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RE: Clarifying exchange type

From: Martin Chapman <martin.chapman@oracle.com>
Date: Thu, 26 Oct 2006 22:18:41 +0100
To: "'Gary Brown'" <gary@pi4tech.com>, "'WS-Choreography List'" <public-ws-chor@w3.org>
Message-ID: <006001c6f944$50add620$9d41908d@ie.oracle.com>

But nobody uses notifications, so doubt if one will ever be sent!
Also ws-addressing can be used to correlate a response with a request using
message-id.


Martin.

>-----Original Message-----
>From: public-ws-chor-request@w3.org 
>[mailto:public-ws-chor-request@w3.org] On Behalf Of Gary Brown
>Sent: Tuesday, October 24, 2006 2:18 PM
>To: 'WS-Choreography List'
>Subject: Clarifying exchange type
>
>
>
>Hi
>
>Currently the 'exchange' within an 'interaction' can have an action 
>attribute with the values:
>
>"Within the |exchange| element, the attribute |action| specifies the 
>direction of the information exchanged in the interaction:
>
>    *
>
>      When the |action| attribute is set to "request", then the
>      information exchange happens from the 'from' roleType to the 'to'
>      roleType
>
>    *
>
>      When the |action| attribute is set to "respond", then the
>      information exchange happens from the 'to' roleType to the 'from'
>      roleType"
>
>
>Where a request and response exchange are separated into different 
>interactions, to enable intervening activities to be described, it 
>requires the implementation to correlate the response exchange 
>with the 
>request exchange to determine they are part of a request-response MEP.
>
>Although in most situations, the use of operation names should support 
>the correlation of the responses with appropriate requests, 
>there may be 
>some situations where a response exchange that actually represents a 
>notification may be incorrectly associated with a preceding request. 
>This is because the action type for a notification exchange would also 
>be 'respond'.
>
>Therefore, although the chance of a notification exchange having the 
>same operation name as a preceding request is remote, it is not 
>forbidden, and therefore for clarity it would be useful to add a third 
>exchange action type called "notify".
>
>This would enable better static validation as it will now be 
>clear what 
>each exchange represents. For example, if an exchange is defined as a 
>'respond' but no request precedes it, then this can be flagged as an 
>error. Currently the assumption would be that it is a 
>notification, and 
>this would be silently ignored.
>
>If the change is acceptable, then the following updates are 
>required in 
>section 6.2.3:
>
>1) Modify second bullet point above:
>From:
>
>    *
>
>      When the |action| attribute is set to "respond", then the
>      information exchange happens from the 'to' roleType to the 'from'
>      roleType"
>
>To:
>
>    *
>
>      When the |action| attribute is set to "respond", then the
>      information exchange happens from the 'to' roleType to the 'from'
>      roleType" and the exchange MUST be associated directly or
>      indirectly with a preceding exchange of action type "request" for
>      the same operation and channel
>
>
>2) Additional bullet point on text above:
>
>    *
>
>      When the |action| attribute is set to "notify", then the
>      information exchange happens from the 'to' roleType to the 'from'
>      roleType"
>
>
>
>3) Following the para that starts "The OPTIONAL record element....."
>
>From:
>"When the |action| element is set to "response", then the recordings 
>specified within the |source| and the |target| elements MUST occur at 
>the 'to' roleType for the send and at the 'from' roleType for 
>the receive"
>To:
>"When the |action| element is set to "respond" or "notify", then the 
>recordings specified within the |source| and the |target| 
>elements MUST 
>occur at the 'to' roleType for the send and at the 'from' roleType for 
>the receive"
>
>
>Regards
>Gary
>
>
>
>
>
Received on Thursday, 26 October 2006 21:19:22 GMT

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