RE: [wsbpel] Issue 6 - Proposal for vote

["Satish Thatte" <satisht@microsoft.com>]

Peter,

Yes to the semantics of "cancelled".

The scope that fires <complete ../> is the first to be prematurely
completed, and in fact the only one when the minimal form <complete/> is
used (scope name omitted).

Satish
 

-----Original Message-----
From: Furniss, Peter [mailto:Peter.Furniss@choreology.com] 
Sent: Monday, September 20, 2004 4:05 AM
To: Satish Thatte; wsbpeltc
Subject: RE: [wsbpel] Issue 6 - Proposal for vote

I think I like this.

But isn't the nested scope that fires the <complete
scope="ancestralScope"> still itself incomplete ? So it will get caught
in the cancellation. Or is it specially protected -  so "all
concurrently running activities in that scope will be cancelled" should
have added something like "except for the nested scope which generated
the completion (at any depth of nesting)". Otherwise the successful
nested scope will get cancelled just like its unsuccessful siblings.

(I'm assuming "cancelled" is following the rough consensus emerging on
issue 135 as a rename of forcibly terminated)

Peter

> -----Original Message-----
> From: Satish Thatte [mailto:satisht@microsoft.com]
> Sent: 17 September 2004 18:20
> To: wsbpeltc
> Subject: [wsbpel] Issue 6 - Proposal for vote
> 
> 
> Please note that this proposal also subsumes Issue 142 as the examples

> show.  Also note that everyone involved in the discussion of Issue 6 
> has not had time to comment on the merits of this proposal relative to

> alternatives.  I am putting it up so that we can discuss it at the 
> F2F. Early comments are always welcome.
> 
> Proposal for resolution of both Issues 6 and 142.
> 
> Define a new activity of the form <complete scope="ScopeName"?>.  The 
> execution of this activity will cause premature but successful 
> completion of all enclosing scopes upto and including the scope named 
> in the optional scope attribute.  In case the attribute is omitted, 
> the default value of the attribute is the name of the nearest 
> enclosing scope.
> 
> In case of premature but successful completion of a scope, all 
> concurrently running activities in that scope will be cancelled.  A 
> scope may optionally have a completion handler.
>  A completion handler is syntactically similar to a compensation 
> handler (no parameters).  In case of premature but successful 
> completion of a scope the completion handler is run if present.  The 
> default completion handler does nothing. The completion handler is run

> in the context of the scope it is attached to, hence may use variables

> and partnerLinks defined within that scope.
> 
> The behavior of the completionHandler is treated as part of the 
> "forward work" of the scope.  Thus all fault handlers for a scope are 
> still available while the completion handler for that scope is 
> running.  In case of a fault in a completion handler, the behavior is 
> identical to the occurrence of a fault in the main body of the scope.
> 
> Question: can the <complete/> activity be used in a completionHandler?

> Or perhaps only in the named (final) one in a completion process?
> 
> Rationale:  This proposal defines a "break-like" feature following the

> patterns of the rest of our interrupt machinery, e.g., fault and 
> cancel handlers.  It is possible to use this to build declarative 
> macros for a variety of purposes including the various flow-based 
> features that were proposed.
> 
> Examples:
> 
> Break: 
> 
> Wrap a while loop with a scope S and use <complete scope="S"/> to 
> break from the loop.
> 
> Continue:  
> 
> Wrap the body of a while loop with a scope S and use <complete 
> scope="S"/> to continue with the next iteration of the loop.
> 
> At least N of M activities in a flow:
> 
> <scope name="N-of-M">
>   <completionHandler>
>   </completionHandler>
>   <flow>
>    ..
>      <sequence>
>        <original "activity that counts">
>        <update completion count variable V>
>        <switch>
>          <case using V, N out of M done?>
>            <complete scope="N-of-M"/>
>          </case>
>        </switch>
>      </sequence>
>     ..other activities in flow
>   </flow>
> </scope>
> 
> Can we do exactly N of M using an isolation scope for the switch?
> 
> Satish
> 
> 
> 
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>