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Bug 1099 - Specify that the evaluation of the guard expression is done in a fixed order
Summary: Specify that the evaluation of the guard expression is done in a fixed order
Status: CLOSED FIXED
Alias: None
Product: WS Choreography
Classification: Unclassified
Component: Last Call Comment: Confirmed Closed (show other bugs)
Version: unspecified
Hardware: PC Linux
: P2 normal
Target Milestone: --
Assignee: Martin Chapman
QA Contact: Martin Chapman
URL: http://lists.w3.org/Archives/Public/p...
Whiteboard:
Keywords:
Depends on: 999
Blocks:
  Show dependency treegraph
 
Reported: 2005-02-07 19:08 UTC by Greg Ritzinger
Modified: 2005-09-28 21:44 UTC (History)
0 users

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Description Greg Ritzinger 2005-02-07 19:08:12 UTC
*2.4.6. Overall on workunits (1).

To have a clear semantics of guards, it is better to specify that the 
evaluation of the guard expression is done in a fixed order (may be
better to specify this explicitly in the CDL-function section or 
in an "expression" section). 

Reasons: If not, prediction of behaviours become hard; flow check 
         becomes hard; can lead to livelock/deadlock easily.
Comment 1 Martin Chapman 2005-02-15 20:44:17 UTC
agreed on con call 15-feb-05:

needs discussion, reklated to tony's short circuit evalution issue
Comment 2 Martin Chapman 2005-03-08 10:41:06 UTC
Discussed at feb-mar 05 f2f:

http://lists.w3.org/Archives/Member/member-ws-chor/2005Mar/att-
0001/Ws_Chor_f2f__Feb-Mar_2005_-0.txt

Use Xpath rules of left to right evaluation.
Comment 3 Martin Chapman 2005-03-08 11:02:36 UTC
add note to spec to say use xpath evaluation ordering
Comment 4 Martin Chapman 2005-05-10 16:44:46 UTC
Kohei has been informed of the group's decision [1] and we are 
awaiting 
confirmation. Category changed to LCC: Closed.

[1] http://lists.w3.org/Archives/Public/public-ws-chor-
comments/2005May/0017.html
Comment 5 Martin Chapman 2005-05-13 09:20:02 UTC
Resonse from Kohei:
http://lists.w3.org/Archives/Public/public-ws-chor-comments/2005May/0027.html

Hi Martin,

My apologies for a late reply. As far as XPath decides a unique evaluation 
order, as it currently does, this is acceptable. I hope we can make it doubly 
clear by adding:

  By this we guarantee a unique order in the way expressions are evaluated,
  i.e. from the left to the right.

This is just to make clear what is the intended behaviour.

Best wishes,

kohei

EDITORS PLEASE CONFIRM.
Comment 6 Greg Ritzinger 2005-05-27 13:50:23 UTC
Refer to changes made for issue 999 which cover this issue as well.
Comment 7 Martin Chapman 2005-09-28 21:44:13 UTC
the text is in the spec do close confirm.