Re: Re: xAP vs. xPL: Differences, Benefits

[Kevin Hawkins <yahoogroupskh@xxxxxxxxxxxxxx>]

Just a few more to add to the pot...

xAP supports a pseudo hierarchical  source address structure, each
segment delimited by the period character , and the number of segments
is not fixed in xAP but is in xPL (to two). You can use this feature for
any purpose you desire , or not at all.

In xAP we have wildcarding addressing  using the * or > character, to
target or filter messages, identifying  subsets/groups of devices. xPL
does not support this wildcarding although it does have an address
'everyone' ability.

eg a sample device address
Source =ACME.lighting.control.upstairs.landing

Target=*.lighting.*.upstairs.*
to send a message to any/all the lighting controllers upstairs

When a device or application has many end nodes within it - for example
a 16 output relay board - then xAP has an addressing identifier to
clearly show the parent and identify the endpoints contained within it
(sub addresses).  These endpoints can again use the pseudo hierachical
addressing to offer clearer identification or grouping of functionality
eg 'inputs' 'outputs' 'analog.in'  'analog.out' etc.   Discovery can be
made of all of devices endpoints and their capability using BSC.

xPL permits duplicate parameter names to appear within the message block
and applies a top to bottom time inference to these. xAP does not permit
duplicate parameter names but instead offers multiple bodies within one
message (which then allows coincident changes).

Higher level protocols can be neatly layered on top of both the xAP or
xPL core protocol  , using bidirectional schema definitions . It is here
that the protocols have diverged the most, and contine to do so.  xPL
has implemented a configuration protocol and xAP has a a very effective
schema called BSC (Basic Status and Control) which provides very near
'plug and play' type interoperability between xAP applications.  I'm not
up to speed on xPL but ISTR they may now have some other useful
administrative protocols as well.

xAP has very much taken the approach of trying to allow you to use your
existing favourite HA application - by either getting xAP included
directly within these applications or offering free plugins . Almost all
leading HA applications and grpahic front end applications now have some
form of xAP support - and we have our own excellent  free ones too.  xPL
, as Edward says has focussed around a more contained system.

There are now around a dozen hardware devices with xAP embedded allowing
you to integrate them with your HA setup, there is even a standalone xAP
controller.  I'm a great advocate of this implementation style as it
offers very high resilience with no PC required.  You then use your PC
to layer the more complex integration and the handling of richer data.


