[boost] Serialization and disctintion between eof and end of archive

From: Maciej Sobczak (prog_at_[hidden])
Date: 2006-01-30 03:10:09

Hi,

The boost.serialization library seems to use eod-of-stream in the 
underlying istream object to denote the end-of-archive.

This equivalence might make sense with files where the stream is open 
for a short time and really associated with a single archive, but seems 
to be cumbersome when used with streams that are supposed to be 
long-lived (network sessions?) and used for transmission of many 
separate archives.

The problem arises between two applications that want to use 
serializatioin library for data exchange "on the fly", using network 
sockets. Small tests have shown that it's not enough for the sender to 
flush its output streams (although it does result in the archive's data 
arriving at the destination side). For the archive to be read correctly, 
the sender needs to entirely close the connection. This indicates that 
the end-of-stream condition is used to denote end-of-archive in the 
serialization sense.
Taking into account the interface of the serialization library (where 
the readers are created from streams), where the stream object is 
syntactically supposed to live longer than the archive, treating eof as 
eoa is counterintuitive.
I really expect this to work for the receiver:

std::istream &is = ...; // some input stream, possibly long-lived

while (...)
{
     boost::archive::text_iarchive ar(is);
     // ...
}

with similar structure on the sender-side.

Any thoughts?

-- 
Maciej Sobczak : http://www.msobczak.com/
Programming    : http://www.msobczak.com/prog/