NEW ISSUE: Is it possible to use only a piece of a more general policySet?

[David Booz <booz@us.ibm.com>]

TARGET: SCA Policy Framework

DESCRIPTION:

Are policies from a policySet in effect just because the containing policySet is attached to the SCA construct?
1. There could be "standalone" policies in the policySet or there could be defaults from the contained intentMaps.
2. Spec seems to be clear that standalone policies would be in effect, but the spec is not clear that defaults from intentMaps should also be in effect.

It is not clear whether policies in a policySet that are not referenced by the list of required intents are always applicable.
What exactly is the effect of having a list of required intents? Are the intentMaps in the policySet that are not referenced by the list of required intents ignored? Or is the semantic that all parts of the attached policySet always apply, and the list of required intents is used only for overriding the defaults in the contained intentMaps?

How to handle standalone policies should also be addressed while addressing this issue.

In particular, consider the following two cases and the questions they raise:
A> There are no required intents declared, and an attached policySet contains some standalone policies and some intentMaps
Questions:
- Do standalone policies in the policySet apply?
- Should all the intentMaps contained in the policySet be considered? Should the policies for the default qualifier in each considered intentMap be applied?
B> There are required intents declared, and an attached policySet includes intentMaps for some of the required intents, intentMaps for some other intents, and also some standalone policies.
- Do standalone policies in the policySet apply?
- Should intentMaps pertaining to intents that are not listed as required be considered? For each such intentMap, should the policies for the default qualifier be applied?

PROPOSAL:

We explored a few solutions:

1. Restrict Policy Sets to have only a single intent map [AM: We need
multiple intent maps to represent Policy Sets for, for example BP 1.0
that covers multiple policy areas.]
2. Allow the user of a Policy Set to specify which of the multiple *intent maps* should be used.
3. Add an attribute to the Policy Set that says, use the individual intent map that is required or use all the intents maps in the Policy Set.
4. In cases where there are multiple intent maps in a Policy Set each
intent map must have a "Null" option that could be chosen to effectively
remove that intent map from participation. This requires no change to
the spec.


PROVENANCE: SCA-249



Dave Booz
STSM, SCA and WebSphere Architecture
Co-Chair OASIS SCA-Policy TC
"Distributed objects first, then world hunger"
Poughkeepsie, NY (845)-435-6093 or 8-295-6093
e-mail:booz@us.ibm.com
http://washome.austin.ibm.com/xwiki/bin/view/SCA2Team/WebHome