- From: Anthony Nadalin <drsecure@us.ibm.com>
- Date: Sat, 23 Sep 2006 17:17:55 -0500
- To: "Sergey Beryozkin" <sergey.beryozkin@iona.com>
- Cc: Maryann Hondo <mhondo@us.ibm.com>, public-ws-policy@w3.org, public-ws-policy-request@w3.org, "Sergey Beryozkin" <sergey.beryozkin@iona.com>, "William Henry" <william.henry@iona.com>
- Message-ID: <OF29619C24.123F4517-ON862571F2.007A3EDE-862571F2.007A7DB0@us.ibm.com>
>This brings me to a simple conclusion : Policy authors SHOULD be
encouraged to use wsp:optional when using policy asssertions which
advertise capabilities with no associated behavioral requirements and wire
representations in order to widen the service's audience and improve
interoperability. wsp:optional means here that it's a capability which
*may* be used for a service selection. I believe guidelined for policy
authors should be updated.
Don't agree, as policy asssertions which advertise capabilities with no
associated behavioral requirements and wire representations are just policy
asssertions, and require them to use wsp:optional is just plain wrong.
Anthony Nadalin | Work 512.838.0085 | Cell 512.289.4122
"Sergey
Beryozkin"
<sergey.beryozkin To
@iona.com> "Sergey Beryozkin"
Sent by: <sergey.beryozkin@iona.com>,
public-ws-policy- "William Henry"
request@w3.org <william.henry@iona.com>
cc
Maryann Hondo/Austin/IBM@IBMUS,
09/22/2006 05:03 Anthony Nadalin/Austin/IBM@IBMUS,
AM <public-ws-policy@w3.org>,
<public-ws-policy-request@w3.org>
Subject
Re: Policy expressions with no wire
manifestation
Minor omission :
"Making such policy assertion as <oasis:QOSGuarantee> would unnecessarily
limit the audience of this service."
I missed a phrase there, should be
"Making such policy assertion as <oasis:QOSGuarantee> *non-optional* would
unnecessarily limit the audience of this service."
Cheers, Sergey Beryozkin
Iona Technologies
----- Original Message -----
From: Sergey Beryozkin
To: William Henry
Cc: Maryann Hondo ; Anthony Nadalin ; public-ws-policy@w3.org ;
public-ws-policy-request@w3.org
Sent: Friday, September 22, 2006 10:51 AM
Subject: Re: Policy expressions with no wire manifestation
Hi all,
After thinking a bit more about policies which express capabilities with
no wire manifestations and no associated behaviours expected from a
consumer of such policies, I came to some conclusion.
Here's an example :
wsp:Policy>
<wsp:ExactlyOnce>
<wsp:All>
<!--- security assertion -->
<sp:HttpsToken/>
</wsp:All>
<wsp:All>
<!-- capability assertion -->
<oasis:QOSGuarantee>
<NeverEverFails/>
</oasis:QOSGuarantee>
<!--- security assertion -->
<sp:HttpsToken/>
</wsp:All>
<wsp/ExactlyOnce>
<wsp:Policy>
A policy designer wishes to tell to ws-policy aware entities out there
that they must be able to use HTTPS should they attempt to start
communicating with the service.
Futhermore, a policy designer wishes to tell that the service has a
well-known capability to never fail, but is careful to ensure that the
entities not aware of what this means but still meeting a key requirement
of being able to use HTTPS can still enjoy communicating with this
service. A policy author achives this by creating two policy alternatives.
The reason is simple : <oasis:QOSGuarantee> assertion is not a requirement
but a capability which has no wire manifestations and behavioural
requirements for the entities which can understand what it means.
In fact, the above expression, being in a normal form, is equivalent to
this compact expression :
wsp:Policy>
<wsp:ExactlyOnce>
<sp:HttpsToken/>
<oasis:QOSGuarantee wsp:optional="true">
<NeverEverFails/>
</oasis:QOSGuarantee>
<wsp/ExactlyOnce>
<wsp:Policy>
Making such policy assertion as <oasis:QOSGuarantee> would unnecessarily
limit the audience of this service. A requester entity should never fail
if it does not understand what <oasis:QOSGuarantee> given the fact the
only thing it can ever do with it is to note that this service posesses
the advertised quality and see whether it meets its selection criteria or
not.
For example, if a requester searches for services which are known to
publish its message logging traces to a well known external site it shoud
be sufficient for it to be able to recognize a well known
<common:publishTraces href="..."/> rather than fail due to the fact
<oasis:QOSGuarantee/> is not recognized. Likewise those searching for
never failing services should be able to consume those who assert it and
not fail should they not recognize <common:publishTraces href="..."/>.
This brings me to a simple conclusion : Policy authors SHOULD be
encouraged to use wsp:optional when using policy asssertions which
advertise capabilities with no associated behavioral requirements and wire
representations in order to widen the service's audience and improve
interoperability. wsp:optional means here that it's a capability which
*may* be used for a service selection. I believe guidelined for policy
authors should be updated.
At the moment the WS-Policy Framework (primer) uses wsp:optional to mark
assertions which identify behaviours which *may* be engaged. It refers to
such assertions as 'capabilities'. IMHO it's not the best/too broad the
definition and it will cause confusions. For ex :
<mtom:OptimizedMimeSerialization wsp:optional="true"/>. I feel it's better
be additionally categorised as an optional requirement.
Any thoughts or objections ?
