RE: [wsbpel] the last paragraph of "Default Compensation Order" section

[Simon D Moser <SMOSER@de.ibm.com>]

Peter,

I think in your given example they are actually the same. However, problems
occur when there are control dependencies between the scopes because nested
activities are linked introducing such a control dependency. I think the
key point of the text below is: You do not need to compensate in depth
first, but, if it is possible, you can parallelize the compensation order
if the rules are not contradicted ?!


Cheers
/Simon
--------------------------------------------------
Simon Daniel Moser, M.Eng.
Business Process Solutions Development 1
IBM Boeblingen Laboratory
Schoenaicherstr. 220, 01/086
D - 71032 Boeblingen
Tel.: +49 - 7031 - 164304
IP Telephone Number (ITN): 39204304
email: smoser@de.ibm.com

Rule of thumb #3459835478: when you find yourself typing/copying the same
thing more than twice in a row, redesign or re-implement. No excuse
possible.




                                                                           
             "Peter Furniss"                                               
             <peter.furniss@er                                             
             ebor.co.uk>                                                To 
                                       "Alex Yiu" <alex.yiu@oracle.com>,   
             05/04/2006 10:21          "wsbpeltc"                          
             PM                        <wsbpel@lists.oasis-open.org>       
                                                                        cc 
                                                                           
                                                                   Subject 
                                       RE: [wsbpel] the last paragraph of  
                                       "Default Compensation Order"        
                                       section                             
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




I'm having difficulty sorting out what this means - nothing particularly to
do with transactionality, just whether two orderings are consistent

given a structure of scopes (with flows)
A
    B
        C
    D
        E
        F

and start-  -end times for the scopes

a-  b-  d- c- e- f- -e -c -f -d -b FAULT

then showing the start end of the compensation handlers, doesn't depth
first do
  b- c- -c -b d- f- -f e- -e -d

but strict reverse is

oh - exactly the same (since I can't complete B.compensationHandler without
doing C.compensationHandler.

How about adding at the end of the consistent sentence, and putting "would"
in the last:

"The default compensation order mandated by the rules here is consistent
with strict reverse order of completion within scopes at one level. Strict
reverse order of completion applied to compensation
of all scopes may be not in depth-first order and would require
interleaving of nested
compensations across peer scopes, which is not supported by this
specification.

Peter

From: Alex Yiu [mailto:alex.yiu@oracle.com]
Sent: 04 May 2006 07:55
To: wsbpeltc
Cc: Alex Yiu
Subject: [wsbpel] the last paragraph of "Default Compensation Order"
section


In the last paragraph of "Default Compensation Order" section, we have
seemingly have two phrases that are seemingly difficult to be jelled
together:
"... Rule 2 is to permit a depth-first traversal ..." and
"default compensation order mandated by the rules here is consistent with
strict reverse order of completion, but not in depth-first order ..."

Here is an attempt to smooth this paragraph out:
----------------------
An effect of Rule 2 is to permit a depth-first traversal of the lexical
scope tree for default
compensation, respecting the control dependency relation among peer scopes
as dictated
by Rule 1. Since depth-first order implies that such compensation is only
dependent on
the compensation of its nested scopes, default compensation order can be
easily defined.
The default compensation order mandated by the rules here is consistent
with strict
reverse order of completion. Strict reverse order of completion applied to
compensation
of all scopes may be not in depth-first order and require interleaving of
nested
compensations across peer scopes, which is not supported by this
specification.
----------------------

(I attached the PDF and DOC version as well).
Let's see whether this text is accepted tomorrow.


Regards,
Alex Yiu