OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.

 


Help: OASIS Mailing Lists Help | MarkMail Help

sca-policy message

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]


Subject: Re: [sca-policy] Revised Proposal for Issue 93


I appreciate the time you took to adjust the proposal.  There are other
adjustments that would also need to be made, but I'll refrain because I'm
still stuck on a larger issue.

I can hopefully summarize it as the conflation of intents and policy in a
way that undermines the conceptual differences between intents and policy
sets.  I'm trying to keep an open mind, so in the hopes of furthering the
discussion, I'll re-iterate the points I made (or was trying to make) on
the telecon.

1) Intents are abstract expressions of a requirement that is embodied
within an instance of an SCA component or composition.  In their role as
requirements, they appropriately constrain the environment in which they
execute.

2) PolicySets contain concrete policy expressions.  In some cases, a
policySet can be used to further refine or clarify an intent. We use the
word "provides" to indicate that a policySet is a specific concrete
realization of the abstract requirement embodied in an intent.  We indicate
the same relationship between bindingTypes and intents where we recognize
that executable code can also represent a concrete expression of an
abstract requirement.

The means of attaching intents to SCA composites/components is
insignificant.  We could devise all sorts of way of associating intents
with applications.  As such, it is NOT the external attachment aspect of
your proposal that causes me concern, it is the implications of the use
cases that you use to justify the feature.

My objection comes from the following:
1) What does it mean to change the requirements of an application?  The
dynamicity argument you use essentially boils down to this question.  I'll
confess to not understanding how the intents/constraints of an application
can be changed without changing (or at least re-testing) the application.
On the other hand, changing the policySet which fulfills a particular
realization of an already known requirement should be possible.

2) What does it mean to specify a constraint if some other part of the
development lifecycle can undo the constraint?  We designed the intent FW
precisely to honor this notion of a constraint which is explicitly not a
point of variability in the app.  The concrete realization of the
constraint is the point of variability.

I'll stop there and invite some email discussion.

Dave Booz
STSM, BPM and SCA Architecture
Co-Chair OASIS SCA-Policy TC and SCA-J TC
"Distributed objects first, then world hunger"
Poughkeepsie, NY (845)-435-6093  or  8-295-6093
e-mail:booz@us.ibm.com


|------------>
| From:      |
|------------>
  >--------------------------------------------------------------------------------------------------------------------------------------------------|
  |ashok malhotra <ashok.malhotra@ORACLE.COM>                                                                                                        |
  >--------------------------------------------------------------------------------------------------------------------------------------------------|
|------------>
| To:        |
|------------>
  >--------------------------------------------------------------------------------------------------------------------------------------------------|
  |oasis Policy <sca-policy@lists.oasis-open.org>                                                                                                    |
  >--------------------------------------------------------------------------------------------------------------------------------------------------|
|------------>
| Date:      |
|------------>
  >--------------------------------------------------------------------------------------------------------------------------------------------------|
  |01/20/2010 08:56 AM                                                                                                                               |
  >--------------------------------------------------------------------------------------------------------------------------------------------------|
|------------>
| Subject:   |
|------------>
  >--------------------------------------------------------------------------------------------------------------------------------------------------|
  |[sca-policy] Revised Proposal for Issue 93                                                                                                        |
  >--------------------------------------------------------------------------------------------------------------------------------------------------|





At the end of Monday's call Mike Edwards suggested a change to the model
that would allow intents
to be attached both directly and externally and the set of intents
required to be satisfied would be the union of the
intents attached in these two ways.  This suggestion does simplify the
model and reduces optionality and is.
therefore attractive.  I have revised the proposal for Issue 93 to
reflect this.  The change required merely the
removal of the paragraph spelling out the optionality in section 4.1.
Please take a look.

The proposal for issue 93 that I sent out last week had eternal
attachment for intents paralleling external attachment
for policySets.  If we agree to the simplified model for intents as
discussed above we should also consider
simplifying the attachment mechanisms for policySets.  Let's discuss on
Monday and I can open an issue if need be.
--
All the best, Ashok
[attachment "SCA Policy Framework CD02-Rev6-Issue93A.doc" deleted by David
Booz/Poughkeepsie/IBM] [attachment "SCA Policy Framework
CD02-Rev6-Issue93A.pdf" deleted by David Booz/Poughkeepsie/IBM]
---------------------------------------------------------------------
To unsubscribe from this mail list, you must leave the OASIS TC that
generates this mail.  Follow this link to all your TCs in OASIS at:
https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php




[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]