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From "Alex Boisvert" <boisv...@intalio.com>
Subject Re: Variable initialization question...
Date Sun, 29 Jul 2007 01:48:38 GMT
Hi Rich,

On 7/26/07, Rich Taylor <bhamtaylor@gmail.com> wrote:
>
> Possibly silly question about variable initialization.  When you want to
> populate a variable with data do you first need to initialize the variable
> with an empty/skeleton xml structure?


Yes, but only if you're not assigning at the root of the variable content.


 An example of what I mean is below.
>
> If I don't assign a skeleton xml structure to the "output" variable using
> an
> additional "copy"/" from literal" activity, I get the following from Ode
> upon execution:
> Error:
> ERROR [ASSIGN]: Assignment Fault: {
>
> http://docs.oasis-open.org/wsbpel/2.0/process/executable}selectionFailure,lineNo=19
> org.apache.axis2.AxisFault: {
> http://docs.oasis-open.org/wsbpel/2.0/process/executable}selectionFailureNo
> results for expression: {OXPath10Expression /tns:result}
>
> The error makes sense since it's trying to execute an XPath against a
> document that doesn't exist.  However I was thinking the BPEL engine would
> automatically create the blank xml output document for me.   Seems like
> this
> isn't the case.


This doesn't seem to be a good solution because it would only work in the
simplest cases...  You can't always infer the full path from an expression.


Consider, for example, expressions such as:
1) //bar    (all "bar" elements at any level)
2) /foo/bar[2] (the second "bar" element under foo;  what is the first??)
3)  /foo/bar[ text() = 'baz' ]  (using a predicate; what is the rest of the
structure?  how can engine create the content of the element to match the
expression?)
...
and it gets even more hairy with XPath 2.0.


Sorry, I realize this isn't Ode specific.   On an additional note, can
> anyone suggest a good online forum for questions regarding the WSBPEL
> 2.0spec?


Good question!  I'd also like to know if such a forum exist.  Otherwise, I
think this is a good forum.

alex

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