Re: [sca-policy] Proposal for Issue POLICY-94: Allow intents to beattached using an element

[Mike Edwards <mike_edwards@uk.ibm.com>]

Ashok,

I'm not sure that I see a proposal here
yet.

You say:

"These
functions could be extended and
sharpened to take advantage of attributes on the intentAttachment element."

...but there are no standard attributes
on the intentAttachment element you describe below.

If you mean that there could be extended
attributes on the intentAttachment element, then this is true, but
the Policy spec has no business describing
those extended attributes, nor does it have any business 
in describing any XPath functions which
take advantage of those non-standard attributes.

I think that it would be wise to simply
propose that there is an <intentAttachment/> subelement for both
<binding.xxx/> and <implementation.xxx/>
and that the meaning of these subelements is the same as 
the meaning of the @requires attribute
on those elements.  The description of the <intentAttachment/>
element can indicate its extensibility
via the XSD in the usual way.  (Actually, why isn't the element called
<requires/> ??)

Going any further and discussing new
or changed XPath functions would imply standardizing extension 
attributes is taking things too far,
I believe.


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

From:	ashok malhotra <ashok.malhotra@oracle.com>
To:	OASIS Policy <sca-policy@lists.oasis-open.org>
Date:	01/10/2009 00:40
Subject:	[sca-policy] Proposal for Issue POLICY-94:  Allow intents to be attached using an element

---

At the Boston (Charlestown) f2f we decided to allow
policySets to be 
attached to a SCDL element
using a child element in addition to being attached as the value of an
attribute.

Specifically, policySets can be attached to a SCDL element as the value
of the @policySets attribute or as a
child element, i.e. either as

<service> or <reference>…
<binding.binding-type policySets="listOfQNames">
</binding.binding-type>
…
</service> or </reference>

or as

<service> or <reference>…
<binding.binding-type>
<policySetAttachment name="sns:EnterprisePolicySet"> ...
</binding.binding-type>
…
</service> or </reference>

This issue requests that we make a similar extension for intents. That
is, intents can be attached either as
the value of an attribute

<service> or <reference>…
<binding.binding-type requires="listOfQNames"
</binding.binding-type>
…
</service> or </reference>

or using a child element:

<service> or <reference>…
<binding.binding-type>
<intentAttachment name="sns:mySpecialIntent"> ...
</binding.binding-type>
…
</service> or </reference>

The advantage of allowing intents to be attached using a child element
is that the intentAttachment element can
carry additional information in its attributes. This can be used to turn
the intents on and off -- useful during testing -- and
also to provide information such as the repository from which the 
policySets should be selected to satisfy the intent.

Section 4.4.3 of the Policy Framework spec defines XPath functions that
can be used to attach policySets to SCDL
elements based on features present in the SCDL. Section 4.4.3.2 defines
Intent-based functions that can be used to
attach policySets to SCDL elements based on the presence of specific 
intents. These functions could be extended and
sharpened to take advantage of attributes on the intentAttachment element.

-- 
All the best, Ashok

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