Re: OT: Re: Less is more

[Keith Moore <moore@xxxxxxxxxx>]

> 
> On Wed, 5 May 2004 06:02, Keith Moore wrote:
> > the job of the submission agent is to authenticate the source (for
> > some meaning of "authenticate", to reject or fix invalid messages
> > (and provide feedback to the user that his MUA is broken) and submit
> > valid messages to the email transport system.
> 
> My earlier point still holds. Regardless of whether or not a client is
> acting in the "submission" role or the "relay" role, it may or may not
> be violating protocol somewhere in the transaction. 

a relay is not violating protocol if it passes on the content it
receives intact, because the protocol should explicitly specify 
that a relay works that way. 

> If a server performs strict protocol 
> checks at every stage of the dialogue, then it will reject such
> violations; if it assumes that the client observes protocol correctly,
> then it will propagate violations.

performing strict checking at every stage of the dialogue is a layering
violation - and it results in degraded interoperability due to server 
implementation errors and variations in interpretation. 

> To put it another way, it's the client's job to pass on data only in a
> way that observes protocol, but can the server assume the client is
> doing its job? 

if the protocol is defined to work that way, yes.  and a sound protocol
architecture is one that has a clean separation of function, not one
where every component tries to second-guess every other component.

> This seems to be largely a question of implementation.

nope, it's a question of design and architecture.

--
Regime change 2004 - better late than never.