Re: Re: Look ma, no hub?

[Gerry Duprey <gerry@xxxxxxxxxxx>]

Howdy,

> I thought the hub was an implementation detail, specific to the
> transmission of xPL over UDP in a Windows environment?  It's not
> part of the xPL protocol itself.  If the platform doesn't require a
> hub to function, I see no need to require as part of the spec.
>
> However, being able to run without a hub means binding to the xPL
> port rather than 50000+.  You would have to be sure that all other
> Linux xPL apps could run hubless (ie don't just assume that there
> will be a hub), and that all versions of Linux support multiple apps
> binding to the same port.

Well, here's lies my earlier note about confusion.  Even apps running under
linux are not all going to be able to do this.  Consider multiple-platform
apps (xPL4Java, the perl and python bindings, etc).  They have to be
written
to support the most common config available on all platforms and that would
rule out being able to bind directly under linux (without linux specific
code -- then what about OSX, solaris, AIX, etc...).

Worse, if a linux-only app did bind directly to the port, any subsequent
multi-platform app started on that computer would not function.  Since the
linux only app is bound to the port, the multi-platform apps are going to
wait until a hub (which doesn't exist) starts sending them messages.

So know you need to know if the apps you are running are linux only and
support a no-hub mode or a mix of these and others that are either
multi-platform and/or do not support a no-hub mode.  Then you need to
decide
to run a hub (and if you have a mix, you need to start the hub first or it
will die when it starts and finds one of the hubless apps already
listening).

I believe that technically, the hubless stuff can work and for folks who
understand the implications, a mixed hubless and hub-based environment can
be made to work.  However, I see making it all work for the average person
in a mixed environment to be difficult.  Knowing which setup each app they
want to use needs, starting things in the right order, etc, etc.

That is my concern -- an xPL app creator cannot provide a simple set of
directions for installation (Step 1 -- confirm you have a hub and install
one if not.  Step 2 -- install this app).

Gerry
--
Gerry Duprey
Ann Arbor, MI 48103
http://www.cdp1802.org