Sorry for jumping in late on this...
Federico Barbieri wrote:
>
> Last days I was wondering what is the best way to define mail servlet
> interface.
> I looked both at Serge implementation and Stefano and Pier Mail Servlet
> draft and I realyze there is a limitation: both definitions allow a mail
> servlet to receive only one mail as "request" and generate only one
> "response".
Yes, both were designed to _impose_ such a limitation. I remember an old
time discussion on this mail list about that.
> This is enought for mail servlet like a mailinglistservlet which only,
> from the request message, expand recipient list and add some footer.
> My point is: do we need a mail servlet to produce more than a response
> from an incoming message?
<strong-opinion>
we don't!
</strong-opinion>
I had a long phone discussion with both Federico and Pier about this:
mail forking should be considered "flexibility syndrome" and avoided as
a plague. The reasons are:
1) a filter is _never_ meant to be a multiplexer
2) a filter has one channel in and one channel out... if other
communication is needed, this is performed sideways (the T-model from
electronic filters).
in ---> filter ---> out
|
V
signal
3) all possible "signaling" requirements are system operations (logging,
error checking, profiling information) and do not belong to "normal"
mail servlets.
> I was thinking to something like a mailservlet whitch examine incoming
> messages and produce a new mail if some condition occurs. In this case
> one message enter the mail servlet and one or two (the old untoched
> message and the new one) different messages exit.
This hurts the overall cleaness of the design, IMO.
> Another example can be some translation servlet which translate incoming
> messages to the user preferred language:
> I can write
>
> <processor match="to=mario@[localhost] or to=natasha@[localhost]"
> class="Translator">
> <translate user=mario language=italian/>
> <translate user=natasha language=russian/>
> </processor>
>
> This meand the servlet take the same message sent to mario and natasha
> and produce two different output messages.
>
> Since such things cannot be done using both Serge or Pier and Stefano
> pattern I was wandering if someting more powerful could be needed.
This is not right: this can be easily done with a filter approach. In
fact, the mail list servlet will expose more reciepients, then feed the
mails back into the reactor. At this point, the mail is "translated" on
a single reciepient base, like in any other processes.
I could not come up with a need for forking that doesn't involve the
sideways signaling model explained above.
So, my vote is a big -1 to forking.
> Am I on the right way or just thinking too big?
I believe this is big time flexibility syndrome.
--
Stefano Mazzocchi One must still have chaos in oneself to be
able to give birth to a dancing star.
<[EMAIL PROTECTED]> Friedrich Nietzsche
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