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

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

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"
>           ...
> 
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> 
> php.
>