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Subject: Re: [wsbpel] Issue 82 - Proposal to resolve 82 and other abstract process issues


I believe the distinctions are orthogonal to one another, and that we  
are looking at "wide" vs. "deep" vis-a-vis what can be accomplished  
completely per the level (high and abstract vs. low and detailed). By  
going "wide" and approaching the issue at a high enough level, as per  
Peter's proposal, we can provide a complete-enough abstract definition.  
Some tweaking of the definition for everyone's comfort level may be  
needed, but I feel that profiles takes us away from "wide" and abstract  
and introduces much complexity, which I feel to be more than necessary.  
I also feel that going too "deep" in the interpretation framework, and  
not sticking to the abstract level of Peter's proposal, will  
reintroduce the sort of issues that the SC wrestled with earlier this  
year. I agree with your point #1 (from  
http://lists.oasis-open.org/archives/wsbpel/200412/msg00023.html), but  
I feel that otherwise Peter's definition is generally complete to  
address absBPEL at the "wide", abstract level. I'm for avoiding  
profiles altogether, and sticking to an abstract level for the  
definition - if not Peter's proposal, then Peter's proposal as a base  
with some tweaking,


On 12/12/2004, at 21:50, Satish Thatte wrote:

> Charlton,
> I believe the distinction is not so much between wide and narrow as  
> between a completely vs incompletely defined notion of abstract  
> process, either singular, as you seem to prefer, or plural.  The  
> notion in BPEL4WS 1.1 is singular and Peter's proposal does not  
> actually capture it.  I showed what needs to be added to Peter's  
> proposal to make it correspond to AP1.1.  The only reason to introduce  
> profiles is to allow new interpretations such as templates that are  
> not present in the spec today.  The TC should decide if we want  
> singular or plural interpretation of abstract processes.  But we do  
> need an interpretation framework that is actually specified to the  
> point where the semantic interpretation is unambiguous.  For that  
> Peter's proposal needs some additions, as I explained in my mail  
> http://lists.oasis-open.org/archives/wsbpel/200412/msg00023.html.
> Peter's proposal is indeed very close to what we need.  I hope we will  
> have an amended proposal that fills the remaining gaps to discuss  
> during the face-to-face meeting.
> Satish
> -----Original Message-----
> From: Charlton Barreto [mailto:charlton_b@mac.com]
> Sent: Friday, December 10, 2004 5:11 PM
> To: <wsbpel@lists.oasis-open.org> <wsbpel@lists.oasis-open.org>
> Cc: Peter Furniss; Danny van der Rijn
> Subject: Re: [wsbpel] Issue 82 - Proposal to resolve 82 and other  
> abstract process issues
> I agree with Peter's proposal as is and believe this is the better
> route to resolving the outstanding absBPEL issues. I feel that it is
> preferred to take a "wide", more abstract approach as opposed to a
> "deep", more detailed one, especially given the difficult on agreeing
> upon the details.
> Likewise, I feel that adding profiles/dialects to absBPEL would only
> add complexity, impact interoperability, and take absBPEL "deeper" than
> needed or is resolvable, and agree with Martin's point on the issue.
> I'd prefer to stick to Peter's "wide" approach as it addresses the
> issues well enough at a high level.
> On 02/12/2004, at 02:40, Furniss, Peter wrote:
>> It was my original thought that nothing is a valid replacement to
>> opaque, though looking at the text, it doesn't read that way.
>> Suggest adding, at the end of [4]:
>> This includes the case where, if otherwise valid, an opaque entity
>> is removed without replacement in a corresponding
>> executable artifact)
>> ([4] and [5] deliberately avoid the implication that the
>> concretization is necessarily executable bpel, so "syntactically" may
>> be over-specific)
>> Peter
>> -----Original Message-----
>> From: Danny van der Rijn [mailto:dannyv@tibco.com]
>>  Sent: 01 December 2004 17:59
>> To: wsbpel@lists.oasis-open.org
>> Subject: Re: [wsbpel] Issue 82 - Proposal to resolve 82 and other
>> abstract process issues
>> i would explicitly add to your proposal that it is allowed that
>> "opaque" be removed completely in an executable realization, so long
>> as such removal is syntactically valid. in other words, my current
>> reading is that while <opaque> -> <empty> is valid, <opaque> ->   
>> <!-- removed opaque --> is not.  my opinion is that it should be. 
>> same for attributes.
>> danny
>> Furniss, Peter wrote:
>>  Taking into account previous discussions and definitions,  including
>> the Abstract BPEL
>> sub-group work, the  following definition of Abstract BPEL is proposed
>> as the  resolution
>> of issue 82, to be included in WS-BPEL v2.0.  This definition would
>> supercede the v1.1
>> definition.
>>  A resolution in principle of issue 107 is also proposed, in line with
>> this defintion.
>> The other abstract issues can then be rapidly resolved in line with
>> these proposals:
>>  91, 97, 99 - abstract processes ARE allowed to omit/hide the features
