RE: [sca-policy] ISSUE 7: Required intents on interfaces [Implicit additionof intents based on a service or reference's @requires list]

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

Folks,

Some suggested wordsmithing.

Required Intents on Interfaces

 
Intents can optionally be applied
to interfaces. For WSDL Port Type elements (WSDL 1.1) and for WSDL Interface
elements (WSDL 2.0), the @requires attribute can be applied that holds
a list of intent names that are required for the interface.  Other
interface languages may define their own mechanism for specifying a list
of required intents.  Any service or reference that uses an interface
with required intents implicitly adds those intents to its own @requires
list.
 
Because intents specified on
interfaces can be seen by both the provider and the client of a service,
it is appropriate to use them to specify characteristics of the service
that both the developers of provider and the client need to know.  For
example, the fact that an interface is conversational is such a
characteristic, since both the client and the service provider need to
know about the conversational semantics.


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

"Michael Rowley" <mrowley@bea.com>

29/10/2007 17:59

To	"Patil, Sanjay" <sanjay.patil@sap.com>, <sca-policy@lists.oasis-open.org>
cc
Subject	RE: [sca-policy] ISSUE 7: Required intents on interfaces [Implicit addition of intents based on a service or reference's @requires list]

I took an action item to specify
more specific text to add to the Policy spec for resolution of issue 7.
 
It was a real pain to avoid
the word “should” when I was trying to describe how the construct should
be used.  I eventually succeeded, but as I mentioned on the call,
I’m not sure that it will be worth while to do this throughout the spec.
 Take a look at the Java EE spec (71 uses) or the JPA spec (67 uses)
and try to imagine getting rid of all those shoulds and using other language
instead.  Looking at WS-BPEL 2.0, you can see that it uses both “SHOULD”
and “should”, and has 24 uses of the latter.  The capitalized form
is used when describing what compliant systems SHOULD do, while the latter
is used to describe what people should do.
 
Now to the suggested new text...
 
I would propose that a new
section be added somewhere that the editors think is appropriate (probably
somewhere inside the section titled “Attaching Intents and PolicySets
to SCA Constructs”).
 
Required Intents on Interfaces

 
The @requires attribute can
be applied to WSDL Port Type elements (WSDL 1.1) and to WSDL Interface
elements (WSDL 2.0) that holds a list of intent names that are required
for the interface.  Other interface languages may also define their
own mechanism for specifying the list of required intents.  Any service
or reference that uses an interface with required intents implicitly adds
those intents to its own @requires list.
 
Because intents specified on
interfaces can be seen by both the provider and the client of a service,
it is appropriate to use them to specify characteristics of the service
that both the developers of provider and the client need to know.  For
example, the fact that an interface is conversational is such a
characteristic, since both the client and the service provider need to
know about the conversational semantics.
 
Michael

---

From: Michael Rowley [mailto:mrowley@bea.com]
Sent: Thursday, October 25, 2007 10:54 AM
To: Patil, Sanjay; sca-policy@lists.oasis-open.org
Subject: RE: [sca-policy] ISSUE 7: Required intents on interfaces [Implicit
addition of intents based on a service or reference's @requires list]
 
 
We don’t currently have an
operational distinction between implementation intents and interaction
intents.  We define the terms, but none of our mechanisms are tied
to those terms.
 
With the current definition
of intents on interfaces, references that use an interface implicitly require
all intents specified on that interface.  This certainly fits interface
intents such as “conversational” and “joinsTransaction” well.  If
we changed the semantics, I’m not sure what we would change them to.
 
Michael

---

From: Patil, Sanjay [mailto:sanjay.patil@sap.com]
Sent: Thursday, October 25, 2007 10:37 AM
To: Michael Rowley; sca-policy@lists.oasis-open.org
Subject: RE: [sca-policy] ISSUE 7: Required intents on interfaces [Implicit
addition of intents based on a service or reference's @requires list]
 
 
Are we ruling out the possibility
of annotating interfaces with intents for any implementation policies?
For example, an interface with operations whose invocations should be audited
may be annotated with @requires("auditing").  In this example,
the client does no have to be aware of the intents on the interface, I
believe.
 
