What about this tradeoff solution for the persistence issue?

[Paolo Romano <Paolo.Romano@dis.uniroma1.it>]

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