Re: iSCSI - revised 2.2.4

[Paul Koning <pkoning@jlc.net>]

Excerpt of message (sent 5 October 2001) by Julian Satran:
> ...
> For numerical and single literal negotiations, the responding party MUST 
> respond with the required key and the value it selects, based on the 
> selection rule specific to the key, becomes the negotiation result. 
> Selection of a value not admissible under the selection rules is 
> considered a protocol error and handled accordingly. 
> 
> For Boolean negotiations (keys taking the values yes or no), the 
> responding party MUST respond with the required key and the result of the 
> negotiation when the received value does not determine that result by 
> itself.  The last value transmitted becomes the negotiation result.  The 
> rules for selecting the value to respond with are expressed as Boolean 
> functions of the value received and the value that the responding party 
> would select in the absence of knowledge of the received value.
>  
> Specifically, the two cases in which responses are OPTIONAL are:
> 
> - The Boolean function is "AND" and the value "no" is received. The 
> outcome of the negotiation is "no".
> - The Boolean function is "OR" and the value "yes" is received. The 
> outcome of the negotiation is "yes".
> 
> Responses are REQUIRED in all other cases, and the value chosen and sent 
> by the responder becomes the outcome of the negotiation.

Julian,

I'm agreeing with Santosh here -- there's extra complexity for the
boolean case that just adds code without any benefit.  More code ==
more bugs.  The rule should be the same for all cases -- responder
sends back the result of the negotiation, always, no exceptions.

That way, the half page of rules quoted above reduces to simply the
following: 

   The responding party MUST respond with the required key and the
   value it selects, based on the selection rule specific to the key,
   becomes the negotiation result.  Selection of a value not
   admissible under the selection rules is considered a protocol error
   and handled accordingly.

No exception cases, no variations for different data types.

   paul