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

[Tom Rutt <tom@coastin.com>]

Paolo Romano wrote:

>  
>
>>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.
>>    
>>
>
>As Sunil pointed out we exstensively discussed about this point in F2F, but I do
>not think we reached an agreement. In fact, also when the protocol state (i.e.
>the information concerning the exchanged messages) is stored in a non persistent
>way, some additional reliability guarantees are still provided by ws-rm, when
>compared to classic TCP based protocols: that is, applications relying on ws-rm
>are guaranteed that their messages will be delivered in face of communication
>channel failures. This use case is common in wireless environments, and was
>originally presented by Nokia members.
>
>Even when you choose to persist, in fact, ws-rm still can fail to provide
>reliable messaging, simply because, whatever redundancy you can imagine, you
>still cannot exclude a priori the event of persistent storage failures.
>In other words, since ws-rm is not a stateless protocol, it can not be crash
>tolerant in case of persistance storage failures.
>  
>
It is my understanding that in these cases the protocol will fail, but 
the user will not get
a positive ack in such cases. 

I do not recal us agreeing on sending persistence level as a message 
parameter.  If fact the way we
defined persistence, and the decision not to define Persistent storage, 
was done to avoid such
a new  level parameter.

Tom Rutt
Fujitsu
trutt@fsw.fujitsu.com