-- Sanjay

---

From: Michael Rowley [mailto:mrowley@bea.com]
Sent: Tuesday, Oct 23, 2007 8:04 AM
To: Patil, Sanjay; sca-policy@lists.oasis-open.org
Subject: RE: [sca-policy] ISSUE 7: Required intents on interfaces [Implicit
addition of intents based on a service or reference's @requires list]
 
I don’t think it is possible
to have an intent on an interface and _not_ have the client see
it, since the client sees the interface.  E.g.:
 
@requires(“confidentiality”)
interface Foo {
   ...
}
 
 
Michael

---

From: Patil, Sanjay [mailto:sanjay.patil@sap.com]
Sent: Monday, October 22, 2007 6:51 PM
To: Michael Rowley; sca-policy@lists.oasis-open.org
Subject: RE: [sca-policy] ISSUE 7: Required intents on interfaces [Implicit
addition of intents based on a service or reference's @requires list]
 
 
Do we need to limit the use of
intents on interfaces to cases where the intents are part of the contract
between the provider and the contract? Why shouldn't we leave the door
open for allowing interfaces to declare requirements for implementation
policies (that are not necessarily visible to the clients)?
 
I think it may be enough description
to say that - "Intents may also be specified on an interface and when
present, they apply to the Services and Reference using that interface".
 
Rest of the proposal looks good
to me.
 
-- Sanjay

---

From: Michael Rowley [mailto:mrowley@bea.com]
Sent: Monday, Oct 22, 2007 14:56 PM
To: sca-policy@lists.oasis-open.org
Subject: RE: [sca-policy] ISSUE 7: Required intents on interfaces [Implicit
addition of intents based on a service or reference's @requires list]
The policy spec should also
describe why an intent should be placed on an interface.  I would
propose something like the following:
 
“Intents should be specified
on interfaces when they should be seen by both the provider and the client
of the service and should be treated as part of the contract between provider
and the client.”
 
I believe that the policy set
selection algorithm also needs to be modified to reflect these semantics.
 We could do this by adding a step between step A2 and A3 which says:

A 2.5.  If the target
element is a binding, include all required intents defined on the interface
that provides the type for the service or reference that the binding is
on (i.e. follow this path: binding->service->interface->@required).
 
Michael

---

From: Joshi, Kaanu [mailto:Kaanu.Joshi@patni.com]
Sent: Wednesday, October 17, 2007 2:04 AM
To: sca-policy@lists.oasis-open.org
Subject: [sca-policy] ISSUE POLICY-7: Required intents on interfaces
[Implicit addition of intents based on a service or reference's @requires
list]
 
Hi,
 
Please find the link to the
JIRA system: http://www.osoa.org/jira/browse/POLICY-7
 
The subject has been modified
to: Implicit addition of intents based on a service or reference's @requires
list
 
Regards,
Kaanu Joshi
 
PS: In conformance with newly
adopted issues process.

---

From: Michael Rowley [mailto:mrowley@bea.com]
Sent: Monday, October 08, 2007 9:12 PM
To: sca-policy@lists.oasis-open.org
Subject: [sca-policy] NEW ISSUE: Required intents on interfaces
 
 
TARGET: SCA Policy Framework Specification
 
DESCRIPTION:
The input specification to the SCA Assembly
TC has the following paragraph starting at line 900:
 
The @requires attribute can be applied
to WSDL Port Type elements (WSDL 1.1) and to WSDL Interface elements (WSDL
2.0).  The attribute contains one or more intent names, as defined
by the
Policy Framework specification [10].
Any service or reference that uses an interface with required intents implicitly
adds those intents to its own @requires list.
 
However, the policy framework specification
has no description of what it means for a policy intent to be required
by an interface.  I believe this definition belongs in the policy
framework specification.
 
PROPOSAL
 
Add this paragraph (or something similar)
to the policy framework specification.
 

http://www.patni.com
World-Wide Partnerships. World-Class Solutions. 
_____________________________________________________________________ 

This e-mail message may contain proprietary, confidential or legally privileged
information for the sole use of the person or entity to whom this message
was originally addressed. Any review, e-transmission dissemination or other
use of or taking of any action in reliance upon this information by persons
or entities other than the intended recipient is prohibited. If you have
received this e-mail in error kindly delete this e-mail from your records.
If it appears that this mail has been forwarded to you without proper authority,
please notify us immediately at netadmin@patni.com and delete this mail.
_____________________________________________________________________

---

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