RE: [wsbpel] Issue - 297 - Does correlation require a propertyAlias with messageType attribute?

["Mark Ford" <mark.ford@active-endpoints.com>]

You mentioned in the call today that you are in favor of allowing elementType propertyAliases in correlation. My preference is to require a messageType propertyAlias because I read the spec to say that all web service interactions (<receive>, <invoke> ...etc) use a message variable for sending/receiving data. In cases where the activity provides an element variable or no variable at all (i.e. <fromPart> or <toPart>) there is an anonymous WSDL message variable created to send/receive the data. When the current spec refers to correlation it talks about messages, not variables. As such, it seems consistent to require a messageType propertyAlias.

 

If you or others feel strongly that support for elementType attributes is needed then I'd ask that you (or others) look at adding language to handle the following cases:

1) element variable used but elementType propertyAlias not available. Is this an error or does the engine look for a messageType alias?

2) single part message variable used but messageType propertyAlias not available. Does the processor look for a suitable elementType alias?

3) no variable used (<fromPart>, <toPart>). Do we select an elementType or messageType first? What if both are found and they have different <query> expressions? Is that an error?

 

 

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From: Mark Ford [mailto:mark.ford@active-endpoints.com]
Sent: Saturday, June 10, 2006 12:00 PM
To: 'wsbpel@lists.oasis-open.org'
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.

 

 

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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?

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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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