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Subject: RE: [wsbpel] Issue - 297 - Does correlation require a propertyAlias withmessageType attribute?


+1 to this issue.

We've discussed this question while the chapter 15 review, too (in 15.2.2
there is a receive referencing an element-typed variable but there's only a
message-typed propertyAlias for the input message of the used operation).
The only paragraph we have found which indicates (but does not say it
explicitly) that the example is correct, is the one you'd like to add the
clarification. It's currently really hard to find this paragraph, because
there is no normative MUST regarding the propertyAlias <-> correlation
relationship, and additionally it's hard to find out what is meant by the
current wording. There are other paragraphs in 7.3 which might be
interpreted that an element-typed propertyAlias is expected:

"The first bpel:propertyAlias defines a named property tns:taxpayerNumber
as an alias for a location in the identification part of the message type
txmsg:taxpayerInfoMsg.

The second bpel:propertyAlias provides a second definition for the same
named property tns:taxpayerNumber but this time as an alias for a location
inside of the element txtyp:taxPayerInfoElem.

The presence of both aliases means that it is possible to retrieve the
social security number from both a variable holding a message of
messageType txmsg:taxpayerInfo as well as an element defined using
txtyp:taxPayerInfoElem."

But the referenced paragraph in 9.2 says that for correlation the message
have to be used for retrieving the correlation values and not the variable
with which the message is constructed. Therefore it indicates that a
message-typed propertyAlias is expected. Your proposal makes this very
clear now.

The static analysis list should be updated accordingly because violation of
this rule can be detected while static analysis. Maybe the proposal can be
changed  to:

      Observe that in order to retrieve correlation values from a message,
      a processor MUST apply a <propertyAlias> with a messageType value
      that matches the QName of the message. This constraint MUST be
      statically enforced. In the case in which the application of the
      <propertyAlias> results in a response that contains anything other
      than exactly one information item and/or a collection of Character
      Information Items then a bpel:selectionFailure fault MUST be thrown.

Best regards/Mit freundlichen Grüßen,

       Thomas Schulze



                                                                       
             "Mark Ford"                                               
             <mark.ford@active                                         
             -endpoints.com>                                            To
                                       <wsbpel@lists.oasis-open.org>   
             10.06.2006 18:00                                           cc
                                                                       
                                                                   Subject
                                       RE: [wsbpel] Issue - 297 - Does 
                                       correlation require a propertyAlias
                                       with messageType attribute?     
                                                                       
                                                                       
                                                                       
                                                                       
                                                                       
                                                                       




I discussed this with Chris Keller last week and he seemed to recall that
this was already settled by a previous issue. After doing a little research
I found the following issues which touch on this area:

Issue 112: Input/Output Elements on Messaging Activities
http://www.choreology.com/external/WS_BPEL_issues_list.html#Issue112
-- This issue added support for elements on message activities
Issue 145: Properties on Non-Message Variables
http://www.choreology.com/external/WS_BPEL_issues_list.html#Issue145
-- This issue added support for propertyAliases for elements and types. It
does not discuss correlation. Perhaps it was mentioned during the face to
face in Hawthorne?

If the intent was to allow elementType propertyAliases for correlation then
this has not made it into the spec. Does anyone else recall the discussion
or can they point me to another issue that might address this? Lastly, if I
missed a part of the spec that covers this I'd appreciate a pointer to it
as well.

Thanks.



From: ws-bpel issues list editor [mailto:peter.furniss@erebor.co.uk]
Sent: Saturday, June 10, 2006 11:47 AM
To: wsbpel@lists.oasis-open.org
Subject: [wsbpel] Issue - 297 - Does correlation require a propertyAlias
with messageType attribute?



This issue has been added to the wsbpel issue list with a status of
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will remain as "received".


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include an issue when it is announced, is available at this constant URL.
Issue - 297 - Does correlation require a propertyAlias with messageType
attribute?


Status: received
Date added: 10 Jun 2006
Date submitted: 09 June 2006
Submitter: Mark Ford
Description: I'd like a clarification as to the use of a propertyAlias for
message correlation. My reading is that the spec requires a propertyAlias
with a messageType in order to extract values for correlation. In cases
where an activity like a <receive> uses an elementType variable for its
data the spec explains that an anonymous temporary WSDL message variable is
created for the data and its single part is used to populate the element
variable on the <receive>. The same wording (anonymous temporary WSDL
message variable) is used to explain <fromPart> and <toPart> behavior.


If the intent is to allow propertyAlias with elementType then we would need
to define which propertyAlias would be used in the case that there was a
messageType and an elementType since they could have different queries.


If the intent is to require a propertyAlias with messageType then some
additional text to Section 9.2 could make this explicit.
Submitter's proposal:


In Section 9.2, change


--- from ---
      Observe that in order to retrieve correlation values from a message,
      a processor needs to apply a particular <propertyAlias> to the
      message. In the case in which the application of the <propertyAlias>
      results in a response that contains anything other than exactly one
      information item and/or a collection of Character Information Items
      then a bpel:selectionFailure fault MUST be thrown.


--- to ---
      Observe that in order to retrieve correlation values from a message,
      a processor MUST apply a <propertyAlias> with a messageType value
      that matches the QName of the message. In the case in which the
      application of the <propertyAlias> results in a response that
      contains anything other than exactly one information item and/or a
      collection of Character Information Items then a
      bpel:selectionFailure fault MUST be thrown.



Changes: 10 Jun 2006 - new issue



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