Re: [sca-policy] Intents on conversational scope components

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

Meeraj,

The SCA policy design allows for policy
to be applied either to the whole interface of a service or reference,
or alternatively to be applied to individual
operations within the interface.  It makes no difference whether the
components (or the interfaces) are conversational
or not.

It is up to the designer of the service
to decide which of these approaches to use.

It is certainly simpler to apply policy
to the whole interface.  However, it is also possible for certain
types of
policy that the implications of using
the policy are severe in some sense (eg. heavy processing overhead,
reduced response time, consumption of
resources) in which case the extra effort of identifying only those
particular operations that need the
policy is worthwhile.

So, turning to the actual syntax for
this:

1) Applying policy to the whole interface:

@requires   or    @policySets
 attributes are used, either on the <reference/>, <service/>
or <binding/>

2) Applying policy to individual operations

(this is currently not described in
the Asssembly specification, but in the Policy Framework - there is
an Issue open to fix this)

<service/> <reference/>
and <binding/> elements can all have <operation/> elements
as children,
which are of this type:

    <complexType name="Operation">

            <attribute name="name" type="NCName" use="required"/>

            <attribute name="requires" type="sca:listOfQNames" use="optional"/>

            <attribute name="policySets" type="sca:listOfQNames" use="optional"/>

            <anyAttribute namespace="##any" processContents="lax"/>          

    </complexType>


This allows identification of individual operations by name and the attachment of intents and/or policySets to them.



I note that some folk in the Policy TC are not enthused by this approach (although it is what the current spec says).
There has been some discussion of alternate mechanisms - eg using XPath expressions to pick out the operations.
Whether this will lead to any changes in this area remains to be seen.


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

"Meeraj Kunnumpurath" <mkunnumpurath@googlemail.com>

11/12/2007 19:24

To	sca-policy@lists.oasis-open.org
cc
Subject	[sca-policy] Intents on conversational scope components

Hi,

Are intents on conversational components to be applied for the whole
conversation or individual invocations within the conversation. For
example, with the managedTransaction intent, should the transaction be
demarcated across the conversation or individual invocations within
the conversation.

Thanks
Meeraj

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