Re: Need to change Service and Action for Errors,Delivery Receipts etc.

[Arvola Chan <arvola@tibco.com>]

David:

 

I am of the opinion that the DeliveryReceipt element should be used by the ToParty MSH to inform the FromParty MSH that a reliable message has been received. Therefore, it is moot as to which application needs to be notified when a standalone message is received containing a single DeliveryReceipt element (because it is really intended for the sending MSH). It is the non-arrival of a DeliveryReceipt that requries the MSH to notify the application. In this case, it must rely on persistent information to determine the application service that must be notified. This is one point that the spec needs to clarify.

 

By the way, I find the reliable messaging section in 0.93 version of the TRP spec

 

http://lists.ebxml.org/archives/ebxml-transport/200102/msg00019.html

 

much more logical than the one in the 1.0 spec. At least, it explicitly covers the scenario of multi-hop reliable messaging and talks about the possibility of reliable messaging with or without intermediary acks. In particular, it distinguishes two types of acknowledgements, one used by intermediary MSHs to the previous hop MSH and the other used by the ToParty MSH to the FromParty MSH. I am curious as to how RM ends up in the current broken state in the 1.0 spec.

 

I think end to end acknowledgement is always needed to support reliable messaging, so it is unnecessary to explicitly set deliveryReceiptRequested to true, it should always be implied by deliverySemantics of OnceAndOnlyOnce. On the other hand, if intermediary acks are optional, then ackRequested needs to be an explicit attribute at the QOS level and it should apply to all intermediaries. When an intermediary uses non ebXML reliable messaging methods that still guarantees delivery, then ackRequested simply does not apply to such intermediaries.

 

I agree with you that the problem is more serious for error messages. In the case of the RosettaNet message header, both the from service and the to service are included. Therefore, in case of errors, it is easy to figure out which service at the sender should be notified. I am in favor of your proposal to add the from service to the ebXML message header.

 

Thanks,

-Arvola

-----Original Message-----
From: Burdett, David <david.burdett@commerceone.com>
To: 'Arvola Chan' <arvola@tibco.com>; 'Dr Crawford' <catcraw@us.ibm.com>; ebxml-msg@lists.oasis-open.org <ebxml-msg@lists.oasis-open.org>
Date: Thursday, August 09, 2001 10:29 AM
Subject: T2: Need to change Service and Action for Errors, Delivery Receipts etc.

Arvola

 

I agree that the spec is quite specific. However I think that having just one value for Service and Action for a Delivery Receipt makes it hard a MSH which receives a Delivery Receipt to work out which application to notify. For normal messages, Service and Action contain some useful name, e.g Service=SupplierOrderManagement, Action=NewPurchase order. This can be used to route the message to the application that supports OrderManagement.

 

On a Delivery Receipt, Service contains "uri:www.ebXML.org/messageService" and Action "DeliveryReceipt" as you quote below and the MSH is given no clue on which application to forward the message to.

 

This means that the MSH has to look up the original message sent to work out where the DR was sent to.

 

There is an IDENTICAL problem with Error Messages as the MSH will not know which the application to forward the message to. This time though, it is worse as the message may not have been saved if it was sent with RM as BestEffort. If we don't change the spec then a Sending MSH will have to PERSIST ALL MESSAGES whether sent reliably or not so that they can work out which applicatioon to notify if there is an error.

 

The better alternative I propose is to make Action hold all the information, e.g.

    Action =uri:www.ebXML.org/messageService/MessageError

 

Then Service could contain "BuyerOrderManagement" so that the MSH could work out which application to notify of the error. However this requires that you know what to put in the Service when an error or other similar message is returned to the sender of a message. To solve this you also need to specify the Sending "From Service" in the original message.

 

Thoughts?

 

David

-----Original Message-----
From: Arvola Chan [mailto:arvola@tibco.com]
Sent: Wednesday, August 08, 2001 6:59 PM
To: Burdett, David; 'Dr Crawford'; ebxml-msg@lists.oasis-open.org
Subject: Re: T2: Reliable Messaging (point-to-point)

Sorry for the delayed response. I was tied up the last couple of days attending to some personal matters.

