00042 
00045   asio::ip::tcp::socket& socket()
00046   {
00047     return socket_;
00048   }
00049 
00051   template <typename T, typename Handler>
00052   void async_write(const T& t, Handler handler)
00053   {
00054     // Serialize the data first so we know how large it is.
00055     std::ostringstream archive_stream;
00056     boost::archive::text_oarchive archive(archive_stream);
00057     archive << t;
00058     outbound_data_ = archive_stream.str();
00059 
00060     // Format the header.
00061     std::ostringstream header_stream;
00062     header_stream << std::setw(header_length)
00063       << std::hex << outbound_data_.size();
00064     if (!header_stream || header_stream.str().size() != header_length)
00065     {
00066       // Something went wrong, inform the caller.
00067       asio::error_code error(asio::error::invalid_argument);
00068       socket_.io_service().post(boost::bind(handler, error));
00069       return;
00070     }
00071     outbound_header_ = header_stream.str();
00072 
00073     // Write the serialized data to the socket. We use "gather-write" to send
00074     // both the header and the data in a single write operation.
00075     std::vector<asio::const_buffer> buffers;
00076     buffers.push_back(asio::buffer(outbound_header_));
00077     buffers.push_back(asio::buffer(outbound_data_));
00078     asio::async_write(socket_, buffers, handler);
00079   }
00080 
00082   template <typename T, typename Handler>
00083   void async_read(T& t, Handler handler)
00084   {
00085     // Issue a read operation to read exactly the number of bytes in a header.
00086     void (connection::*f)(
00087         const asio::error_code&,
00088         T&, boost::tuple<Handler>)
00089       = &connection::handle_read_header<T, Handler>;
00090     asio::async_read(socket_, asio::buffer(inbound_header_),
00091         boost::bind(f,
00092           this, asio::placeholders::error, boost::ref(t),
00093           boost::make_tuple(handler)));
00094   }
00095 
00099   template <typename T, typename Handler>
00100   void handle_read_header(const asio::error_code& e,
00101       T& t, boost::tuple<Handler> handler)
00102   {
00103     if (e)
00104     {
00105       boost::get<0>(handler)(e);
00106     }
00107     else
00108     {
00109       // Determine the length of the serialized data.
00110       std::istringstream is(std::string(inbound_header_, header_length));
00111       std::size_t inbound_data_size = 0;
00112       if (!(is >> std::hex >> inbound_data_size))
00113       {
00114         // Header doesn't seem to be valid. Inform the caller.
00115         asio::error_code error(asio::error::invalid_argument);
00116         boost::get<0>(handler)(error);
00117         return;
00118       }
00119 
00120       // Start an asynchronous call to receive the data.
00121       inbound_data_.resize(inbound_data_size);
00122       void (connection::*f)(
00123           const asio::error_code&,
00124           T&, boost::tuple<Handler>)
00125         = &connection::handle_read_data<T, Handler>;
00126       asio::async_read(socket_, asio::buffer(inbound_data_),
00127         boost::bind(f, this,
00128           asio::placeholders::error, boost::ref(t), handler));
00129     }
00130   }
00131 
00133   template <typename T, typename Handler>
00134   void handle_read_data(const asio::error_code& e,
00135       T& t, boost::tuple<Handler> handler)
00136   {
00137     if (e)
00138     {
00139       boost::get<0>(handler)(e);
00140     }
00141     else
00142     {
00143       // Extract the data structure from the data just received.
00144       try
00145       {
00146         std::string archive_data(&inbound_data_[0], inbound_data_.size());
00147         std::istringstream archive_stream(archive_data);
00148         boost::archive::text_iarchive archive(archive_stream);
00149         archive >> t;
00150       }
00151       catch (std::exception& e)
00152       {
00153         // Unable to decode data.
00154         asio::error_code error(asio::error::invalid_argument);
00155         boost::get<0>(handler)(error);
00156         return;
00157       }
00158 
00159       // Inform caller that data has been received ok.
00160       boost::get<0>(handler)(e);
00161     }
00162   }
00163 
00164 private:
00166   asio::ip::tcp::socket socket_;
00167 
00169   enum { header_length = 8 };
00170 
00172   std::string outbound_header_;
00173 
00175   std::string outbound_data_;
00176 
00178   char inbound_header_[header_length];
00179 
00181   std::vector<char> inbound_data_;
00182 };
00183 
00184 typedef boost::shared_ptr<connection> connection_ptr;
00185 
00186 } // namespace s11n_example
00187 
00188 #endif // SERIALIZATION_CONNECTION_HPP
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