Hi: I am writing some serialization code that uses IOStreams as a filter. The following is the class I am trying to serialize. class MIDISurface { public: // surface variables std::wstring strSurfaceName; }; The string header file is included. I then have a template function as follows: template <class SerializingType> void SaveData(SerializingType Data, boost::filesystem::path FileName, bool EncryptData) { //Check file existance. if (boost::filesystem::exists(FileName)) //Delete file boost::filesystem::remove(FileName); //Now create a WOfstream to serialize the data. std::wofstream OutputStream(FileName.generic_wstring()); //Create a filtering_stream to allow us to encrypt the data if necessary. boost::iostreams::wfiltering_stream<boost::iostreams::output> FilteringStream(FileName.generic_wstring()); if (EncryptData) //FilteringStream.push(test); //add the encryption filter defined in Encryption.hpp. FilteringStream.push(OutputStream); boost::archive::xml_woarchive Archive(FilteringStream); //create an archive and assign the filtering stream. Archive << BOOST_SERIALIZATION_NVP(Data); } I am including the following headers. //Standard c++ headers. #include <fstream> #include <stdlib.h> #include <string> #include <boost/iostreams/traits.hpp> //boost filesystem headers. #include <boost/config.hpp> #define BOOST_FILESYSTEM_VERSION 3 #include <boost/filesystem/operations.hpp> #include <boost/filesystem/path.hpp> //Boost xml serialization headers. #include <boost/archive/xml_wiarchive.hpp> #include <boost/archive/xml_woarchive.hpp> //Data type boost serialization headers. #include <boost/config.hpp> #include <boost/serialization/string.hpp> #include <boost/Serialization/Vector.hpp> #include <boost/Serialization/Map.hpp> #include <boost/Serialization/nvp.hpp> //boost io streams header. #include <boost/iostreams/detail/config/wide_streams.hpp> #include <boost/iostreams/concepts.hpp> #include <boost/iostreams/detail/ios.hpp> // BOOST_IOS. #include <boost/iostreams/filter/stdio.hpp> #include <boost/iostreams/operations.hpp> #include <boost/iostreams/filtering_stream.hpp> I am using boost 1.47, from the installer from boost pro computing. Can anyone point in the direction of the solution. Any help appreciated. Sean