Re: [wsbpel] Issue - 63 - For Each?

[Alex Yiu <alex.yiu@oracle.com>]

I just would like to mention that the "break" ability may be better considered in a more general context: e.g. a generalized "complete-condition" in the light of Issue 4 / parallel for-each (another suggestion made by Yaron).

Regards,
Alex


Kristofer Agren wrote:

In my opinion, throwing faults to control the normal flow is not the way to
go since breaking out a loop is well-defined action and should not be
treated as an exception to the process flow.

I think introducing a for-each activity is a good idea, but it would be
somewhat crippled without a "break" ability. And if we introduce a "break"
activity, is there any reason why we would not want to be able to use it
with the "while" activity?

Thanks,

Kristofer

-----Original Message-----
From: Yaron Y. Goland [mailto:ygoland@bea.com] 
Sent: Monday, April 12, 2004 1:57 PM
To: Kristofer Agren
Cc: wsbpeltc
Subject: Re: [wsbpel] Issue - 63 - For Each?

Personally I'm o.k. with not introducing a break and instead raising a 
fault but I'm pretty open minded on the issue.

Kristofer Agren wrote:

  

Yaron,

Thank you for the clarification. When applying the "for-each" construct in
the various structured languages where it is supported, it is also fairly
common to use the "break" construct to discontinue the iteration for some
reason. Without a break action, you would be forced to raise a fault to 
stop
the iteration.

Thanks,

Kristofer

-----Original Message-----
From: Yaron Y. Goland [mailto:ygoland@bea.com]
Sent: Friday, April 09, 2004 5:36 PM
To: Kristofer Agren
Cc: wsbpeltc
Subject: Re: [wsbpel] Issue - 63 - For Each?

The syntax I proposed is directly adapted from Issue 13. That is where
we introduced an explicit query element and a local override for the
query language specified on the process element.

        Thanks,
                Yaron

Kristofer Agren wrote:

 >
 >
 > Yaron,
 >
 > I agree with you in that adding a for-each construct, like the one you
have
 > detailed, would both be a good way to solve issue 63 and would also
 > simplify
 > writing BPEL since iterating over a node list is a very common 
scenario. I
 > am just curious why you have added the query as a separate element 
and not
 > an attribute, like the <from> construct for example, and why not use
    

the
  

 > query language that can be specified on the <process> element?
 >
 > Regards,
 >
 > Kristofer
 >
 > -----Original Message-----
 > From: Yaron Y. Goland [mailto:ygoland@bea.com]
 > Sent: Thursday, March 25, 2004 4:17 PM
 > To: wsbpeltc
 > Subject: [wsbpel] Issue - 63 - For Each?
 >
 > The following are thoughts I've had on how we could address issue 63.
 > Although these thoughts are still fairly rough I wanted to release them
 > now because 63 is on the agenda for the F2F. Since these are early
 > thoughts I reserve the right to disavow them at any time.
 >
 > I thought an easy way to provide the feature asked for in 63 is to
 > provide a macro that has proven its utility in numerous structured
 > languages - For Each.
 >
 > I was thinking of a syntax like:
 > <foreach sourceVariable="ncname" part="ncname"? \
 >           iteratorVariableName="ncname" iteratorVariableType="qname"
 >           standard-attributes>
 >     standard-elements
 >     <query language="anyURI">...</query>
 >     activity
 > </foreach>
 >
 > The idea is that the query element would be an expression that
    

generates
  

 > zero or more nodes. Each generated node would be assigned to a local
 > variable whose name is given in iteratorVariableName and whose type is
 > iteratorVariableType. The foreach would then walk through each node one
 > by one in document order. If no nodes are returned then the activity
 > would do nothing.
 >
 > For example:
 > foreach sourceVariable="orderManifest" part="somePart"\
 >          iteratorVariableName="anOrder" iteratorVariableType="b:ar"
 >     query language="http://www.w3.org/TR/1999/REC-xpath-19991116"
 >        ordermanifest/orders
 >     ...
 >
 > Would be a Macro for:
 > scope
 >     variables
 >        variable name="anOrder" type="b:ar"
 >        variable name="currentInstanceNum" type="xs:int"
 >     sequence
 >        assign
 >           copy
 >              from
 >                 "1"
 >              to variable="currentInstanceNum"
 >        while condition="$currentInstanceNum <=\
 >
    

count($orderList/somePart/ordermanifest/orders)"
  

 >           assign
 >              copy
 >                 from variable="orderList" part="somePart"
 >                    query
 >                       "(/ordermanifest/orders)[$currentInstanceNum]"
 >                 to variable="anOrder"
 >           assign
 >              copy
 >                from
 >                   expression
 >                      "$currentInstanceNum+1"
 >                to variable="currentInstanceNum"
 >           ...
 >
 > To unsubscribe from this mailing list (and be removed from the roster
    

of
  

 > the
 > OASIS TC), go to
 >

    

http://www.oasis-open.org/apps/org/workgroup/wsbpel/members/leave_workgroup.

  

 >
 > php.
 >

    

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