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Subject: [NEW ISSUE] Calculation of the Required Intent Set for an Element has aFlaw
- From: Mike Edwards <mike_edwards@uk.ibm.com>
- To: "OASIS Policy" <sca-policy@lists.oasis-open.org>
- Date: Fri, 26 Jun 2009 09:40:42 +0100
Raiser:
Mike Edwards
Target:
CD02 of the Policy Spec: sca-policy-1.1-spec-cd02.pdf
Description:
** Raised as a result of an action item
from the SCA Bindings TC ***
In Section 4.12.1 of the Policy spec,
there is a definition of the required intent set for
an element
This definition has a flaw that causes
problems for some specific use cases of intents. It was revealed
when considering the SOAP intent applying
to the Web services binding, with its qualified forms
SOAP.1_1 and SOAP.1_2.
The flaw concerns the last item in the
list of the definition - item 7 - which reads:
1162 7. and where any unqualified qualifiable
intents are replaced with the default qualified form of that
1163 intent, according
to the default qualifier in the definition of the intent
This step implies that any unqualified
form of a qualifiable intent in the required intent set is taken to mean
the
qualified form using the default qualifier,
come what may.
In the case of the SOAP intents, this
would mean that "SOAP" would be synonymous with "SOAP.1_1"
and
thus it would NEVER be possible to satisfy
@requires="SOAP" with a policy that provided the SOAP.1_2
qualified form of the intent.
This is clearly NOT the basic idea behind
qualifiable intents. In this example, "SOAP" is intended
to mean
"The SOAP protocol must be used,
but it does not matter which version of SOAP is used"
it is *NOT* intended to mean "The
SOAP 1.1 protocol must be used"
The original purpose of the default
qualifier was to guide policy selection so that IN THE ABSENCE OF ANY
OTHER INFORMATION, the unqualified form of a qualifiable intent could be
mapped to a qualified form
using the default qualifier.
However, the presence of other information,
such as a PolicySet which provides "SOAP" and deliberately
maps it to "SOAP.1_2", should
be valid and should work.
Thus the current definition of the required
intent set does not achieve the original goals of intents and should be
modified accordingly.
Proposal:
Remove item 7 from the definition of
the required intent set.
This means that the required intent
set CAN contain the unqualified form of a qualifiable intent.
This unqualified form can be then interpreted
by bindings and policySets in a way that is appropriate to their
configuration, with the use of the default
qualifier being a clause useful in the case where the binding or the
policySet has no other means to choose
which qualifier to apply for the unqualified form of the intent.
I note that both the qualified and the
unqualified forms of an intent are fully discussed later in section 4.12.1
in relation to both bindings and in
relation to policySets.
Yours, Mike.
Strategist - Emerging Technologies, SCA & SDO.
Co Chair OASIS SCA Assembly TC.
IBM Hursley Park, Mail Point 146, Winchester, SO21 2JN, Great Britain.
Phone & FAX: +44-1962-818014 Mobile: +44-7802-467431
Email: mike_edwards@uk.ibm.com
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
3AU
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