 

To answer Cait's original question about the Service and Action elements that should be used when a message containing a DeliveryReceipt element is to be sent not in conjunction with any business level reply, the following excerpt from the 1.0 spec clearly states:

If there are no errors in the message received and a DeliveryReceipt is being sent on its own, not as part 848

of message containing payload data, then the Service and Action MUST be set as follows: 849

· the Service element MUST be set to uri:www.ebXML.org/messageService/ 850

· the Action element MUST be set to DeliveryReceipt 851

Unfortunately, the above information is located in section 8.4.7.1 deliveyReceiptRequested attribute, rather than in section 8.14 DeliveryReceipt element.

 

I believe the spec is currently quite specific about the Service and Action elements to use when Acknowledgement, DeliveryReceipt, Error, StatusRequest, StatusResponse, and Ping elements are sent on their own (not in conjunction with business payloads).

 

-Arvola

 

-----Original Message-----
From: Burdett, David <david.burdett@commerceone.com>
To: 'Dr Crawford' <catcraw@us.ibm.com>; ebxml-msg@lists.oasis-open.org <ebxml-msg@lists.oasis-open.org>
Date: Monday, August 06, 2001 6:39 PM
Subject: RE: T2: Reliable Messaging (point-to-point)

>I think that this is a bug in the spec.
>

 

>To solve this problem I think we should include in every message that is
>sent, an identifier for Service that is sending it. You can then use this
>Service when returning a message if there is no business process specific
>one to use instead. You would then use the Action element to identify why
>the message is being sent.
>
>If we make this approach the rule for returning errors, for example, then it
>fixes the problem that a MSH does not know which application it should
>notify if the original message was not persisted (which it shouldn't be if
>it was not sent reliably).
>
>I also think we should follow the same approach for the Message Status and
>Ping transactions for the same reasons.
>
>Thoughts?
>
>David
>
>-----Original Message-----
>From: Dr Crawford [mailto:catcraw@us.ibm.com]
>Sent: Monday, August 06, 2001 8:11 AM
>To: ebxml-msg@lists.oasis-open.org
>Subject: T2: Reliable Messaging (point-to-point)
>
>
>
>
>I have a comments/questions regarding POINT-TO-POINT reliable messaging
>implementation for ebXML MS 1.0.
>
>First, lets assume that Party A is sending a message reliably -- that the
>deliverySemantics have been set to OnceAndOnlyOnce and
>deliveryReceiptRequested to Unsigned (I don't think that Signed/Unsigned
>makes a difference for the example, actually) in the QualityOfService
>element in the MessageHeader.  I am sending this message w/out
>intermediaries, so I am not making use of the Via or Acknowledgment
>elements, although I am populating the TraceHeader element as appropriate.
>
>Now, Party B receives the message.  Now assume that there is NO REPLY from
>the application.  Party B is required to send an "Acknowledgement Message"
>(section 10.3.2) which at a minimum has a MessageData element with a
>RefToMessageId of the received message.  Since a deliveryReceipt is also
>requested, the MSH must also generate the DeliveryReceipt element in the
>ack message.  My question concerns the service and action elements of this
>ack.  Clearly, as there is no business-level reply, the service and action
>should not reflect any business or application level service & action.  In
>section 10.3.3, the spec says that if an Acknowledgment element is being
>sent on its own then service MUST be set to:
>uri:www.ebxml.org/messageService and action MUST be set to Acknowledgment.
>What is the equivalent service/action for a DeliveryReceipt element being
>sent on its own?? (as set in the MessageHeader element for this ack
>message)??  Is this described in the CPP/BPSS since this is one of the
>"signals" that need to be processed by the MSH-application interface??
>
>What would happen if the deliveryReceiptRequested was false, but the
>semantics were set to OnceAndOnlyOnce??  The minimal acknowledgement
>required only a RefToMessageId within the MessageData element -- any
>guidelines as to what should be used in the Service and Action elements in
>the MessageHeader?
>
>In general, I think that the Reliable Messaging section should be expanded
>to include the POINT-TO-POINT option where no Via or Acknowledgment
>elements are used, but deliveryReceiptRequested attributes are turned on.
>(i.e. there is no information about whether the reply is sync or not in the
>message header).
>
>Your guidance is greatly appreciated.
>
>Regards,
>Cait
>
>Cait Crawford
>B2B Integration
>IBM Research
>Hawthorne, NY
>catcraw@us.ibm.COM
>
>
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