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Subject: RE: [wsbpel] Abstract BPEL (was RE: [wsbpel] FAQ)

Title: RE: [wsbpel] Abstract BPEL (was RE: [wsbpel] FAQ)


I don't know if I am able/allowed to publish to this list (I just joined :-). IMHO, you will never be able to have a continuum between public and private choreography, let alone abstract and executable orchestration.

Since you mention BPSS, I feel that I might throw some comments about it. Ancient specifications (based on internet times) like BPSS have long established that most B2B interactions require a certain quality of service that only certain protocols can provide. Traditional QOS protocols, part of the ws-stack are helpless with that matter.

For instance BPSS offer at least two levels of protocols: what I call a "business reliable messaging" protocol and a "business transaction protocol" (Bob feel free to jump in to keep me honest on what I say). These protocols are essentials to carry some business activities (not all I grant you, something like the travel agent example does not need that). Assuming that the private chorerography or the deep orchestration layer will implement these protocols is not the best use of your choreography or orchestration resources. These protocols are far better handled by the "Business Service Interface" concept described in the ebXML architecture and the ebXML BPSS specification. I can only speak for myself, but more protocols are needed at the B2B level, I am assuming that the ebBP group will continue enriching these protocols that cannot be handled by your private choreography, before it touches your orchestration layer.

Hope that helps.

tel: 425-649-6584
Cell: 508-333-7634

-----Original Message-----
From: Steve Capell [mailto:steve.capell@redwahoo.com]
Sent: Wednesday, October 22, 2003 11:15 PM
To: 'Satish Thatte'; 'Furniss, Peter'; ygoland@bea.com; 'John Evdemon'; wsbpel@lists.oasis-open.org; 'Dave Welsh'
Subject: RE: [wsbpel] Abstract BPEL (was RE: [wsbpel] FAQ)


Are we confusing a "Business Domain" (eg supply chain) with a business process (eg "purchasing")?  In business process modelling (such as the UN/CEFACT BCF methodology) the collaborative "business process" is typically quite granular (eg an order and order response).  The process is a small part of a business domain such as supply chain. To describe the entire domain with an abstract bpel is a huge challenge but to describe a fairly granual collaboration strikes me as quite do-able and quite useful.

>From my perspective, I would like to be able to completely define a
"public process" using machine readable WS schema in a similar way to ebXML specifications.  For example, to describe a simple order / order response process such as resettaNet PIP3A4 using WS schema I would need:

1       An abstract ws-bpel defining the simple collaboration
2       A ws-policy assertion schema definin the QOS attributes of each
activity (non-repudiation, time to acknowledge, etc)
3       Two XSD schema (one for each message) representing the order and
orderResponse messages defined by the model.
4       Two wsdls (one for each party) with references to the xsd schema
(import), ws-policy (policyRef extension), and ws-bpel role (partnerLinkType extension). 

This complete machine readable "public process" can then be used to configure testing tools (for certification or compliant application, design time tools (for creating "private process" orchestrations, and runtime tools (for managing compliance to public process QOS requirements).

On behalf of the Australian government I am certainly hoping that ws-bpel will provide the capability to describe at least simple collabroative processes - otherwise we will have to fall back on things like ebXML BPSS - but then we'd lose the potential to glue together the "public collabroation" and "private orchestration" in one set of specifications & tools.


Steve Capell
Sydney, Australia
Tel : +61 410 437854
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-----Original Message-----
From: Satish Thatte [mailto:satisht@microsoft.com]
Sent: Thursday, 23 October 2003 11:36 AM
To: Furniss, Peter; ygoland@bea.com; John Evdemon; wsbpel@lists.oasis-open.org
Subject: RE: [wsbpel] Abstract BPEL (was RE: [wsbpel] FAQ)

As I argued during my presentation at the first F2F, the idea that a neutral description of multi-party interaction is essential for business protocol definition is erroneous, and worse, too restrictive.  In particular protocols using full duplex communication are almost impossible to describe without separately describing the external behavior of each party, because the number of states corresponding to races becomes unmanageable and incomprehensible.  Think of a supply chain protocol where an order may be canceled at arbitrary points.  Most neutral protocol descriptions tend to be reduced to finite state machines that are also very poor at describing data dependent aspects, error recovery protocols, etc.  I expect this is what Peter is referring to when he speaks of "heading towards somehting much like on abstract bpel".

