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Subject: Re: [ebxml-cppa] Re: [ebxml-msg] Arvola's SyncReply issues


Tony:
 
Sorry for the inappropriate choice of word. I think "SHALL NOT" is more appropriate.
 
Thanks,
-Arvola
----- Original Message -----
From: Tony Weida
Sent: Friday, January 04, 2002 8:23 AM
Subject: Re: [ebxml-cppa] Re: [ebxml-msg] Arvola's SyncReply issues

Arvola,
 
An inline question prefixed with TW: ...
 
Thanks,
Tony
----- Original Message -----
Sent: Thursday, January 03, 2002 1:13 PM
Subject: [ebxml-cppa] Re: [ebxml-msg] Arvola's SyncReply issues

Doug:
 
There was a CPP/A conference call this morning. I brought up the issue regarding syncReplyMode when an asynchronous communication protocol is being used. The team is agreeable to removing the following statement from the 1.1 CPP/A spec:
 
"If the delivery channel identifies a transport protocol that has no synchronous capabilities (such as SMTP) and the Characteristics element has a syncReplyMode attribute with a value other than "none", a response SHALL contain the same content as if the transport protocol did support synchronous responses."
 
to ensure that it is in alignment with the 1.1 Messaging spec. Instead, some clarification language will be added to indicate that a syncReplyMode other than "none" should not be used
 
TW: Do you mean SHOULD NOT (because the result would be unspecified) or SHALL NOT?
 
when the delivery channel uses an asynchronous communication protocol.
 
Regards,
-Arvola
----- Original Message -----
Sent: Wednesday, January 02, 2002 6:43 PM
Subject: Re: [ebxml-msg] Arvola's SyncReply issues

Doug:
 
Please see my comments inline.
 
Regards,
-Arvola
----- Original Message -----
Sent: Wednesday, January 02, 2002 1:48 PM
Subject: [ebxml-msg] Arvola's SyncReply issues

Arvola,
 
I've snipped out a few of your comments that centre on the SyncReply element and embedded a few comments below.  Hopefully, this will move us quickly towards resolving your questions.
 
thanx,
    doug
 
----- Original Message -----
Sent: Wednesday, 02 January 2002 12:33
Subject: Re: [ebxml-msg] Messaging Spec v1.092

...
 
6. Line 1412: I like to point out that a SyncReply element is not compatible with an AckRequested element that is targeted at the next MSH.
I'm not sure why you're of this opinion.  Why couldn't the next MSH synchronously reply with an Acknowledgment element (after it's persisted the incoming message, of course)?
 
<ac>
The From Party MSH expects a synchronous response from the To Party MSH.  On the other hand, if the intermediary MSH returns the intermediate Acknowledgment synchronously after it has persisted the message, and then closes the HTTP connection (prior to forwarding the message), then how can the response from the To Party MSH be returned synchronously to the From Party MSH?
</ac>
 
12. Line 1591: I think it may be problematical for the recipient to do duplicate elimination when no DuplicateElimination element is present. What happens if SyncReply is present and AckRequested is not present. If the incoming message is not passed on to the application, should any reply be returned to the sender?
The DuplicateElimination semantics are described rather clearly in the specification.  The answer to your question is that the synchronous reply must contain the first response to the duplicate message.  The receiver application might not hear about the duplicate but the will get the same answer back as the first time.
 
<ac>
You are correct. I was confused by the statement on line 1788: "A Receiving MSH node is not participating in the reliable messaging protocol for a received message if the message either does not contain an AckRequested element, or ..." I think there are actually four aspects of reliable messaging behavior: (1) persisting the sent message and retry on the part of the sender when an Acknowledgment is not returned in time; (2) returning an Acknowledgment message by the receiver; (3) persisting the received message to allow duplicate elimination by the receiver; (4) automatic returning of the first response message without forwarding the message to the application when a duplicate message is received. (1) and (2) are triggered by the AckRequested element. (3) and (4) are triggered by the DuplicateElimination element, or if the receiver decides to do duplicate elimination in spite of the absence of a DuplicateElimination element in the incoming message. Line 1589 needs to clarify what adopting a reliable messaging behavior really means (really (3) and (4)). In the paragraph starting on line 1591, it will be helpful to qualify "although elimination of duplicates is still allowed" to mean that (3) and (4) are to be done.
</ac>
 
20. Line 1733 and line 1738: These two bullet points assume that syncReplyMode in the CPA is not used with an asynchronous communication channel. This is in conflict with the 1.0 CPP/A spec statement quoted in item 15 above. I think this is a minor technical issue that may require some discussion.
Would this be resolved by (more correctly) referencing the syncReplyMode semantics in the CPP/A 1.1 specification?  If not, we still have a discrepancy between the two specifications and that should be resolved as soon as possible.  The CPP/A 1.0 specification may have some vestiges of the "bundling" semantics I've mentioned before (using syncReplyMode to describe which signals may be bundled with the application response).  Those semantics apply equally to synchronous and asynchronous channels.  The current SyncReply MSH semantics are all about what signals must appear in the synchronous response over a synchronous channel.
It's not up to the MSH to determine how later business responses might be bundled with business signals and asynchronous channels are therefore not relevant.  Of course, the current description of an MSH doesn't provide a way to describe expectations around bundling of business responses and signals with MSH signals like the Acknowledgment element over an asynchronous channel.  2.0 issue?
 
<ac>
I think the simplest solution may be to request the CPP/A team to strike out from the 1.1 spec the following sentence: "If the delivery channel identifies a transport protocol that has no synchronous capabilities (such as SMTP) and the Characteristics element has a syncReplyMode attribute with a value other than "none", a response SHALL contain the same content as if the transport protocol did support synchronous responses." which contradicts the statement on line 1625: "The SyncReplyMode parameter from the CPA is used only if the data communications protocol is synchronous (e.g. HTTP)." We can defer the bundling issue for asynchronous communications protocols until the 2.0 versions of the MSG and CPP/A specs.
</ac>
 
...
 


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