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Subject: RE: [wsbpel] Issue 72 and WS-I BP 1.0


Title: Message
Dear Ugo,
 
Not really.  The point I was making is that one way to achieve a high probability of interoperation between two or more independently implemented systems is for the implementers to follow specifications that have no options.  So to achieve its goal the WS-I BP has to be very restrictive.  If it has get out clauses - and implementers make use of them then it does not achieve its goal.  There are alternative approaches to achieving interoperability that I suggested and these include a basic 'no-options' communications stack and the ability to negotiate the use of other functions / features dynamically at run time, and a flexible approach coupled with the use of 'agreements' between groups that wish to interoperate for a particular purpose (which is essentially the CPP/A approach).
 
So complying with the BP whilst using something else that SOAP over HTTP is a side issue.  But while we are on it perhaps you could explain it in more detail as I still do not see it.  Please refer to the trail of Requirements that I gave - see below.  But in particular I read: 

5.5.1 Use of SOAP Binding

The Profile limits the choice of bindings to the well defined and most commonly used SOAP binding. MIME and HTTP GET/POST bindings are not permitted by the Profile.

R2401 A wsdl:binding element in a DESCRIPTION MUST use WSDL SOAP Binding as defined in WSDL 1.1 Section 3.

Note that this places a requirement on the construction of conformant wsdl:binding elements. It does not place a requirement on descriptions as a whole; in particular, it does not preclude WSDL documents from containing non-conformant wsdl:binding elements

This seems to make the requirement fairly clear.  It says elsewhere that only only Rnnnn statements count when it comes to considering conformance.  The note is purely informative but that says you can include other kinds of binding in a WSDL document but they are non-conformant.
 

Best Regards,

Tony                          

Tony Fletcher

Technical Advisor
Choreology Ltd.
68, Lombard Street, London EC3V 9L J   UK

Phone: 

+44 (0) 870 7390076

Mobile:

+44 (0) 7801 948219

Fax:   

+44 (0) 870 7390077

Web:

www.choreology.com

Cohesions™

Business transaction management software for application coordination

Work: tony.fletcher@choreology.com

Home: amfletcher@iee.org

-----Original Message-----
From: Ugo Corda [mailto:UCorda@SeeBeyond.com]
Sent: 03 October 2003 16:11
To: Fletcher, Tony
Cc: BPEL OASIS
Subject: RE: [wsbpel] Issue 47 and WS-I BP 1.0

Hi Tony,
 
It looks like one of your major concerns about using BP 1.0 is its alleged prohibition of using any WSDL bindings other than SOAP/HTTP. Please look at my previous notes for my elaboration on this subject.
 
Ugo
-----Original Message-----
From: Fletcher, Tony [mailto:Tony.Fletcher@choreology.com]
Sent: Friday, October 03, 2003 7:11 AM
To: Ugo Corda
Cc: BPEL OASIS
Subject: RE: [wsbpel] Issue 47 and WS-I BP 1.0

Dear Ugo and others,
 
First I have to say that the opinions expressed in this mail are my own individual opinions based on my current understanding (that is always amenable to update on the absorption of new information!).
 
Saying that a minimum of one portType must obey the WS-I Basic Profile is an interesting get out, but it raises other issues as Peter has shown and fudges the real issue - see below.
 
It seems that the application of the BP will not material affect the BPEL language itself except possibly in some details (but this could be significant - the devil is sometimes in the detail!).
 
However the BP, if applied strictly - which is its whole purpose - will effect BPEL driven communications.
 
My impression is that the prime motivation for BPEL is portability.  If the TC is going to adopt interoperability as a first rank goal, then I think we should recognise this and maybe even have a vote on whether this should be a prime goal.
 
BPEL demands the use of WSDL and if we then apply the BP then this not only constrains the WSDL but also demands the constrained use of SOAP,  HTTP, and XML.  For instance SOAP over SMTP is clearly non-conformant
(BP 1.0a R0001 --> R2401 (R2702)  --> R1141(R1140) R4004 R2800 & R2801
 
 
Let us take a step back for a moment.
 
It seems to me that if we do accept BPEL instance run time interoperability as a major goal (and as I have stated above I think that is an issue the TC should explicitly decide on) then there are two extreme ways to achieve this - and probably a spectrum of options in between.
 
At one extreme you specify just one way of doing something and everyone has to implement all that is specified in the complete stack.  Nothing is optional to implement and the meaning of everything is made as clear as possible (this is always good independent of the approach!).  Not everything has to be used on each instance of communication but this is the only kind of optionality permitted.  It must always be possible to initiate a communication and get an understandable response (which is why only one way is supported in this case SOAP over a particular HTTP style and SOAP over SMTP is not supported).  This is the approach taken by the WS-I BP.
Pro:  The approach has worked well in the past.  Con:  It limits flexibility in the cause of interoperability.
 
The other extreme is specify whatever might be reasonably implemented and used, and to let partners agree which particular set of options they will use for communication between them.  This is essentially the approach used for EDI (through Message Implementation Guidelines) and this approach has been brought up to date in ebXML with the concept and use of a CPA.  The CPA is an agreed format configuration file that a group of partners agree to apply to their systems when engaging in the specified business process(es).  It can be agreed manually or semi-automatically.  It fixes the options to be used for those instances of communications and different CPAs can be applied dynamically if required.
Pro:  Allows flexibility in specification and implementation.  Con:  Automation of this approach is relatively new and it would require the development of a CPP/A for web services (the existing ebXML one could be used as a basis if it was modularised so that unwanted modules could be omitted and new web service relevant ones introduced)
 
In between these two extreme there is an approach that specifies a basic communications stack that must always be implemented, which allows the dynamic negotiation of additional features on any instance of communication.
 
Variations on these major possibilities are clearly possible such as having 2 or 3 (or more, but a small number) of 'Basic Profiles' and a very simple pre- communication agreement mechanism (slim line CPA) to agree which to use.
 
I think this is the territory we have, perhaps somewhat unwittingly, strayed into with the raising of the application of the WS-I BP, or not.
 

Best Regards,

Tony                          

Tony Fletcher

Technical Advisor
Choreology Ltd.
68, Lombard Street, London EC3V 9L J   UK

Phone: 

+44 (0) 870 7390076

Mobile:

+44 (0) 7801 948219

Fax:   

+44 (0) 870 7390077

Web:

www.choreology.com

Cohesions™

Business transaction management software for application coordination

Work: tony.fletcher@choreology.com

Home: amfletcher@iee.org



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