Re: Re: [OT] Asterisk at home help + XAP integration

["christopher purves" <CHRIS_PURVES@xxxxxxx>]

Very nice description.

On another topic -  as promised I will soon be able to get round to
properly
using your gateway! Its permanently installed now and sits along side the
wireless stuff - will see how they behave - a comfort cbus interface is
also
there.

Chris

>From: Kevin Hawkins <lists@xxxxxxx>
>Reply-To: ukha_d@xxxxxxx
>To: ukha_d@xxxxxxx
>Subject: Re: [ukha_d] Re: [OT] Asterisk at home help + XAP integration
>Date: Wed, 19 Oct 2005 14:38:02 +0100
>
>Patrick Lidstone wrote:
>
>  >>>        Chris Purves wrote:   I always struggle to
understand the
>difference between xap and xpl.
>
>Put very simply, xPL can be thought of as a "light" version
of xAP.
>
>___________________________________________________________________________________
>
>     Well - not sure even I as a 'xAP' person would simplify it that
far
>!      xAP vs xPL is a highly emotive topic   -  inevitable with any
>open projects like these. The xPL founders were members of the xAP
>specification committee and the split ocurred due to differing
>objectives,  technical disagreements and subsequent personality
>clashes.  I'm trying not to stir the embers here but as I use both I
>thought I might be best placed to impartially address the above , (but
>do bear in mind I am xAP allied).
>
>     xPL originally took the xAP protocol and adapted it , essentially
>reducing the addressing capacity (address length), defining a fixed
>number of key message types  and removing some of the more advanced
>ideas - the rationale being that xPL was a solution for home HA
>enthusiasts rather than 'commercial' and so some of the extra xAP
>features weren't needed, xPL could achieve capable solutions for the
>developers own HA setups and that was the objective. xPL also stated
>they would never change their core protocol to preserve total future
>compatability. Also reducing the addressing lengths would enable xPL to
>be implemented on smaller processors.  (actually  a xAP device can
>recognise any other device using a 4 byte address so both are now very
>tight here) .  Hence xPL adopted the 'lite on the wire' tag line . In
>practice as smaller devices eg PIC's have become more and more capable
>(for very low cost), implementing either protocol on such tiny devices
>is very achievable and indeed there are commercial PIC based xAP
>products on the market complete with inbuilt Ethernet support (eg the
>Netiom). The applications that are available for both xAP and xPL have
>tended to be running on desktop machines and using Ethernet too so the
>capacity issue goes away.  It is quite desireable though for HA users
to
>not be dependent on a desktop OS for their home to operate hence the
>thrust towards embedded solutions. In relative terms xAP and xPL are
>very compact although there are even smaller protocols like CAN SNAP
>C-Bus etc, which suit low speed communication eg slow radio / RS232
>serial links.
>
>Since the split both xAP and xPL have extended their capabilities.
>Typically this is done via adding policy layers on top of the base
>protocol. Hence all applications still work but new aspects can be
added
>like 'discovery' 'configuration' 'plug and play' etc and many
"schema"
>have been defined which address concepts rather than devices eg 'whole
>house audio'  'on screen display'  'caller id' 'weather' etc. These
>schemas are a way of abstracting a  device such that you actually
>control a virtual device eg an 'mp3 player' rather than a Rio or a DDAR
>or Slimp3 - theoretically then when you swap your Slimp3 for a Netgear
>101 player it all continues to works as it did before. It is important
>to support these abstract devices rather than implementing a schema for
>a specific piece of hardware.  In all these areas the two protocols
have
>significantly diverged and hence become increasingly incompatible.
There
>is some ability to 'bridge' between the two but it is not always
>achievable.
>
>xAP has looked to include support in the typical commercial HA
>applications available today to blend with your existing setup, 
whereas
>xPL focusses on  their own xPL HAL as a free centralised management /
>controller application. xPL also tends to be  a practical solution
>created for the needs of it's users whereas xAP has tried to market to
,
>and get more involvement and support with the outside world and
>commercial developers. For xAP (or xPL) to survive this is important.
>xAP has some  glitzy 'user interface' applications too like xAP
Desktop,
>xAP TouchScreen and xAP Floorplan  (AJAX web based) and also works via
>XLobby or MainLobby etc.  xPL has less 'eye candy' here (but that is
>being addressed) but has better  support for scripting and supports
>'determinators' (sort of templates/wizards) for helping new users
create
>scripts, it has inbuilt support within xPLHAL for configuration too.
>Both xAP and xPL offer free VBscript based control environments.
>
>As such neither solution can I feel be seen as a subset of the other,
>xPL has addressed several concepts that xAP hasn't and vica versa..
They
>are both based on the same core 'protocol' and the xPL implementation
is
>tighter here (imposes length restrictions and excludes certain
>parameters which arguably could make it easier to implement) but the
>important fundamentals are all there and almost anything can be
achieved
>in either protocol.   I have always been disappointed that both exist,
>because it causes confusion, duplication of effort and more importantly
>we are both small groups trying to offer solutions - if we were both
>pulling in the same direction we would have twice as much impact.
>Incidently UPnP (Universal Plug and Play)  is a  similar concept backed
>by big industry names , and I think it will become quite ubiquitous in
>the next few years. You will be able to buy consumer goods with UPnP
>inbuilt , indeed Sonos, Escient, Netgear, Roku etc all offer it
already.
>However 'easy' or 'lite' it certainly is not, being maybe two orders of
>maginitude more 'bulky' than xPL or xAP, which puts  it well outside
the
>capabilities of most enthusiast programmers and small embedded devices.
>This is what is so great about xPL/xAP - for the first time they offer
a
>way of networking / interacting with all your devices and it is
>achievable with relatively little programming aptitude. Neither are yet
>truly accessible to every 'end user' - you need a bit of programming
>expertise - but not a lot beyond simple VB scripting - and both are
>slowly getting better in this regard. I have achieved so many things in
>my own home using xAP as it provided the methodology to link it all
>together.  The xPL'ers have done likewise.  xAP and xPL enable it.
>
>     Kevin
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