Auto Complete Copy Destination (L-Value)
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                 Key: ODE-371
                 URL: https://issues.apache.org/jira/browse/ODE-371
             Project: ODE
          Issue Type: New Feature
    Affects Versions: 1.2
         Environment: platform-independent
            Reporter: Karthick Sankarachary
             Fix For: 1.3


A lot of times, users expect the <copy> operation in a WS-BPEL assign activity 
to behave such that the path specified by the destination ("to-spec") is 
automatically created, if it doesn't already exist. By default, if the to-spec 
used within a <copy> operation does not select exactly one XML information item 
during execution, then the standard fault bpel:selectionFailure is thrown (as 
mandated by the spec).

To override this default behavior, we introduce a insertMissingToData attribute 
in the <copy> operation, which if it is set to "yes", will instruct the runtime 
to complete the (XPath) L-value specified by the to-spec, if no items were 
selected. For the sake of simplicity, we will complete the to-spec if and only 
if:
a) It's a path expression whose steps are separated by "/", and
b) Its steps have an axis, which is either "child" or "attribute", and
c) Its steps have no following predicates, and
d) Its steps test the name of a node,  without the use of wildcards.

Formally, the grammar of the to-spec, for which auto-complete is enabled, may 
be defined in terms of these productions:
    PathExpr              ::=    ("/" RelativePathExpr?) | RelativePathExpr
    RelativePathExpr      ::=    ForwardStep (("/" ) ForwardStep)*
    ForwardStep           ::=    (ForwardAxis QName) | AbbrevForwardStep
    AbbrevForwardStep     ::=    "@"? QName
    ForwardAxis           ::=    ("child" "::") | ("attribute" "::")

The example below illustrates the use of the insertMissingToData attribute. 
Let's say that the variable "response" is uninitialized. In that case, the 
first <copy> operation will fail, whereas the second one will succeed.

    <copy>
        
<from>$request.requestMessageData/typeIndicators/types:indicatorTwo</from>
        <to>$response/typeIndicators/types:indicatorTwo</to>
    </copy>

    <copy insertMissingToData="yes">
        
<from>$request.requestMessageData/typeIndicators/types:indicatorTwo</from>
        <to>$response/typeIndicators/child::types:indicatorTwo</to>
     </copy>

Best Regards,
Karthick Sankarachary

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