K









Source


brian.michel wrote:
>
>
> Wow this is great, exactly what I wanted to see. I think I'm going to
> dig into xAP first and see what I can do and then bridge my way over
> and try to incorporate xPL.
>
> Thanks!
>
> --- In xap_automation@xxxxxxx
> <mailto:xap_automation%40yahoogroups.com>,
"Edward Pearson"
> <edward.mailgroup@...> wrote:
> >
> > The current state is that both protocols are well established,
have
> a keen
> > following and many apps developed each for them.
> >
> > When you look at the specs there's little difference - the
'on-the-wire'
> > format for both protocols clearly shows their common ancestry. I
have
> > written code that deals with them both and found it easy since
xPL is a
> > subset of xAP in terms of message format.
> >
> > The clearer difference is at the application level. With xPL you
> really are
> > buying into using xPL-HAL as your central controller and rules
> engine. xAP
> > does mandate what you use to embed your automation rules. There
are
> > advantages and disadvantages to both philosophies; and it's
largely
> a matter
> > of taste as to what you prefer.
> >
> > If you are building your own software then there is no need to
> choose one or
> > the other; as dealing with both is only slightly harder that
dealing
> with
> > one. I can help you with example code (in C#) if that helps.
> >
> > Off the top of my head (more illustrative than definitive) the
main
> > differences in the message formats are:
> > * xPL defines smaller limits on identifier sizes and is generally
more
> > terse.
> > * xAP has both a numeric (UID) and text (source) description of
the
> message
> > sender. No UID in xPL.
> > * xAP allows multiple message blocks in the message body; xPL has
one.
> > As you can see the differences at this level are pretty slight.
> >
> > Higher up:
> > * xPL defines, as part of the protocol, a common type structure
> (command,
> > status etc) for messages. xAP does not mandate that in the
protocol
> > definition but lets the schema definitions do that. Schema such
as
> BSC and
> > TSC define very similar concepts.
> > * xPL defines a mechanism for device configuration (using
xAPLHAL)
> and xAP
> > does not.
> >
> > The difference in the range of applications available for each
> protocol says
> > nothing about the suitability of one or the other for a given
> problem - it's
> > just an indication of the areas of interest of the followers of
> each. But if
> > one has your 'kiler app' already then that's one means to choose.
> >
> > HTH
> >
> > Edward
> >
> > > -----Original Message-----
> > > From: xap_automation@xxxxxxx
> <mailto:xap_automation%40yahoogroups.com>
> > > [mailto:xap_automation@xxxxxxx
> <mailto:xap_automation%40yahoogroups.com>]
On Behalf Of Paul Gale
> > > Sent: 09 June 2009 11:01
> > > To: 'xap_automation@xxxxxxx
> <mailto:%27xap_automation%40yahoogroups.com>'
> > > Subject: RE: [xap_automation] Re: xAP vs. xPL: Differences,
Benefits
> > >
> > > Yes, I agree - it's really down to which apps you need - no
reason not
> > > to run both!
> > >
> > > For me it was killer apps like switchboard and Kevin H's
CBus-
> > > HomVision-xAP hardware gateway that sold me on xAP :)
> > >
> > > Paul.
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: xap_automation@xxxxxxx
> <mailto:xap_automation%40yahoogroups.com>
> > > > [mailto:xap_automation@xxxxxxx
> <mailto:xap_automation%40yahoogroups.com>]
On Behalf Of turner228
> > > > Sent: 08 June 2009 21:15
> > > > To: xap_automation@xxxxxxx
> <mailto:xap_automation%40yahoogroups.com>
> > > > Subject: [xap_automation] Re: xAP vs. xPL: Differences,
Benefits
> > > >
> > > > Hi Brian
> > > >
> > > > I am not sure that describing xPL and xAP as feuding is
particularly
> > > > relevant to the current position. Certainly it is true
that there
> > > were
> > > > disagreements many years ago when xAP first started,
and some went
> > > > their own way but I am not aware of any 'feuding' going
on now.
> > > >
> > > > However all this was long before I got involved in
using and
> > > developing
> > > > my own applications. My decision on choosing xAP was
not based
> on any
> > > > philosophical approach to home automation but was based
on the
> fit of
> > > > the then available xAP applications to my needs, and
availablity of
> > > the
> > > > tools and information that I needed to create my own to
fill the
> > > gaps.
> > > >
> > > > Since that time a wide range of xAP applications and
hardware have
> > > > become available and a number of other applications
have
> included xAP
> > > > support as well. xAP Floorplan even provides a bridge
to xPL....
> > > >
> > > > Kevin T
> > > >
> > > > --- In xap_automation@xxxxxxx
> <mailto:xap_automation%40yahoogroups.com>,
"brian.michel"
> > > > <brian.michel@> wrote:
> > > > >
> > > > > Hey all,
> > > > > I currently want to start my own home automation
environment, and
> > > > have found the two feuding protocols, xAP and xPL. I'm
trying to
> > > decide
> > > > which one to go with, however they are both extremely
similar. I do
> > > > know that xPL forked from the xAP code, but I cannot
find out why,
> > > and
> > > > what differs between the two protocols. Is one better
than the
> other,
> > > > do they provide the same things? They seem to almost be
identical,
> > > but
> > > > I'm having a hard time locating exactly where the
differences lie.
> > > Any
> > > > information would be appreciated so I can get this
project going!
> > > > Thanks!
> > > > >
> > > >
> > > >
> > > >
> > > >
> > > > ------------------------------------
> > > >
> > > > Yahoo! Groups Links
> > > >
> > > >
> > > >
> > >
> > >
> > > ------------------------------------
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> >
>
>



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