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Posted to user@ode.apache.org by Wenfeng ZHAO <zh...@gmail.com> on 2009/04/06 17:33:24 UTC
Re: Must BPEL complex variable initialization use extension
mechanisms?
Hello Mark,
Thank you for your deteiled reply which solved my confusion completely.
Yes the first choice you pointed out is proper to initialize a complex
variable. I had falsely understood the relation between "literal
variant of copy" and "TII -> EII".
As to my example, the first copy should be:
<copy>
<from><literal>
<svc01:elemB xmlns:svc01="http://example.com/service01.wsdl">
<svc01:elemC/>
</svc01:elemB>
</literal></from>
<to>$_b</to>
</copy>
rather than
<copy>
<from><literal><svc01:elemC
xmlns:svc01="http://example.com/service01.wsdl"/></literal></from>
<to>$_b</to>
</copy>
Hope it helpful to others.
Thanks again.
On Mon, Apr 6, 2009 at 9:49 PM, Ford, Mark <ma...@ll.mit.edu> wrote:
> The BPEL spec only addresses copy operations. As such, the to-spec for the copy operation must result in a target node that exists. A TII -> EII copy operation will never result in the creation of a child element in the target node. The result will be the target element having a single child text node, not an element node.
>
> What you have run into is a valid exception being thrown because your second copy operation is targeting a node that does not exist in the variable $_b. After the first copy operation, the contents of $_b are:
>
> <svc01:elemC/>
>
> You are attempting to copy $_c into a child of $_b that doesn't exist. For example:
>
> <svc01:elemC>
> <svc01:elemC/> <!-- This is the node you're targeting -->
> <scv01:elemC>
>
> The quote from the spec that you referenced pertains to the literal variant of the copy operation. With this variant, the from-spec must produce a single EII or a single TII. In your case, you are producing a single EII which is valid. Therefore it is not a TII -> EII copy operation, it's actually an EII -> EII copy operation.
>
> Your choices are (in no particular order):
>
> * initialize the entire target variable using the complete element in the literal from-spec
> * use extensions to dynamically create missing target nodes
> * use Xquery expressions in the from-spec to construct the complex variable dynamically in a simple EII -> EII copy op to update the whole variable or parts of it.
>
> On 4/6/09 4:19 AM, "ZHAO Wenfeng" <zh...@gmail.com> wrote:
>
> According to WS-BPEL(Version 2.0) specification, it seems that the "TII -> EII" type of copy can be used to initialize a complex variable - at least to create its first children. The section "8.4.2. Replacement Logic of Copy Operations" says(P.70):
> "To replace the destination content:
> If the destination is an EII, all [children] properties (if any) are removed and the source content TII is added as the child of the EII. "
>
> But ODE 2.0 seems not to comply with it because in my case the assignment:
> <copy>
> <from><literal><svc01:elemC xmlns:svc01="http://example.com/service01.wsdl"/></literal></from>
> <to>$_b</to>
> </copy>
> <copy xmlns:svc01="http://example.com/service01.wsdl">
> <from>$_c</from>
> <to>$_b/svc01:elemC</to>
> </copy>
> will incur selectionFailure:
> ERROR - GeronimoLog.error(104) | Assignment Fault: {http://docs.oasis-open.org/w
> sbpel/2.0/process/executable}selectionFailure,lineNo=98,faultExplanation={http:/
> /docs.oasis-open.org/wsbpel/2.0/process/executable}selectionFailure: No results
> for expression: {OXPath10Expression $_b/svc01:elemC}
>
> But alternatively, using the XPath extention fuction insert-as-last-into() provided by ODE, the above initialization can be accomplished.
>
>
> The version of ODE I use is ODE 2.0 Build #87 (2009-1-8 2:25:04). The declaration of the variables is as:
> <variables xmlns:ws0="http://example.com/service01.wsdl">
> ... ...
> <variable name="_a" element="ws0:elemA" />
> <variable name="_b" element="ws0:elemB" />
> <variable name="_c" element="ws0:elemC" />
> <variable name="_a2" element="ws0:elemA2" />
> </variables>
> And the schema is:
> <schema targetNamespace="http://example.com/service01.wsdl"
> xmlns="http://www.w3.org/2001/XMLSchema"
> elementFormDefault="qualified">
> ... ...
> <element name="ResultInfo">
> <complexType>
> <sequence>
> <element name="elemA">
> <complexType>
> <sequence>
> <element name="elemB">
> <complexType>
> <sequence>
> <element name="elemC" type="string" maxOccurs="unbounded"/>
> </sequence>
> </complexType>
> </element>
> </sequence>
> </complexType>
> </element>
> <element name="elemA2" type="string"/>
> </sequence>
> </complexType>
> </element>
> </schema>
> The complete file set is in the attachment.
>
>
> If this disagreement in ODE is not a bug but a intentional design, I guess the reason is that, according to WS-BPEL, even if it is supported, only the first child can be created and the creation of other children must appeal to some extension mechanism. See "8.4 Assignment"(P.62):
> "The fifth from-spec variant returns values as if it were a from-spec that selects the children of the <literal> element in the WS-BPEL source code. [SA00038] The return value MUST be a *single* EII or Text Information Item (TII) only."
>
> Am I right?
>
>
> Thanks & Regards
> Wenfeng
>
>
> ----------
> ZHAO Wenfeng
> http://www.bupt.edu.cn
>
>
>
>
> --
> Mark Ford
> MIT Lincoln Laboratory
> 244 Wood Street
> Lexington MA 02420
> (781) 981-1843
>
Regards
Wenfeng
---------------------
Zhao, Wenfeng
http://www.bupt.edu.cn