Re: Issue 4262 - Use of wsp:Optional and wsp:Ingorable together - Pro posed Resolution

Hi

"""The WS-Policy Framework allows a policy assertion to be marked with both
"optional" and "Ignorable" simultaneously. The presence of
"@wsp:optional=true" on an assertion is a syntactic compact form for two
alternatives, one with the assertion and the other without the assertion.
Hence syntactically marking an assertion "A" with both the @wsp:Optional and
@wsp:Ignorable with the value of "true" for both, is equivalent to two
alternatives; one where the assertion A exists with @wsp:Ignorable=true and
the second where the assertion A does not exist."""

This contradicts to the primer recommendations where it's recommended that wsp:optional is only used to mark the assertions which the consumer will have to do something about and where it's recommended not to mark such assertions as wsp:ignorable. The proposed text will simply send the confusing message. 

> "@wsp:optional=true" on an assertion is a syntactic compact form

I fully agree. But the group by adopting wsp:ignorable made a clear statement that it's not a syntactic sugar. Otherwise there's no need for wsp:ignorable.

I propose to either prohibit this combination or to update the compact-to-normal form conversion algorithm to put wsp:ignorable assertions into both alternatives due to the fact wsp:optional implies ignorability but wsp:ignorable does not imply optionality as per the spec

Cheers, Sergey

----- Original Message ----- 
From: "Daniel Roth" <Daniel.Roth@microsoft.com>
To: "Prasad Yendluri" <prasad.yendluri@webmethods.com>; <public-ws-policy@w3.org>
Cc: "Asir Vedamuthu" <asirveda@microsoft.com>; <Monica.Martin@Sun.COM>; <Fabian.Ritzmann@Sun.COM>
Sent: Wednesday, March 14, 2007 3:38 AM
Subject: RE: Issue 4262 - Use of wsp:Optional and wsp:Ingorable together - Pro posed Resolution



+1

Daniel Roth

-----Original Message-----
From: Prasad Yendluri [mailto:prasad.yendluri@webmethods.com]
Sent: Tuesday, March 13, 2007 7:34 PM
To: public-ws-policy@w3.org
Cc: Asir Vedamuthu; Monica.Martin@Sun.COM; Daniel Roth; Fabian.Ritzmann@Sun.COM
Subject: Issue 4262 - Use of wsp:Optional and wsp:Ingorable together - Pro posed Resolution

Folks,

Monica, Asir, Dan, Fabian and I agreed to propose the following as the
resolution for this issue
http://www.w3.org/Bugs/Public/show_bug.cgi?id=4262.

1. We now think this issue is actually on the Primer rather than the
Guidelines document, as it is related to composition of a policy expression
(that uses optional and ignorable flags on assertions) rather than design of
assertions.

2. We propose adding the following as a new subsection that follows the
description of the Optional Assertions (section 2.6) and Ignorable
Expressions (Section 2.7), in the Primer.


Updated proposal:
"2.8 Marking Assertions both Optional and Ignorable

As described in the sections above and in Section 3.4.1, WS-Policy 1.5
specification defines two attributes that can be used to mark an assertion:
wsp:Optional and wsp:Ignorable.

The WS-Policy Framework allows a policy assertion to be marked with both
"optional" and "Ignorable" simultaneously. The presence of
"@wsp:optional=true" on an assertion is a syntactic compact form for two
alternatives, one with the assertion and the other without the assertion.
Hence syntactically marking an assertion "A" with both the @wsp:Optional and
@wsp:Ignorable with the value of "true" for both, is equivalent to two
alternatives; one where the assertion A exists with @wsp:Ignorable=true and
the second where the assertion A does not exist.

========
Note: Separately Monica / Fabian plan to address issue of understandability
and mode (?) with Section 3.4.1 and reference back to Section 2.8 if needed.

Thanks,
Prasad