[boost] asio formal review

From: Eugene Alterman (eugalt_at_[hidden])
Date: 2005-12-11 20:55:58

At last!
A networking library in the true spirit of Boost.

I have a few thoughts regarding the design that is basically a follow-up to 
the discussion started in the asio-users mailing list:
http://sourceforge.net/mailarchive/forum.php?thread_id=9196138&forum_id=42787

The library documents a Stream conecpt that represent a read/write stream 
interface over a connection. In addition to this interface classes that 
implement Stream contain methods for supporting establishment and management 
of the stream's underlying infrastructure - active and passive connection 
establishment, accessing socket options, handshakimg etc.
I suggest to decouple this functionality from the Stream  into a separate 
concept/interface for all the activities leading to the establishment of a 
stream as well as accessing connection properties. This IMO would lead to a 
more flexible and cleaner design.

Streams could be layered (eg. SSL/TLS over TCP), and stream layering should 
be strictly enforced. Once the top level stream has been established there 
should be no access to lower level streams. When you have an established 
secure connection you don't want to allow direct read/write on the 
underlying TCP socket.

Take a look at the Stream doc and notice the lowest_layer() public member 
function that exposes a lower layer stream. Interestinlgly, this method is 
not related to the documented stream functionality. It is used for 
connection establishemnt and accessing connection properties.

The bottom line of my suggestion is to have 2 distinct interfaces. One is 
for stream establishment and connection properties management. It provides 
efficient protocol stack layer navigation and access (but no stream i/o 
operations). The other one is strictly layered streaming interface for data 
transfer.

Do you think it makes sense?

Thank you,
Eugene