[librsync-devel] Re: state of the rsync nation? (revisited 6/2003 from 11/2000)

Martin Pool mbp at samba.org
Fri Jun 13 13:25:06 EST 2003

On 12 Jun 2003, jw schultz <jw at pegasys.ws> wrote:

> Leave the communications protocol to the communications
> layer.  You don't save anything by coding reordering and
> retransmission at the packet level; that is infrastructure.
> Connectionless is fine.  Lightweight sessions is better.  If
> you lose a connection a restart is possible.  It is
> preferable to not have to authenticate and negotiate
> protocol versions and encryption with every message.
> Think in terms of transactions.  Each transaction is atomic.
> If a transaction doesn't complete you have the means to
> roll-back and retry.  If a connection breaks between
> transactions, or leaving a transaction incomplete, you start
> a new connection and pick up where you left off.

I agree with all this.

To extend on what jw says:

I think it's fine to (if desired) negotiate SSL, authentication, and
compression at the start of a connection.  They generally require
multiple round trips and it would be wasteful to do them more
frequently when per-connection is natural.

On the other hand it would be nice if the client could pick up an
interrupted transfer halfway through the tree, rather than needing to
start from the beginning as rsync 2.x does. 


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