RE: Feedback from UHKA 2003

[Kevin Hawkins]

Overall I have to say that I think xAP came out quite well at UKHA although
a lot of people are sitting on the fence about using or implementing it. If
we can get xAP support in Harmony, Autom8it, HomeBrain plus ACE and
HOMESEER
- the last I see as critical then this would help a lot. We also need the
HomeVision xAP connector and we have MisterHouse already. Certainly there's
a huge demand for a protocol to do what xAP does - we just need to
facilitate this at the end user level.

What I did learn is that a few people had tried and failed to get
the existing xAP applications all working together - and had been too shy
to
say so. I also had a rather tricky issue with some incorrect Ethernet
interfaces being identified and used by xAP so I think we need to establish
that all the current aps and hubs work interchangeably without problem
across various platforms and that in machines that do present this eth0/1
issue it is handled too. I see on this list that Bruce posted about this
problem a while back with the MisterHouse announcement.

The other thing I learned is that a large number (the majority) of
the UKHA list are not comfortable with programming and need to see xAP
delivered in a more 'end user' usable fashion - hence the desire to support
the main software / hardware that people use at home now/today. I think
this
is absolutely key. Some more people have a VB script knowledge but couldn't
for example cope with an OCX.

I'm going to step up to the mark and try and deliver a very basic
tutorial along with some very basic apps to encourage the novice
programmers
into the fold.

Having some xAP hardware available too will be great - although I
was a little taken aback by some of the things Mark talked about - sort of
felt a little 'uninformed'. I have to say Mark did a really cracking
presentation and it certainly raised the bar and the professional image of
xAP no end - well done Mark. We also had a great demo that 'enticed' people
with its simpilicity/complexity - what I mean is Patrick demonstrated
technically a very complicated solution that was implemented with such
apparent simplicity - which has to be a great sell to anyone.

The other thing that came out from the developer side (for example
David Buckley) is that the flexibility of xAP (which he loves) creates a
problem in quite what 'xAP support' means and the complexity of supporting
'devices' within an application like HomeBrain or Autom8it for example.
Over
the discussion I think we saw a need to define for a 'base level' device a
few parameters that are mandatory in every device type message including an
ON/OFF status and a level status expressed as a percentage probably - this
maps well to most (almost every) type of controllable device. In this way
every xAP device could be represented within an application assuming it
included a

Mode=ON
Level=20%

Or something similar - perhaps raising the issue yet again of class
inheritance within the way we structure class.type section.sub etc

Dwelling on my conversation with David B (and Patricks' below) there is
some
validity to the end to end integrity worry - not so much an issue on
ethernet but certainly on lower speed (RS485/232) or bridged networks.
Sequencing is obviously an option but as P says below this raises a whole
range of other issues to do with the broadcast/targeted model. We should
talk this through though.

I had wondered about the possibility of including a 'ACK=Yes' type
parameter in targeted messages to effectively confirm delivery of a packet
-
although this is a sender to receiver mechanism only (it wouldn't handle
the
receiver knowing it had missed something). Using this for example a
security
sensor could broadcast its status generally (broadcast) and additionally
target a critical receiver with an ACK=Yes mechanism. Towards the end of
our
discussion David seemed happy that if we could include this sort of
mechanism - plus the standard (universal) parameters for ON/OFF and level -
along with additionally a defined and standard way of polling the status of
a device then he would be very happy with xAP - he loves the higher level
stuff (text display - DB lookup etc). I think this last bit of defining a
status.request along with a status.report type schema that includes the
ON/OFF and Level would help everyone here. Maybe there's more than level
but
I think most HA applications (and devices) only support this need.

Obviously we need to address configuration and discovery as well
(untargeted message with Ack=Yes).

Just some thoughts - DanH (Ace) said similar things - and Craig
(HomeVision) too saw the freeform format of xAP as being impractical for a
state model within HV. Being content with ON/OFF/Level (or even just level
with 0% and 100% being ON and OFF solves this)

K


> -----Original Message-----
> From: Patrick Lidstone [mailto:<a
href="/group/xAP_developer/post?postID=MljXyrMgHcPlnMgu7ZN8gnv48AlwkeduY3AqjYxDIS2aJF-HodmVnHVUQjGnqYvc1-oSQMtVW4sg7g">patrick@l...</a>]
> Sent: 19 May 2003 11:56
> To: <a
href="/group/xAP_developer/post?postID=-dc20SG8I2FWtPCD0mwdX3cTJF_anfJ2a8t_o1SuA7jutR5V0Ec-dtNcIYSLqQG-R74iaOseFzit2RBhA_ZFV6_rCck">xAP_developer@xxxxxxx</a>
> Subject: [xAP_developer] Feedback from UHKA 2003
>
> Some feedback I got about xAP from UKHA 2003.
>
> - David Buckley pointed out reliability is an issue - xAP messages
> can potentially be dropped by the network (although I've never seen
> it happen yet, I agree it *could* happen). I think we can solve this
> to a certain extent by including an optional sequence number in the
> header - the receiver could then potentially detect a missed message,
> but there are a number of subtleties involved here, and I don't think
> we want to add any more complexity to the protocol - perhaps with a
> bit of imagination we can come up with a cheap &amp; easy fix?
>
> - Ian B. has done a great job on device configuration (and I was able
> to get serial bridging working just fine with his relay board at the
> meet - cool!). I think we should review his mechanisms and ratify
> them/something similar as the de-facto standard.
>
> - People asking "what are we going to do about.../when will you
have
> support for...". I think it would be worth putting together a
> wishlist and roadmap of where we hope to be in terms of apps etc over
> the next few months.
>
> I think that's about it. I had a good time, even if my head didn't :-
> ), and it was good to catch up with fellow xAP developers.
>
> Patrick
>
>
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