Likewise an assertion like <sp:MustSupportRefKeyIdentifier /> does not
fall into this category because a policy author *requires* a consuming
entity to understand it, ortherwise the secure processing on either side
will fail.
Thanks, Sergey Beryozkin
Iona Technologies
It is my understanding that people are using the wsp:optional to handle
this. So if the requester (consumer) doesn't know about it they can ignore
it.
This works BUT it is really using wsp:optional in an unintended way. The
truth is that such an assertion is not really optional it's only optional
in the sense that the requester can ignore it however the provider must be
providing this level of service and the requester must do nothing - so in
that sense it really isn't optional it's just a handy use of the
wsp:optional.
This is one of the reasons I think there could be another attribute
missing (like the wsp:local).
Another reason for having such an attribute would be for the generic
engine to be able to handle such a thing consistently in all
implementations. e.g. if I had a wh:local then I'd be forcing the
requester to either know about my namespace or assume that they can't use
this service. I think it can just make things messier than they need to
be.
Having said all that I understand the effort that introducing a new
attribute would mean and seeing as you can get a similar affect using
things like wsp:optional (albeit in an unintended way) I expect push back
on the idea.
Regards,
William
On Sep 20, 2006, at 11:46 AM, Beryozkin, Sergey wrote:
Hi Maryann, others
this is most helpful...
"I would note that if you're "using the assertion for selection", it
could
imply that you know what it is."
Ok, I think I start understanding it (fingers crossed :-)). A
requester runtime may be required to select services which are
highly available. It expects providers to advertize well-known
<oasis:HighlyAvailable/> assertions. If a provider advertizes a
policy which have no <oasis:HighlyAvailable/> assertions then the
intersection will fail. I think it's reasonable.
Now consider a different case.
A requester runtime has no priori policy requirements. However it
understands all well-known security assertions but no others ones.
It has found a service which requires that a requester supports some
security policies.
Futhermore, a provider wishes to advertize some of its capabilities,
namely that it's the best service around. A requester does not know
yet about such assertions and is not even planning to use assertions
like this for services selection.
How would we do it ?
Like this ? :
<wsp:Policy>
<wsp:ExactlyOnce>
<wsp:All>
<!--- security assertion -->
<sp:HttpsToken/>
</wsp:All>
<wsp:All>
<!-- capability assertion -->
<oasis:QOSGuarantee>
<TheBestServiceInThisCategory verifiedBy="..."/>
</oasis:QOSGuarantee>
<!--- security assertion -->
<sp:HttpsToken/>
</wsp:All>
<wsp/ExactlyOnce>
<wsp:Policy>
Thanks,
Sergey Beryozkin
Iona Technologies
----- Original Message -----
From: Maryann Hondo
To: Sergey Beryozkin
Cc: Anthony Nadalin ; public-ws-policy@w3.org ;
public-ws-policy-request@w3.org ; Sergey Beryozkin
Sent: Wednesday, September 20, 2006 2:17 PM
Subject: Re: Policy expressions with no wire manifestation
Sergey,
I responded to your other mail ...so this is a bit of a repetition.
In the guidelines document, Umit and I have attempted to capture
"observations" about the use of optional, and this might
be a case where it would be useful. I would note that if you're
"using the assertion for selection", it could
imply that you know what it is. Whether or not it is required on
the wire is a facet of the behavior associated with the assertion.
Each set of authors is given a set of tools by the specifications,
but the authors need to craft the assertions.
Maryann
"Sergey Beryozkin" <
sergey.beryozkin@iona.com>
Sent by:
public-ws-policy-request@w3. To
org "Sergey Beryozkin" <
sergey.beryozkin@iona.com>, Anthony
Nadalin/Austin/IBM@IBMUS
09/20/2006 05:35 AM cc
<public-ws-policy@w3.org>, <
public-ws-policy-request@w3.org>
Subject
Re: Policy expressions with no wire
manifestation
Hi there
That was a response in a hurry so I take it back. Before flooding
the group concalls with trivial issues I'd rather attempt to make
my question as clear as possible. Note that I may indeed be
confused, but if so then I'd appreciate an answer which would help.
Consider this example :
<wsp:Policy>
<wsp:ExactlyOnce>
<oasis:QOSGuarantee>
<NeverFails/>
<TheBestServiceInThisCategory verifiedBy="..."/>
<oasis:QOSGuarantee>
<wsp/ExactlyOnce>
<wsp:Policy>
This is an example of a policy with a single alternative. This
alternative contains non-optional assertions
defined by a policy profile spec published a month ago. These
assertions have no wire manifestations.
A ws-policy aware (requester) entity whose runtime has not been
updated yet to recognize <oasis:QOSGuarantee> is about to start
communicating with the service which advertizes this policy.
Given the fact that it's likely ws-policy aware requesters will
refuse to start talking to a service should they fail to support
the above policy and that the fact whether this requester supports
this policy or not will have no effect on the actual communication
with the service this policy attached to, my understanding is that
such assertions with no wire manifestations SHOULD be marked as
wsp:optional :
<wsp:Policy>
<wsp:ExactlyOnce>
<oasis:QOSGuarantee wsp:optional="true">
<!-- -->
<oasis:QOSGuarantee>
<wsp/ExactlyOnce>
<wsp:Policy>
This means a requester may use this policy for a service selection
but doesn't need to refuse talking to this service should it fail
to recognize the policy.
Does it make sense ?
What is the group's position on this issue ?
Thanks
Sergey Beryozkin
Iona Technologies
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Received on Saturday, 23 September 2006 22:20:42 UTC