>> mentioned. The
>> schema should make the  elements in question optional and, in line
>> with 107, allow
>>  explicit <opaque> as an alternative.
>>  109 - close with no change, mark as revisitable
>>  (The existing proposals for some of these issues are already in line
>> with this
>> proposal.)
>>  A corollary of [2] below is that the content of the  "extensions for
>> executable
>> processes" would become part of  the main body.
>> Proposal for Issue 82:
>> Abstract BPEL definition:
>>  A BPEL abstract process is a partially specified process that  is not
>> intended to be
>> executed. Executable and abstract BPEL  processes share the same
>> expressive power, while
>> the latter  allows process definitions that are capable of
>> abstracting  away operational
>> details. Whereas executable processes are  fully concretized and thus
>> can be executed, an
>> abstract  process lacks some of the required concrete operational 
>> details expressed by or
>> when mapping it to a fully executable  artifact. An abstract BPEL
>> process must be
>> explicitly  declared as 'abstract'.
>>  Abstract processes serve a descriptive role. A BPEL abstract  process
>> can define the
>> publicly visible behavior of some or all of the services  it offers
>> ("myRole" in its
>> partnerLinks), which may include  its interactions along its
>> partnerLinks with other
>> services.  Alternatively, A BPEL abstract process can define a
>> process  "template"
>> embodying domain-specific best practices, encoded  in a
>> platform-neutral and portable way
>> by both enterprises  and vertical standards organizations. The process
>> "template"
>>  captures some essential process logic while leaving out  operational
>> details that will be
>> concretized by the  enterprises and vertical standards organizations
>> when mapping  the
>> partial process specification to a fully executable artifact.
>>  Semantics of Abstract Processes:
>>  [1]  Although it might contain complete information that
>>  would render it executable as specified for executable BPEL,  its
>> abstract status states
>> that any concrete realizations of  it may perform additional
>> processing steps that are not
>>  relevant to the audience to which it has been given. The  minimum
>> criteria for an abstract
>> process is defined in this  specification while completeness is left
>> undefined.
>>  [2]  Abstract processes permit the use of all of the  constructs of
>> executable processes.
>> Thus there is no  fundamental expressive power distinction between
>> abstract and
>>  executable processes.
>>  [3]  An abstract process may omit operational details that are
>> mandatory for BPEL executable
>> processes either through the omission of specific BPEL elements or
>> attributes listed
>>  in the specification, or through the use of "opaque" entities  of
>> various types (i.e.
>> elements, attributes, etc.).
>>  However, the semantics of the constructs used in such a  process are
>> exactly the same as
>> their semantics in the  executable context. Addionally, an abstract
>> process is  required
>> to be syntactically valid using the executable  schema extended with
>> the opaque entities.
>>  [4]  The omitted operational details may be added anywhere,
>>  by or when mapping an abstract process to a fully executable 
>> artifact. In addition, if
>> the points of the omitted  operational details are specified through
>> the use of opaque
>>  entities, then these placeholders are replaced with other  concrete
>> entities in any
>> executable artifact that corresponds  to the abstract process using
>> such opaque entities.
>>  [5]  Abstract processes say nothing about *how* concretized, 
>> executable realizations of
>> them should be implemented (ie:  language, platform, etc) (analogy to
>> WSDL). Nor do they
>> imply  a relationship(s) with any such realizations.
>> Proposal for issue 107:
>>  Language extensions required for abstract processes
>>  The language extensions consist of opaque 'placeholders'
>>  whose functions are explained below:
>>  [1]  Opaque expressions- Needed in particular for opaque  assignment,
>> opaque transition
>> conditions, opaque query  expression. Opaque assignment is used for
>> capturing variable
>>  creation/modification in a yet-to-be-concretized mechanism/fashion.
>>  [2]  Opaque activities- Hide a concrete BPEL activity, such
>>  as a structured activity, a lifecycle activity (ie.
>>  receive-start) or even just an "empty". They may also be used  as a
>> source or a target of
>> control links.
>>  [3]  Opaque attributes- Hide a concrete BPEL attribute. For  example
>> in invoke, receive
>> or reply activities opaque  attributes are specifying that variables
>> need to be filled in
>>  by or when mapping the partial process specification to a fully
>> executable artifact.
>> Peter
>> ------------------------------------------
>> Peter Furniss
>> Chief Scientist, Choreology Ltd
>> web: http://www.choreology.com
>> email: peter.furniss@choreology.com
>> phone: +44 870 739 0066
>> mobile: +44 7951 536168
>> Choreology Anti virus scan completed
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