[Boost-users] Different behavior of boost::serialization of strings on text archive

Subject: [Boost-users] Different behavior of boost::serialization of strings on text archive
From: Andrea Ranieri (andreran_at_[hidden])
Date: 2013-07-03 06:25:26

Hi all,

I'm having some issue serializing a `std::string` with
`boost::serialization` on a `text_oarchive`. AFAICT, I have two identical
pieces of code that behaves differently in two different programs.

This is the program that I believe is behaving correctly:

    #include <iostream>
    #include <string>
    #include <sstream>

    #include <boost/archive/text_iarchive.hpp>
    #include <boost/archive/text_oarchive.hpp>

    template <typename T>
    void serialize_deserialize(const T & src, T & dst)
    {
        std::string serialized_data_str;

        std::cout << "original data: " << src << std::endl;

        std::ostringstream archive_ostream;
        boost::archive::text_oarchive oarchive(archive_ostream);
        oarchive << src;
        serialized_data_str = archive_ostream.str();
        std::cout << "serialized data: " << serialized_data_str <<
std::endl;

        std::istringstream archive_istream(serialized_data_str);
        boost::archive::text_iarchive iarchive(archive_istream);
        iarchive >> dst;
    }

    int main()
    {
        std::string archived_data_str = "abcd";
        std::string restored_data_str;

        serialize_deserialize<std::string>(archived_data_str,
restored_data_str);

        std::cout << "restored data: " << restored_data_str << std::endl;

        return 0;
    }

And this is its output:

    original data: abcd
    serialized data: 22 serialization::archive 10 4 abcd
    restored data: abcd

(You can compile it with: `g++ boost-serialization-string.cpp -o
boost-serialization-string -lboost_serialization`)

This one, on the other hand, is an excerpt of the program I'm writing
(derived from [boost_asio/example/serialization/connection.hpp][1]) that
serializes `std::string` data converting each character in its hex
representation:

    /// Asynchronously write a data structure to the socket.
    template <typename T, typename Handler>
    void async_write(const T& t, Handler handler)
    {
      // Serialize the data first so we know how large it is.
      std::cout << "original data: " << t << std::endl;
      std::ostringstream archive_stream;
      boost::archive::text_oarchive archive(archive_stream);
      archive << t;
      outbound_data_ = archive_stream.str();
      std::cout << "serialized data: " << outbound_data_ << std::endl;
      [...]

And this is an excerpt of its output:

    original data: abcd
    serialized data: 22 serialization::archive 10 5 97 98 99 100 0

The version (`10`) is the same, right? So that should be the proof that I'm
using the same serialization library in both programs.

However, I really can't figure out what's going on here. I've been trying
to solve this puzzle for almost an entire work day now, and I'm out of
ideas.

For anyone that may want to reproduce this result, it should be sufficient
to download the [Boost serialization example][2], add the following line

    connection_.async_write("abcd", boost::bind(&client::handle_write,
this, boost::asio::placeholders::error));

at line 50 of `client.cpp`, add the following member function in client.cpp

    /// Handle completion of a write operation.
    void handle_write(const boost::system::error_code& e)
    {
      // Nothing to do. The socket will be closed automatically when the
last
      // reference to the connection object goes away.
    }

add this `cout`:

    std::cout << "serialized data: " << outbound_data_ << std::endl;

at `connection.hpp:59`

and compile with:

    g++ -O0 -g3 client.cpp -o client -lboost_serialization -lboost_system
    g++ -O0 -g3 server.cpp -o server -lboost_serialization -lboost_system

I'm using `g++ 4.8.1` under `Ubuntu 13.04 64bit` with `Boost 1.53`

Any help would be greatly appreciated.

Best regards
Avio

P.s. I'm posting this because the deserialization of the `std::string`s
isn't working at all! :)

  [1]:
http://www.boost.org/doc/libs/1_53_0/doc/html/boost_asio/example/serialization/connection.hpp
  [2]:
http://www.boost.org/doc/libs/1_53_0/doc/html/boost_asio/examples.html#boost_asio.examples.serialization