RE: [wsbpel] Resolution to issue 10 - Implicit compensation Handler

["Yaron Goland" <ygoland@bea.com>]

Hum.... I'm not sure what you mean. I put some thoughts below as to what I
think you might mean but I'm guessing I missed the particular scenario you
are discussing. Could you please expand on your point about custom handlers
not being able to do what default handlers can do?

	Thanks,

			Yaron

P.S. The default compensation handler has two magical abilities - it can
compensate all sub-scopes even if they aren't named and it can do so in the
reverse order in which they were created (with some sort of tie breaking
algorithm).

For a custom compensation handler to replicate the "call compensation on all
sub-scopes' behavior it must be able to find all its sub-scopes which only
requires that they all be named. That is kind of a pain but doesn't seem too
onerous. The spec even provides for the special sub-case where you have a
sub-scope contained in a loop. Section 13.3 says "If a scope being
compensated by name was nested in a loop, the instances of the compensation
handlers in the successive iterations are invoked in reverse order."

So I would say that the custom compensation handlers can safely pass the bar
of 'call compensate on all sub-scopes', you just need to make sure they are
all named.

The second bar, the ability to call compensation handlers in the reverse
order in which they were completed, is impossible to pass for custom
compensation handlers in cases where a flow without links is involved since
it is impossible to know at design time when the flows will finish at run
time. One possible, deeply nasty, solution to this problem is to stick links
into the last activities in the flows so as to force a certain completion
order but I suspect that rather misses the point. I can imagine how we could
solve this problem but it seems like more trouble than it is worth. What's
the use case?

> -----Original Message-----
> From: Satish Thatte [mailto:satisht@microsoft.com]
> Sent: Thursday, December 11, 2003 5:26 PM
> To: ygoland@bea.com; Sid Askary; wsbpel@lists.oasis-open.org
> Subject: RE: [wsbpel] Resolution to issue 10 - Implicit compensation
> Handler
> 
> 
> Sid and Yaron,
> 
> My main concern with my own proposal is the fact that the default
> behavior cannot be achieved with custom handlers, which is a 
> fault in my
> proposal.  Someone (cannot recall who) brought that up during the face
> to face and it gave me pause.  Need to think about that some more.  In
> the mean while let us wait for Peter's comments.
> 
> Satish
> 
> -----Original Message-----
> From: Yaron Goland [mailto:ygoland@bea.com] 
> Sent: Thursday, December 11, 2003 3:42 PM
> To: 'Sid Askary'; wsbpel@lists.oasis-open.org
> Subject: RE: [wsbpel] Resolution to issue 10 - Implicit compensation
> Handler
> 
> +1
> 
> > -----Original Message-----
> > From: Sid Askary [mailto:saskary@nuperus.com]
> > Sent: Tuesday, December 09, 2003 1:46 PM
> > To: wsbpel@lists.oasis-open.org
> > Subject: [wsbpel] Resolution to issue 10 - Implicit 
> > compensation Handler
> > 
> > 
> > Satish,
> > As I said, I think your solution (the reverse temporal order) 
> > is a good one.  I think I have a simple compromise: that we 
> > add a sentence to the effect that 
> > 
> > " Note: Sole reliance on implicit compensation handlers as a 
> > programming construct or as a means of defining default 
> > system behavior is not recommended."
> > 
> > This may address both the "programmatic" (Yaron's) and 
> > default behavior (my own) assumptions.   
> > 
> > Not sure about Peter's concern.
> > 
> > - Sid.
> > 
> > 
> > 
> > To unsubscribe from this mailing list (and be removed from 
> > the roster of the OASIS TC), go to 
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> > ave_workgroup.php.
> > 
> > 
> 
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