Re: [ws-tx] Issue 045 - WS-AT: Meaning of "wsp:Optional"

["Monica J. Martin" <Monica.Martin@Sun.COM>]

>malhotra: Although WS-Policy does not define the semantics of missing assertions, it is not
>unreasonable to assume that if a particular policy assertion does not appear, it means
>"don't do that".  For example, if an endpoint does not have a Reliable Messaging
>assertion in its policy it's fair to assume that it does not want a reliable protocol
>used.  And if there is no encryption assertion, this seems to imply that messages 
>shd not be encrypted.
>
>But there are some tricky areas.  For example, if there is no encoding assertion does
>this mean that no encoding shd be used?  It seems to depend on whether the absent
>assertion is among the set of 'known assertions'.
>
>In any case, I think WS-TX is free to adopt the absence-means-don't-do-it semantic
>but it would be good if this was spelt out clearly in the spec.
>
>All the best, Ashok
>
mm1:  This statement from WS-Policy actually does give guidance around 
missing policy assertions, Ashok (as previously stated).

(1) In Section 3.2 of WS-Policy:

..."An assertion whose type is part of the policy's vocabulary but is not included in an alternative is explicitly 
prohibited by the alternative."

Interpretation of the above WS-Policy text indicates that the WS-AT description of the compact shortcut, wsp:Optional="true", has to be the policy alternatives "MUST" and "MUST NOT" rather than the current specified alternatives 
of "MUST" and "SHOULD NOT". Otherwise, WS-AT is misusing WS-Policy....

We should consider both client and server side behavior. For example, 
what happens when the server doesn't recognize the transaction? There is 
a need to clarify and be explicit here.

Thanks.

>>(1) In Section 3.2 of WS-Policy [reference 2]:
>>
>>"An assertion whose type is part of the policy's vocabulary 
>>but is not included in an alternative is explicitly 
>>prohibited by the alternative."
>>
>>Interpretation of the above WS-Policy text indicates that the 
>>WS-AT description of the compact shortcut, 
>>wsp:Optional="true", has to be the policy alternatives "MUST" 
>>and "MUST NOT" rather than the current specified alternatives 
>>of "MUST" and "SHOULD NOT". Otherwise, WS-AT is misusing WS-Policy.
>>