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Subject: RE: [soa-rm-ra] SOA-RA(F) reorganization

Michael, Ken:
There is a major missing point in this discussion.  Michael is always talking about transactional/programmed activities of the organization.  Additionally, SOA works for unprogrammed/authoring/design and development/research activities; witness Google, Yahoo, and other search engines.  I submit that the purpose of these nascent SOA concierge services/repositories is to dynamically link (perform Choreography) functions--though the choreography is performed by a person, rather than through a set of business rules (rules that include knowledge rules, event rules, and value rules).  I discussed this concept in a paper I published in the Journal of Enterprise Architecture in 2006/2007.  Still much of the most value laden work is performed by unprogrammed activities (that's what e-mail, word processing, etc. is all about).
Please don't limit SOA to transactions only.

From: Mike Poulin [mailto:mpoulin@usa.com]
Sent: Monday, April 13, 2009 12:19 PM
To: Ken Laskey
Cc: Rex Brooks; James Odell; soa-rm-ra@lists.oasis-open.org
Subject: Re: [soa-rm-ra] SOA-RA(F) reorganization


if two organisations decide exchange messages, i.e. interact, there is a common/shared reason for this. Such reason IS the orchestration entity, it may be deployed anywhere. Plus, as I mentioned, orchestration may be very dynamic based on required business logic and service descriptions.

Nonetheless, I agree with you that combination of orchestration and choreography is better than they taken separately; it is better if each part minds its own business, i.e. orchestration defines order of functionality invocation and choreography - dynamically assigned message exchange and end-points.

- Michael

----- Original Message -----
From: "Ken Laskey"
To: "Mike Poulin" <MPOULIN@USA.COM>
Cc: "Rex Brooks" , "James Odell" , "soa-rm-ra@lists.oasis-open.org"
Subject: Re: [soa-rm-ra] SOA-RA(F) reorganization
Date: Mon, 13 Apr 2009 11:49:24 -0400


It's been a while since I looked at the WS-CDL draft so I can't comment on specifics.  However, I think the problem is not in choreography, per se, but in the way you see WS-CDL implementing it.

In my mind, I can set up a choreography for an emergency scenario that has a series of agreements on how one should respond to a understandable piece of information, and I can see a very flexible response as the situation unfolds.

Part of the problem with orchestration is it requires *all* participants to work under a single orchestration engine.  This is fine under the notional "enterprise" but what about peer resources that can exchange messages but are otherwise independent?

What happens when a variation of the scenario is not covered by the specifics of pre-programmed orchestration logic?

I am not arguing for one over the other but I see the combination as being more powerful than either alone.  However, this requires SO composition rather than a traditional integration mindset.


On Apr 13, 2009, at 10:38 AM, Mike Poulin wrote:

Unfortunately, Ken, this is the principle point because Choreography constantly screws SO model.
Choreography is classical application integration centric model where each change in the integration requires change in each participant of this integration, code modification, re-compilation and re-deployment. This relates as to the change in the invocation order as to the change in the participants of particular Choreography.
The WS-CDL standard under W3C makes the life even worth – it defines so-called Global Contract, which freezes all participants. If you need to modify any participant due to new business requirements, you have to re-construct the Global Contract and affect all (innocent) participants.
The … standard is so bad that Mr. Ashley McNeile  with his university colleagues tried to construct a mathematical model which externalises choreography scenario from the participants and build it around centralized dispatcher (very similar to Orchestration).
Orchestration is real antipode to Choreography.
As of “Dave Ellis will tell you related to emergency response, where the choreography pattern is vital because you do not know in advance the location and extent of the emergency and thus do not know the resources you will need to orchestrate”, I can say that you do not know where your resources (participants) for choreography will be as well. Emergency is NOT the argument. If you construct a set of choreographies they are solid, monolithic and incapable to be quickly changed in the case of emergency. You have to pre-build all choreographies up-front wasting resources (because you do not know the location, right?)
Orchestration, in the contrast , is absolutely dynamic, if you approach it with a service-oriented mind. As IBM Dynamic Process Edition has proved, Orchestration does not need to know Who and How/Where performs the orchestrated functions. It needs only to know What functions are and Why/Which order of invocation has to be applied. Whatever service meets requirements to the business functionality declared by the Orchestration, it may be used. It also may be reused in absolutely different Orchestration at the same time (due to the match of offered business functionality) because the service does not know where it participates in.
Choreography, as it is defined in the WS-CDL standard under W3C, is an application-oriented, not service-oriented mechanism.
If you need more information on this topic, please, look at ‘Does SOA need a choreography or it can dance by itself?’ (http://it.toolbox.com/blogs/so-enterprise-blog/does-soa-need-a-choreography-or-it-can-dance-by-itself-27775).

