Re: [wsrm] Need to rethink semantics of duplicate elimination behaviour

[Tom Rutt <tom@coastin.com>]

Sunil Kunisetty wrote:

> Tom,
>
> This semantics will be very confusing as it will result in DuplicateMessage
> fault (which indirectly indicates an Ack.) before the actual Ack. itself.
>
But I think this is a consequence of our new semantics of acknowldegment 
awaiting delivery.

If a sender resends a message which is being held wating for a prior 
message, what should
the receiver do?    He is holding the ack to the original http request 
for that messageID, what
does he do for the new http request which is duplicate due to retry?   I 
say the receiver gives
a fault message as http response to the second http request with info 
that the original request
was received, but its response is being held due to wating for a prior 
message.

There are two http requests outstanding from the sender, and the fact is 
that the second
http request is responded first with a fault (which is really a reply 
with information about
the status of the message) message.  Later, when delivered, the receiver 
returns a response to
the original http request with an ack.

Note that the first http request could wait a long time for a response.  
If the TCP connection
goes down, what does HTTP do to get the response back to the sender?

Tom Rutt

PS: this discussion is about a potential new issue, and is not part of 
52/57 resolution.


>
> Take the case of ordered group in which msg. 2 was missing and msg. 3
> of received. Since it is not delivered, it will not be Ack-ed. Assume
> your new proposal. If msg. 3 is tried, a NewDuplicateMsg fault will be
> sent. Assume 2 was finally delivered. Then the receiver will send the
> original Ack...
>
> For Sender, it will be very confusing to receive the Ack. AFTER receiving
> a DuplicateMsg. fault.
>
> -Sunil
>
>Tom Rutt wrote:
>
>  
>
>>Based on our current thinking, we are not sending an ack until the
>>message is actually delivered.
>>
>>Thus in the ordered delivery held waiting for prior message state, an
>>RMP may receive several
>>retransmits of that held, and thus not acknowledged message.
>>
>>In such a case, the receiving rmp should respond to sending rmp
>>regarding its receipt of the duplicate message with an appropirate
>>DuplicateMessage fault.
>>
>>Please correct me if I am wrong, but I think we need to clean up the
>>semantics of this from what is in the current draft.
>>
>>Tom Rutt
>>
>>--
>>----------------------------------------------------
>>Tom Rutt                email: tom@coastin.com; trutt@fsw.fujitsu.com
>>Tel: +1 732 801 5744          Fax: +1 732 774 5133
>>
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>>    
>>
>
>
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>
>  
>


-- 
----------------------------------------------------
Tom Rutt		email: tom@coastin.com; trutt@fsw.fujitsu.com
Tel: +1 732 801 5744          Fax: +1 732 774 5133