Re: [wsbpel] Need for Formalism

[Steve Ross-Talbot <steve@enigmatec.net>]

I'd be interested in any papers that explains how the graph based 
approach of WSFL was combined with the pi-calculus approach that is 
supposed to reflect XLANG.

Cheers

Steve T

On Monday, July 28, 2003, at 08:57  pm, Sid Askary wrote:

> I would like to pose the need for a ”formalism” to the group.  I think 
> we need it.  Here are some of my thoughts.  Let me know what you > think.
>
> When developing a programming language (be it declarative, as in the 
> case of BPEL), there is generally a computation model (reasoned 
> mathematically – as is the case with process calculi) followed by 
> syntax and semantics.
>
> The syntax will usually be accompanied by one or more of the three 
> commonly known complementary formal approaches:
>
> 1)  Denotational semantics: -  Used mainly for requirements, 
> specification correctness, etc.
> -  Concerned with effects - observable behavior (and property) after 
> execution.
>
> 2)  Algebriac Semantics:
> -  Used mainly to reason about the language specification.
> -  Concerned with partial correctness – formulas for pre and post 
> condition states.
>
> 3)  Operational Semantics:
> -  Used mainly for guidelines on implementation.
> -  Concerned with how to execute a program using atomic steps and 
> transition rules.
>
> The above methods are neither always present in a language 
> presentation, nor are they complete.  For instance, “Total 
> correctness” proofs such as deadlocks, abnormal termination, etc. are 
> often ignored.  Nevertheless, they help to reinforce the soundness of 
> the proofs (or claims) by multiple means.
>
> The issue of formalism becomes even more critical when a language is 
> being debated in the context of a standard organization.  And in the 
> case of BPEL specification, although there is a notion of “operational 
> semantics” (albeit not formalized), there are also “distributed”, 
> “concurrent” and “asynchronous” properties that are not formalized – 
> (“intent” and “goals” notwithstanding, as I look forward to reading 
> that upcoming document from the original authors).  Since the BPEL 
> specification is a combination of XLANG and WSPL, what is the combined 
> computational model?
>
> To relegate this question to practical domain is not sufficient.  It 
> is often the case that in practice, such problems are tackled 
> empirically in execution environment where common programming 
> languages (and/or platforms) can simultaneously mask some deficiencies 
> AND highlight others in the specification.  Furthermore, while they 
> may focus on common to perform process/workflow patterns, the 
> implementations do not reflect the causal relationship for 
> stratification of specification as it pertains to certain aspects 
> (i.e. reliance on certain protocols, security, choice of methodology 
> for extraction of expressions, etc.).
>
> Therefore, two additional semantics plus a computational model is 
> needed in order to fully reason about the specification and discuss 
> provability, completeness, liveliness and other relevant properties.  
> I imagine that the original authors have some or all of these 
> constructs and I only ask that they be shared with the group.
>
> Regards,
> Sid Askary
>
>
>
>
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