- Micahel

----- Original Message -----
From: "Ken Laskey" <KLASKEY@MITRE.ORG>
To: "Mike Poulin" <MPOULIN@USA.COM>
Cc: "Rex Brooks" <REXB@STARBOURNE.COM>, "James Odell" , "soa-rm-ra@lists.oasis-open.org" 
Subject: Re: [soa-rm-ra] SOA-RA(F) reorganization
Date: Sun, 12 Apr 2009 20:44:01 -0400


There are problem, such as Dave Ellis will tell you related to emergency response, where the choreography pattern is vital because you do not know in advance the location and extent of the emergency and thus do not know the resources you will need to orchestrate.

I also don't see the need to change the service with a change in the choreography.  I expect the choreographies are externally maintained patterns.


On Apr 12, 2009, at 7:11 PM, Mike Poulin wrote:

I am in favour of Orchestration for SOA 10 times more than for Choreography because the latter requires services modification for each new choreography it participates in and this decreases SOA flexibility in adopting business changes. Everything Rex said about events and policies is applicable to Orchestration as well but Orchestration is much cleaner from SO perspectives and much more dynamic. In Yahoo! SOA User group, we have discussed this topic a few times and always concluded the advantage of Orchestration over Choreography for service-oriented environment.

- Michael

----- Original Message -----
From: "Rex Brooks" <REXB@STARBOURNE.COM>
To: "James Odell" <EMAIL@JAMESODELL.COM>, soa-rm-ra@lists.oasis-open.org
Subject: Re: [soa-rm-ra] SOA-RA(F) reorganization
Date: Sat, 11 Apr 2009 16:47:14 -0700

If we had spent more time on Choreography, where events trigger 
policy-based rules for transactions and/or communications, it would 
be somewhat easier to pull together a stand alone Policy 
subsection. Of course, Orchestration also employs policy-based 
rules, but resorting to a Conroller Application removes the 
requirement for either human intervention based on judgment 
required by rules and assessing state, or some heuristic algorithm.

I'd still just add the standalone policy subsection rather than 
eliminating the Policies and Contracts which I think we need for 
more reasons than just continuity from the RM.


At 7:03 PM -0400 4/11/09, James Odell wrote:
> Hi Frank,
> Hmmm. While the two "the enforcement of the two is fairly 
> closely aligned" -- contracts are not necessary for Policies, 
> only the other way around. Policies, IMO should stand alone on 
> their own. The CEP folks argue that policies and events are 
> "fairly closely aligned". I can name a half dozen other areas 
> that could say the same. The bottom line is that: Policy is a 
> concept that may be necessary, but not sufficient for other 
> areas. Therefore, I strongly support its own sub-section.
> -Jim
> On 4/11/09 6:11 PM, "Francis McCabe" indited:
> Hi Jim
> Thank you for taking a look.
> As far as policies go, we have havered a little (to use a 
> Scottish-ism) on how to organize it. In the RM work we closely 
> identified the two -- with the distinction being that contracts 
> are agreed to and policies are asserted. Once you have either 
> one, the enforcement of the two is fairly closely aligned.
> Frank
> On Apr 11, 2009, at 2:46 PM, James Odell wrote:
> Hi all,
> After yet another reading of the SOA-RA (Foundation?) and having 
> sat through the recent spate of meetings, I have the following 
> say about the reorganization of the SOA-RA:
> Overall, I think that the chapters and topics are sequenced in a 
> coherent and logical manner. Perhaps, it is because I read it 
> too many times now. But, I don't think so.
> Also, I understand the need to minimize the amount of work 
> needed on the SOA-RA at this point in its development. We need 
> to get it released for public comment - without compromising 
> quality and understandability, of course.
> Having said this, the only thing that bothers me enough to 
> suggest a reorganizational change is the area of Policies:
> 1) Policies, in general, are depicted in document far earlier 
> than they are finally addressed (by 40-50 pages). Since policies 
> - IMO - are an important ingredient in the SOA-RA, I would like 
> to see them addressed earlier. (My personal opinion is that 
> policies are not mentioned anywhere near the amount that they 
> should. For example, they are used in events, composition of 
> services, roles, and organizations. However, since this would 
> involve additions to the current document, I will not push this)
> 2) I strongly dislike grouping the entire topic with contracts. 
> While policies are used for contracts, Policy is a standalone 
> concept - which neither depends on nor is used solely with 
> Contract. (Even the OMG and W3C treat policies as a separate 
> notion.) Why is this reasonable? Because policies are used in a 
> variety of situations - only one of which is contracts. By 
> placing Policies in lock step with (and almost subordinate to) 
> with Contracts is not appropriate, IMO. 3) My suggestion: 
> separate Policies and Contracts into two distinct subsections 
> (e.g., 4.4 and 4.5). In short, this would provide clarity for 
> the notion of Policy and not require much change to the current 
> document.
> All the best,
> Jim

-- Rex Brooks
President, CEO
Starbourne Communications Design
GeoAddress: 1361-A Addison
Berkeley, CA 94702
Tel: 510-898-0670

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7515 Colshire Drive                        fax:        703-983-1379

McLean VA 22102-7508

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