What is the difference in this case between SHOULD or MAY?

On Aug 30, 2011, at 2:49 PM, Adam Roach wrote:

> On 8/29/11 9:44 PM, Eric Burger wrote:
>> Yes, and...
>> 
>> I would offer that for most cases, If Y then MUST X or If Z then MUST NOT X 
>> *are* what people usually mean when they say SHOULD.  In the spirit of Say 
>> What You Mean, a bare SHOULD at the very least raise an ID-nit, suggesting 
>> to the author to turn the statement into the if Y then MUST X or if Z then 
>> MUST NOT X form.  Being pedantic and pedagogic:
>>      SHOULD send a 1 UNLESS you receive a 0
>> really means
>>      UNLESS you receive a 0, one MUST send a 1.
>> 
>> My vision of the UNLESS clause is not necessarily a protocol state, but an 
>> environment state.  These are things that I can see fit the SHOULD/UNLESS 
>> form:
>>      SHOULD send a 1 UNLESS you are in a walled garden
>>      SHOULD flip bit 27 UNLESS you have a disk
>>      SHOULD NOT explode UNLESS you are a bomb
>> are all reasonable SHOULD-level statements.
>> 
>> I would offer that ANY construction of SHOULD without an UNLESS is a MAY.
> 
> 
> Eric. Put down the axe and step away from the whetstone. Here, I'll give you 
> some text from RFC 3265 to mull.
> 
> 
>   deactivated: The subscription has been terminated, but the subscriber
>      SHOULD retry immediately with a new subscription.  One primary use
>      of such a status code is to allow migration of subscriptions
>      between nodes.
> 
> 
> Let's examine this use of "SHOULD." If the subscriber doesn't re-subscribe, 
> is it an interop issue? No.
> 
> Is it in the interest of the implementation to re-subscribe? Yes. At least, 
> under most circumstances. Otherwise, they won't get the state change 
> notifications they want.
> 
> Are there cases in which it makes sense for the subscriber _not_ to 
> re-subscribe? Yes, I'm sure there are. It's conceivable that the client 
> happens to be shutting down but hasn't gotten around to terminating this 
> particular subscription yet. But any such exceptions are highly 
> implementation-dependent. Listing them would be useless noise to the reader, 
> and senseless text creation for the author.
> 
> Does "SHOULD" get abused by some authors in some documents? Of course it 
> does. But your crusade to throw out a useful tool just because it has been 
> misused on occasion is an extreme over-reaction. I like this tool. I use this 
> tool. If you see people misusing it, slap them.
> 
> But don't ban the tool.
> 
> /a

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