Re: [wsrm] What about this tradeoff solution for the persistence issue?

["Jun Tatemura" <tatemura@ccrl.sj.nec.com>]

I don't understand why we should specify
the crash tolerance level in a message.

My understanding is that WS-RM relys on message parsistance to achieve
the three functionalities (i.e., guaranteed delivery, duplicate elimination, and message
ordering).  If it is true, the specification "mustpersist=false" does not make sense
since, without message persistance, WS-RM does not provide any reliability.
(Of cource, the level of persistance reliability may differ from main memory to
hard disks.)

If "mustpersist" is meant to specify the level of persistance reliability,
the boolean is too simple -- the level of persistance reliability is not
all-or-nothing.

Moreover, even if we can specify crash torelance in a message,
we still need some agreement before establishing reliable messaging
(such as retry interval, maximum time-to-live, ...).

My opinion is that we should use a (yet-to-come) standard for (service level / policy) 
(description / agreement / negotioation), which is orthogonal to WS-RM.
Since we can't expect such a standard within our timeframe, all we can do
is to list up what sender/receiver should agree on (how to agree should
be out-of-scope), such as message persistance reliability, retry interval,...

---
Junichi Tatemura

----- Original Message ----- 
From: "Paolo Romano" <Paolo.Romano@dis.uniroma1.it>
To: <wsrm@lists.oasis-open.org>
Sent: Monday, June 09, 2003 5:15 PM
Subject: [wsrm] What about this tradeoff solution for the persistence issue?


> 
> Persistent storage usage is the default mode.
> An apposite <mustpersist="false"/> tag is used when applications do not require
> a crash tolerance reliability level, but only tolerance to transport layer
> failures.
> In case a device which is not able to persist a message receives a message
> without the <mustpersist="false"> element, a fault message MUST be sent in
> response, indicating the inability of the receiver to assure required
> reliability guarantees.
> In that case it is up to the application layer to decide whether to send again
> the same message requiring a lower quality of service.
> 
> It seems to me to be very simple, needs only to define two reliability levels:
>              (non-destructive) crash tolerance
>              transport layer (communication channel) failure tollerance
> 
> By default <mustpersist="true"> even if not specified since it is the most
> common use case.
> No need for negotiation, reliability level is estabilished by the sender, and
> possibly refused by the receiver.
> ..
> And cell phones users (and surely mobile developers too!) will be happy not
> being bothered anymore by disconnections when driving into tunnels!
> 
> Comments?
> 
> 
> --
> Paolo Romano
> 
> 
> 
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> 
>