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Subject: RE: [ws-rx] Proposal for closure of Issue i022, RM Assertions


Title: Message
+1
Abbie
 
 
-->This is the Way  --> This is Nortel
-----Original Message-----
From: Marc Goodner [mailto:mgoodner@microsoft.com]
Sent: Friday, October 21, 2005 7:49 PM
To: Bob Freund; ws-rx@lists.oasis-open.org
Subject: RE: [ws-rx] Proposal for closure of Issue i022, RM Assertions

+1 to the proposed modifications here. I would be supportive of a new issue being filed as described below.

 


From: Bob Freund [mailto:bob.freund@hitachisoftware.com]
Sent: Friday, October 21, 2005 5:11 AM
To: ws-rx@lists.oasis-open.org
Subject: [ws-rx] Proposal for closure of Issue i022, RM Assertions

 

Argument:

Retransmission parameters as well as algorithms are problematic for the following reasons:

1)       The characteristics of the path from source to destination are often unknown and often are time-variant.

2)       Retransmissions if too frequent cause flooding and potential catastrophic degradation if the path is near saturation

3)       The path may consist of not only transmission means, but also intermediaries with attendant processing delays

4)       Exponential back off may be implemented many ways, there is more than one algorithm that use different parameters

5)       Back off algorithm selection may be implementation specific, what is good for cell phones may not be good for cluster interconnected nodes or crossbar connected multiprocessors

6)       I have found no theoretical modeling published concerning stability of specific back off algorithms which consider the case of web services cum intermediaries

7)       Most published data concerning the behavior of back off algorithms examine fairly simple network segment related saturation and do not address client, server, let alone intermediary saturation.

8)       Exponential back off algorithms need an adaptive recovery mechanism for those situations where there is a high standard deviation of delay.

9)       TCP/IP experience has shown that efficiencies are improved with an adaptive mechanism as described in TCP Extensions for High Performance (see RFC 1323 RTTM)

Proposal:

Clearly a back off mechanism is required; however implementation specific needs are not served well by the specification of any specific algorithm for all potential implementations of WS-RM.  It is recommended that implementers utilizing IP based transmission media consider the mechanism described in RFC 1323.  In additions, acceptance of this proposal removes all mention of re-transmission which is a required for correct operation of the protocol. These however are beyond the scope of the issue as stated.

Therefore:

Delete all re-transmission parameters as described in the WS-RM Policy specification [1] since they are unnecessary and unhelpful should the implementer use an algorithm with a different set of controls.

 

Note:

A new issue should be opened to address the location and manner by which re-transmission behavior is specified.

 

Thanks

-bob

 

Specific modification to documents:

In [1]

Delete lines indicated with cross-out in the attached document,

Adjust portions highlighted in attached document to reflect line number modifications resulting from deletions

 

References:

[1] WS-RM Policy WD DTD 2005-10-19



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