Re: Ordering of Assertions: Comment on WS-Policy Primer LCWD

Hi

One concern about introducing some ordering constraint  into a WS-Policy language is that it would limit IMHO the utility of this language, preventing it from being used as a general policy language used in domains other than web services.

For example, lets take an imaginary wsp:AllInOrder. As far as I understand, the motivation behind introducing
an operator AllInOrder is for the policy engine to tell the runtime in what order policies need to be applied.

I see few problems here :
* policy engine (and framework) would take extra/foreign responsibility, though it's up to the runtime to decide how to process given policy expressions.
* expotential complexity growth, once we start considering things like intersection for example, does this intersect :
<All><A></All> and <AllInOrder><A></AllInOrder>
* this limits the general utility of the language, because something like AllInOrder would be introduced to address a concern specific to web services only. 
* finally, I don't understand how a generic AllInOrder approach makes like for consumers easier if compared to using a domain specific policy expression specifying some ordering. Yes, policy engine will recognize that AllInOrder children are in order but it's up to the runtime  to figure out what this ordering means, which is a domain-specific knowledge.
Seems like <acme:ordering order = "1 3 2" /> (not as a generic approach) or <acme:OneThreeTwo/> is what is needed.

Thanks, Sergey



----- Original Message ----- 
From: "David Orchard" <dorchard@bea.com>
To: <ashok.malhotra@oracle.com>
Cc: <public-ws-policy@w3.org>
Sent: Thursday, October 11, 2007 3:13 PM
Subject: RE: Ordering of Assertions: Comment on WS-Policy Primer LCWD



I think the onus is on you to prove something, rather than me to prove
nothing, especially if you want the WG to do something.

I know you are arguing that some policies need ordering.  I'm arguing
you need to show some policies that need ordering.

Cheers,
Dave 

> -----Original Message-----
> From: ashok malhotra [mailto:ashok.malhotra@oracle.com] 
> Sent: Thursday, October 11, 2007 3:28 AM
> To: David Orchard
> Cc: public-ws-policy@w3.org
> Subject: Re: Ordering of Assertions: Comment on WS-Policy Primer LCWD
> 
> I'll make it still shorter:
> 
> I'm arguing that SOME policies need ordering.  The Policy 
> Framework says so and the fact the there are ordering 
> assertions in WS SecurityPolicy confirms this.
> 
> Are you arguing that NO policies need ordering?
> 
> Ashok
> 
> David Orchard wrote:
> 
> >I'll make my note even shorter.  
> >
> >What situations are those?
> >
> >For the 2nd time, you have failed to specify a single situation that 
> >requires a change to WS-Policy.  You've described a problem that 
> >already has a solution and quotes from other people but 
> those are not 
> >answers to my question.
> >
> >In the absence of any real-world problem, the obvious thing for 
> >WS-Policy WG to do is to close with no action.
> >
> >Cheers,
> >Dave
> >
> >  
> >
> >>-----Original Message-----
> >>From: ashok malhotra [mailto:ashok.malhotra@oracle.com]
> >>Sent: Wednesday, October 10, 2007 1:59 PM
> >>To: David Orchard
> >>Cc: public-ws-policy@w3.org
> >>Subject: Re: Ordering of Assertions: Comment on WS-Policy 
> Primer LCWD
> >>
> >>Hi Dave:
> >>I used the fact that WS-SecurityPolicy discusses order to 
> motivate the 
> >>need for order in at least some policies.
> >>I also quoted from the note from Tony Rogers.  
> Subsequently, there was 
> >>a note from Bob Natale who agrees that order is important 
> but does not 
> >>like the solution I suggested.
> >>
> >>What needs to be made clear is that order is not important in all 
> >>policies, but there are situations where it is important 
> and for these 
> >>situations we need a solution.
> >>
> >>Ashok
> >>
> >>David Orchard wrote:
> >>
> >>    
> >>
> >>>>-----Original Message-----
> >>>>From: public-ws-policy-request@w3.org 
> >>>>[mailto:public-ws-policy-request@w3.org] On Behalf Of 
> ashok malhotra
> >>>>Sent: Wednesday, October 10, 2007 9:56 AM
> >>>>To: public-ws-policy@w3.org
> >>>>Subject: Ordering of Assertions: Comment on WS-Policy Primer LCWD
> >>>>   
> >>>>
> >>>>        
> >>>>
> >>><snip/>
> >>> 
> >>>
> >>>      
> >>>
> >>>>In many cases the
> >>>>order in which assertions are processed may not matter, but
> >>>>        
> >>>>
> >>where it
> >>    
> >>
> >>>>does matter do we need to specify a special assertion for
> >>>>        
> >>>>
> >>every pair
> >>    
> >>
> >>>>of assertions that need to be ordered? Clearly, this is not
> >>>>        
> >>>>
> >>feasible
> >>    
> >>
> >>>>as the Policy processing engine will need to be undated
> >>>>        
> >>>>
> >>whenever a new
> >>    
> >>
> >>>>ordering assertion is added. So, what we need is a 
> general-purpose 
> >>>>ordering assertion.
> >>>>   
> >>>>
> >>>>        
> >>>>
> >>>Your note jumps from assumption to conclusion to design with great 
> >>>speed, indeed from assumption to conclusion within 3
> >>>      
> >>>
> >>sentences.  Those
> >>    
> >>
> >>>3 fleety sentences do not answer my previous emails central
> >>>      
> >>>
> >>question of
> >>    
> >>
> >>>"when does order matter?".  In case my question was 
> missed, perhaps 
> >>>because of burdensom length of my previous message, I'll ask
> >>>      
> >>>
> >>again more
> >>    
> >>
> >>>succinctly:
> >>>
> >>>When does order matter?  
> >>>
> >>>Until the use case is agreed by the WG, design discussions 
> are very 
> >>>premature IMHO.
> >>>
> >>>Cheers,
> >>>Dave
> >>>
> >>>
> >>> 
> >>>
> >>>      
> >>>
> >>--
> >>All the best, Ashok
> >>
> >>    
> >>
> >
> >  
> >
> 
> 
> --
> All the best, Ashok
>

----------------------------
IONA Technologies PLC (registered in Ireland)
Registered Number: 171387
Registered Address: The IONA Building, Shelbourne Road, Dublin 4, Ireland