Re: Proposal for VSCP schema

["Mark Harrison (Groups)" <mph@xxxxxxxxxxxxxxx>]

On Mon, 2005-08-08 at 08:14 -0400, Gregg Liming wrote:
>
>
> This limitation is (IMO) very limiting to those of us creating xAP
> gateways for systems that have many more than 254 devices and
> inevitably
> causes "hacks" to be required to handle the mappings.  I'm
personally
> hoping that the xAP spec will be revised soon to support a much larger
> number of subaddresses.  In the mean time, I've had to resort to
> "virtual" subaddresses that nominally map to semi-natural
groupings of
> devices.  Even this technique, however, doesn't scale well and will
> break if pushed.

We discussed this at xAPCon04, and ISTR that everyone was in favour of
extending the size of UID.

I note that Kevin is going to push this forward, though for the record,
my preference is for 2N8A8S

That having been said, I'm in favour of the "majority decision"
on which
length they should be because a quick decision is more important to me
than the difference between 2N8A8S and 2N6A6S - either is enough for the
immediate requirements.

If nothing else, it would make the BSC handling in xAPHomeVision _much_
easier - at the moment, we map each house code on to a different xAP
Device, to allow the full 256 X-10 devices - the 254 limit was terribly
annoying. (I realise that xAPHomeSeer has a different set of
constraints, because of the way that HomeSeer allows virtual X-10
devices.)

If truth be told, the BSC Support in xAPHomeVision is good, but the X-10
Schema support is fairly flakey. I'd be in favour of getting the UID
issue resolved ASAP, so we can rewrite the X-10 stuff cleanly!

One key question though - will extended UID be enough to push v=12 up to
v=13? I think, realistically, yes, in which case we may want to consider
message fragmentation at the same time - though the "get it done"
rule
is again more important to me.

M.