[Bug 3789] Clarify usage of assertions with no behavioral requirements on the requester

http://www.w3.org/Bugs/Public/show_bug.cgi?id=3789

           Summary: Clarify usage of assertions with no behavioral
                    requirements on the requester
           Product: WS-Policy
           Version: PR
          Platform: PC
        OS/Version: Windows XP
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Framework
        AssignedTo: sergey.beryozkin@iona.com
        ReportedBy: sergey.beryozkin@iona.com
         QAContact: public-ws-policy-qa@w3.org
                CC: william.henry@iona.com


Target : WS-Policy Framework and policy guidelines

Justification :

There's a class of policy assertions which have no behavioral requirements on
the requester but can be still usefully processed by requesters which are aware
of what assertions mean. 
For example : <oasis:Replicatable/>

An assertion like this one can be a useful source of information for
requesters. Providers having expected properties like <oasis:Replicatable/> can
be chosen/searched. 
At the same time, given the fact assertions like <oasis:Replicatable/>
have no behavioral requirements on the provider it's important to ensure 
policy-aware clients which have no knowledge of these assertions can proceed
consuming the service advertsing this assertion.

Currently the way to advertise such an assertion is to use a normal form with
two policy alternatives(simple case), with only one alternative containing this
assertion thus making it optional, or, in other words, giving a chance to
requesters to ignore it.
Such normal form expression is equivalent to a compact form with the optional
assertion marked with wsp:optional attribute with a value 'true'.

However, at the moment the primer recommends using wsp:optional when one needs
to mark asssertions which identify optional capabilities/requirements with
behavioral requirements on a requester should the requester wishes to use it. 

Thus marking assertions like <oasis:Replicatable/> with wsp:optional is
considered to be a wrong approach.

Proposal : 

Clarify the text describing the optionality in the policy guidelines and in the
Framework spec on how a policy author should use assertions like
<oasis:Replicatable/>.
It's important that assertions like these can be usefully interpreted by
knowledgeble requesters and safely ignored by requesters unaware of them.

Received on Tuesday, 3 October 2006 21:34:57 UTC