Messaging in Py?

[Kendall Clark]

> What you're looking for is an asyncronous publish subscribe
> text and/or serialized object delivery service between mutual
> peers? With possible serialization using xml pickle, but
> even better, with extensible/plugin-based serialization?
> Would the backing store be for session rejoin / recovery,
> or did you have something else in mind?

Bravo! *Exactly* what I was thinking. Though I'd like to be able to
mix pub/sub and point-to-point since in my problem domain you often
want subscribers to receive all the messages in a particular channel;
but sometimes you want messages only routed to particular subscribers.
And in the former case you
don't care if every message is delivered, while in the latter you do.

The idea of subscribers using XPath expressions to filter messages
they're
interested in comes from XmlBlaster(.org), and it strikes me as
wickedly
clever.

(People sometimes think pub/sub has something to do with content
management necessarily; but in this case it's a useful misreading
since that's precisely what I want it for.)

One reason I'm not enthusiastic about Elvin is that it doesn't
support Python object serialization, only 'primitives' (iirc,
ints, floats, strings -- I guess you could stuff non-bin pickled
objects into string types, but ick!). In its favor, it has several
useful client implementations, making it fairly cross-platform. But
I can live with a pure Python solution since most subscriber clients
will be Web-based anyway.

> I'm asking you this, because as it so happens I'm working on
> a _paid_ government research project at the moment in this
> area, and am in the process of developing a reliable,
> channelized UDP layer to support much of this. While my
> primary work is not in Python, much of the first pass prototype
> work is.

Hey, that's very cool! Maybe you could open source your prototype
and turn it into a community project, as you suggest. I happen to
think Python is ideal (because of it's excellent network, XML, and
object serialization support, not to mention SOAP and XML-RPC imple-
mentations, and it's dynamicness. Plus, I really like Py. :> )

> If I got a CVS tree root up on source forge, I wonder how many
> people would be interested in working on it? I might do the
> initial work, and then give it to the community. The government
> would probably be as happy as pie to successfully host a
> worthwhile open source effort.

You think the *gov't* would be happy? As a taxpaying Python
hacker I'd be *thrilled*! 
 
Hopefully I'm not alone in that and a show of support from
some other Pythoneers can help you make the case to your 
bosses.

Best,
Kendall Clark, Monkeyfist.com