That doesn't work if you want to do cascading completions aka named
completions.
-----Original Message-----
From: Yaron Y. Goland [mailto:]
Sent: Thursday, September 30, 2004 11:17 AM
To: Satish Thatte
Cc: wsbpeltc
Subject: Re: completionHandler example
I realize why putting the completion handler logic before the complete
doesn't work but why doesn't putting it after the completion handler
work?
scope
variables
variable name="MessageTrackerVariable"...
sequence
scope wrapper
flow
scope A_end_in_complete_to_wrapper
...
scope B_end_in_complete_to_wrapper
...
scope C_end_in_complete_to_wrapper
...
scope CompletionHandler
(Check MessageTrackerVariable and see if any cleanup is
needed)
Because the exit point of a completed scope is always well defined can't
the completion handler logic be placed after the completed scope?
Yaron
Satish Thatte wrote:
>
>
> Yaron,
>
> During the F2F you asked for a completionHandler example. Here is my
> try with some explanations. Please let me know if this makes sense to
you.
>
>
> Satish
>
>
> The completionHandler is the common process logic required at all
points
> of premature completion within a scope. The only difference between
> copying it just before each occurrence of a <complete/> activity thus
>
>
>
> <sequence>
>
> <completionHandler logic>
>
> <complete/>
>
> </sequence>
>
>
>
> and the proposed completionHandler feature is that the
completionHandler
> logic executes *after* termination of all activities in the
prematurely
> completed scope. Thus it is a pure macro if the prematurely completed
> scope does not contain concurrent activities. Many examples of the
use
> of premature completion, e.g., completion of N out of M activities in
a
> flow, do involve concurrency. Consider a case where M suppliers had
> been contacted concurrently and the process was waiting for
asynchronous
> responses (forgive the use of the word :-)) from them. After at least
N
> of them send responses the scope completes. Suppose the conversation
> with each supplier is wrapped in a scope and a terminationHandler is
> used to inform a supplier whose conversation was forcibly terminated
> that their response is not needed. But perhaps we did not or could
not
> ensure that *exactly* N replies arrive because the race was too tricky
> to control. Thus it is possible that more than N responses arrived.
> The completion handler could detect this situation, pick the N we
really
> want and inform the rest that their responses have been rejected so
that
> we exit the scope cleanly with exactly N accepted responses.
>