I therefore consider Yaron's objection to be groundless and advocate keeping the paragraph as is.

-----Original Message-----
From: Furniss, Peter [mailto:Peter.Furniss@choreology.com]
Sent: Wednesday, October 22, 2003 4:42 PM
To: ygoland@bea.com; John Evdemon; wsbpel@lists.oasis-open.org
Subject: [wsbpel] Abstract BPEL (was RE: [wsbpel] FAQ)

Some of Yaron's comments on the FAQ (most of which I agree with) seem to relate to the power of abstract BPEL

paragraph from the proposed FAQ:

The Business Process Execution Language is a XML-based language for formally describing interoperable business processes and business interaction protocols.  It defines how web services are connected together and in what sequence in order to accomplish a particular task


to which Yaron comments :

BPEL only provides a description of the behavior of a single player in a business process protocol. Since protocols require, by definition, more than one player BPEL is by definition unable to completely describe a business process protocol or to specify how different processes interact beyond describing the behavior of a single participant. Therefore I think this paragraph should be struck.


which was very much my view until I had a conversation with Tony Andrews and got a better understanding of his presentation from the first face-to-face ( http://www.oasis-open.org/archives/wsbpel/200305/msg00172.html). It seemed some things I had thought would be necessary, and which I hadn't seen stated, and so assumed were not in view, were definitely


        - there can be multiple abstract definitions for a single executable, each specifying the dynamic behaviour of one (or set of

related) interfaces, with the other interfaces handled by opaque assignment; the choice of how many of these there are, their level of opacity and the interfaces covered is a design/viewpoint question

        - there can be (and need to be for the "global" picture) abstract bpel definitions for processes that are never going to be in bpel - not least because some are "leaf" processes in the web-service world, and do real work on databases or visible effect on GUIs etc. rather than just defer to yet another web-service, which is all executable bpel can do

        - there can be multiple executable processes matching a single abstract definition - this is just an interface:implementation relationship

(Apologies to Tony if I've mis-represented him). They obviously have some exciting implications for what bpel tools in general might do (especially the middle one - how on earth do you show compatibility between abstract bpel and a legacy app written in cobol with a web-service front end)

But these don't seem to be in the spec. (last one might be). Should it be left to interpretation (and, no doubt, some books) ? 

There's also the possibility of stating the rules (guidelines ? constraints ?) involved in the two abstract bpel definitions that make up either side of a business protocol.

(I should possibly mention that I was for a long time very sceptical about whether bpel or things like it was the way to do this, and thought it could be done with a simpler, less procedural approach. but gradually I found my vague "ideal" was getting necessarily more complex and needing more functionality - in fact heading towards somehting much like on abstract bpel)

Peter (speaking for himself)

> -----Original Message-----
> From: Yaron Goland [mailto:ygoland@bea.com]
> Sent: 22 October 2003 23:09
> To: 'John Evdemon'; wsbpel@lists.oasis-open.org
> Subject: RE: [wsbpel] FAQ
> Some comments
> > -----Original Message-----
> > From: John Evdemon [mailto:jevdemon@microsoft.com]
> > Sent: Tuesday, October 21, 2003 12:44 PM
> > To: wsbpel@lists.oasis-open.org
> > Subject: [wsbpel] FAQ
> >
> >
> >  <<WSBPEL DRAFT FAQ.txt>> Hello all,
> >
> >  A while ago I asked for feedback on a TC FAQ.  I have attached a
> > draft that incorporates some initial feedback from Monica and Ugo.
> > Please respond with any additional questions or concerns.
> >
> > If there is no feedback by 10/28 I will assume the TC is happy with
> > the current version (attached) and submit it to OASIS.
> >
> > Thanks!
> >
> > John
> >
> >

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