Boost.Serialization with multi thread ... I/O?

text_oarchive constructor has not been completed while receiving of text_iarchive. Are the text_iarchive and text_oarchive sequential?

Official sample of Boost.Asio with Serialization uses stringstream as buffer...
Firstly, text_oarchive binds with ostringstream, and the result of ostringstream::str() is written to ip::tcp::iostream.
Text_iarchive and istringstream, too.

The following code has also not returned from iarchive's construction;

boost::asio::ip::tcp::iostream ios;
boost::archive::text_oarchive(ios);
boost::archive::text_iarchive(ios); // <- It never returns.

What am I wrong ? ... Usage of Boost.Asio ?