RE: xPL Networking Questions

["Tony Tofts" <tony@xxxxxxxxxx>]

> When using network xPL on a computer, do you absolutely HAVE
> to have a HUB running on the PC you want to run xPL apps on?
> If you have only one app for the PC, can't it just bind to
> port 3865 and be done with it?

The protocol requires a hub, even for a single app. Since the order that
the
hub and app's start cannot always be predetermined an app could start,
assume no hub, bind to the port, this prevents the hub starting and leaves
all the other app's starting totally deaf.

An alternative is to build a hub into each app, but this seemed overkill
&
would rely on every programmer getting the hub code right.

Therefore a separate hub was deemed mandatory and the simplest solution.

> Also, if a single program is advertising itself as a number
> of different xPL devices, is it OK that in the configuration
> broadcast, all the device specify the same UDP port # to listen on?

That's a good question, I'll have to think about that one.

> It appears to me the hub in xPL is a lot "thinner" than the
> hub xAP uses -- does that sound right?  With xPL, it seems
> the only real function of the hub is to multiplex the single
> port 3865 -- xPL apps still brocast by themselves (not
> through the hub).

Correct. The app's handle there own sending, the hub is there only to
mutliplex port 3865. We saw no need to push all the outgoing messages thru
a
hub, since the outgoing ports are irrelevant. It allows the hub to
concentrate on it's prime function.

> I would imagine I'd normally be running a hub, but in some
> small scale cases, it may be the only thing on a dedicate
> mini-linux system is the xPL app and a hub would not really
> be necessary.

See above ;-)

Regards
Tony