Re: [Bug 8286] New: description of Subscription End ambiguous

I agree that saying "MUST", then trying to hedge it with a "unless the 
event source is incapable of transmitting any messages at all" is ill 
advised. If your impl is incapable of sending any messages at all 
something is broken (e.g. your network, your code, whatever) and any 
claim of compliance with WS-Eventing is pretty much moot at that point.

I would prefer simply:

"If the event source terminates a subscription unexpectedly and the
wse:EndTo EPR was present in the Subscribe message for that subscription
(see 4.1 Subscribe), the SubscriptionEnd message MUST be sent to the
endpoint referenced by that EPR."

- gp

On 1/12/2010 7:43 AM, Li, Li (Li) wrote:
> Eventing Current text:
> If the event source terminates a subscription unexpectedly, a
> SubscriptionEnd SOAP message SHOULD be sent to the endpoint reference
> indicated when the subscription was created (see 4.1 Subscribe). This
> endpoint reference MUST refer to an endpoint that supports the
> SubscriptionEndPortType portType.
>
> Proposal:
> If the event source terminates a subscription unexpectedly and the
> wse:EndTo EPR was present in the Subscribe message for that subscription
> (see 4.1 Subscribe), the SubscriptionEnd message MUST be sent to the
> endpoint referenced by that EPR unless the event source is incapable of
> transmitting any messages at all. 
>
> I understand that the proposed change is to narrow the scope of
> exception to the requirement. However, I also feel that MUST + exception
> = SHOULD. 
>
> I think MUST always means "absolute requirement" which may not be
> achieved by a conformant implementation due to unforeseen situations. 
>
> If we adopt the proposal, should we also check exceptions to all MUST?
> For example, the (unless .... incapable ...) seems applicable to the
> following requirement in WS-E 4.1 as well:
>
> [Body]/wse:Subscribe/wse:Delivery/wse:NotifyTo 
> This is an OPTIONAL element. When present, this element indicates that
> notifications MUST be sent to the EndpointReference identified by this
> element. 
>
> I think it's better to just say MUST without any exception, or use
> SHOULD, but not the mixed.
>
> Thanks.
>
> Li
>
>
>