Jonathan Bishop:

HI, I am involved in a project which requires the transport of large C++ instances over MPI communication channels. I am using boost serialization to pack and unpack the objects into a buffer. The whole buffer is sent in one shot.

Of course for large objects this can be problematic. I have two questions...

1) is there any way to tell beforehand how large the buffer needs to be? In other words, can you run serialization in a counting only mode?

I'm not sure about the Boost Serialization library, but the C++ Middleware Writer counts the number of bytes in a message before any is marshalled. Here's an example void remote_messages::Marshal (SendCompressedBuffer& buf , marshalling_integer const& abt1 , marshalling_integer const& abt2 , cmw_user_input const& abt3 ) { Counter cntr(msg_length_max); abt1.CalculateMarshallingSize(cntr); abt2.CalculateMarshallingSize(cntr); abt3.CalculateMarshallingSize(cntr); cntr.Add(sizeof(msg_id_direct)); buf.Receive(&msg_id_direct, sizeof(msg_id_direct)); abt1.Marshal(buf, false); abt2.Marshal(buf, false); abt3.Marshal(buf, false); } -- Brian Wood Ebenezer Enterprises http://webEbenezer.net http://webebenezer.net/