Re: Re: Look ma, no hub?

[Jean-Paul Figer <jfiger@xxxxxxxxx>]

The question is not what you can do or not. I prefer an USB bus instead of
com1, com2, lpt1 not for added features but for the new flexibility I get :
same plug, hot plug and play, ...
In a design, it's always better to have loosely coupled functions and the
hub is a perfect way to decoupled functions.
I have been able to add TTS functions to my legacy home automation system.
It was painful. With a hub, it's a non event.

--
Jean-Paul Figer

On 11/17/05, Mark Hindess <xpl@xxxxxxx> wrote:
>
>
> On 17 November 2005 at 19:44, Jean-Paul Figer <jfiger@xxxxxxx>
wrote:
> >
> > From an architecture point of view, the hub is a key component of
a
> > distributed Home automation system. Being able to interconnect
X10,
> Asterisk
> > PBX, Winamp, my old home automation system, text to speech, IR
and more
> in a
> > fast and coherent way is a strong advantage. The hub concept is
more
> > important than the Xpl protocol.
>
> Please explain what you can do with a hub that you couldn't do
perfectly
> well without one if your system (like Linux) supports binding to the
> same port by more than one application? If they can do this, then all
> applications will receive all the messages that would otherwise have
> had to be forwarded by the hub.
>
> I think that from my testing that anything you can do on Linux with a
> hub will work just as well without one. I'd love for you, or anyone,
to
> point out precisely what functionality I'd be missing if I didn't run
a
> hub.
>
> > Please keep the hub.
>
> Why exactly? Personally, I'm usually quite glad when I can remove
> something that is a single-point-of-failure. I'd have to have very
good
> reasons to justify keeping it.
>
> Gerry has some good points about platform independence. However, I'm
> still not convinced since it is trivial for any platform independent
> application to test if it is possible to bind to the same port twice.
> The application just has to:
>
> 1) create a socket with the reuse addr socket option
>
> 2) bind to port zero - so the system allocates the socket an unused
> port
>
> 3) create another socket with the reuse addr socket option
>
> 4) bind to the port that the system allocated in step 2
>
> If any step fails then reuse addr is not supported and it should use a
> hub.
>
> A similar test could be added to any application - for instance, a hub
> could do this and refuse to start if it is not required.
>
> Personally I'd not have a problem requiring applications (and hubs) to
> perform this test on all platforms.
>
> Sorry to cause trouble here, but I think it is important to justify
> having single points of failure.
>
> Regards,
> Mark.
>
>
>
>
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> http://www.xpl.myby.co.uk
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