Combining Policies (was RE: Partial executability/ determinism of a Chor description language

>>>But if the policy cannot reference the choreography then it becomes a 
useless policy. In case of doubt, I am not saying that the choreography 
should reference the policy, but that the policy should reference the 
choreography.<<<

This type of issue the tip of a HUGE iceberg, specifically how do you
combine things together. Now this is not, IMO, part of the discussion for
this group, but to get flexibility in automated systems that is comparable
to that which humans can provide, there is a lot of work to be done. To
illustrate lets take a few examples of the combinations that you might need
to consider in order to make a decision on what to do ...
1. Choreographies are only allowed if the messages are digitally signed.
2. Business Partners require that messages are digitally signed.
3. A partner requires that the messages sent to some, but not all, of the
services they offer are digitally signed.
4. Repeat the above with some combination of reliable messaging protocol
(you can chose your flavor)
5. Repeat the above with different message formats depending on the location
in which they are being used, for example you need VAT in europe and sales
tax in the US.

... and I haven't even started to consider some of the policy decisions you
mentioned earlier such as whether or not international orders are accepted.

If you think about the number of possible combinations or matches you would
have to make in order to realize interoperability is effectively infinite.
This means that:
1. You can't test them all - there are too many
2. The SME's won't implement them all - they can't afford to.

The only way out of this is to define profiles of sets of accepted standards
and policies that apply - unfortunately no one is working on this ... yet.

David

-----Original Message-----
From: Assaf Arkin [mailto:arkin@intalio.com]
Sent: Friday, May 30, 2003 2:17 PM
To: Burdett, David
Cc: Ricky Ho; Yaron Y. Goland; public-ws-chor@w3.org
Subject: Re: Partial executability/ determinism of a Chor description
language


Burdett, David wrote:

> <DB>I think it more likely that the policies will most often apply to 
> services rather than choreographies. For example the "no international 
> orders" policy could apply to *all* orders. The actual choreography 
> used to place the order is irrelevant.</DB>
>
That's precisely my point. I want to find specific services based on the 
policy. For example, if the policy says "no international order" and 
some service says "I use this policy" and "My country != US", then I 
would not bother using that service.

> <DB>Yes there is. But it is only really relevant to your internal 
> business process (or orchestration) rather than to the choreography 
> because ultimately only the sender of the order and nobody but the 
> sender of the order can decide whether or not to send the order - it's 
> a private process.</DB>
>
Let's say that I find a service. I find a policy. There is no 
association between the policy and the choreography. Finding the policy 
is as useful as knowing that the service definition was created on a 
Sunday afternoon.

But if there is some way for me to determine that the service would 
apply the policy as part of the chorography, then MY implementation can 
do a lot of interesting things, like favoring or avoiding that 
particular service. Of course it's only relevant to my internal 
implementation, and if my internal implementation never evaluates the 
policy it would still be acting based on the choreography. Which is 
something I don't belive we've refuted so far.

But if the policy cannot reference the choreography then it becomes a 
useless policy. In case of doubt, I am not saying that the choreography 
should reference the policy, but that the policy should reference the 
choreography.

arkin

> arkin
>