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

["Edward Pearson" <edward.mailgroup@xxxxxxxxxxxxxxxx>]

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@xxxxxxx] On
Behalf Of Paul Gale
> Sent: 09 June 2009 11:01
> To: 'xap_automation@xxxxxxx'
> 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@xxxxxxx] On
Behalf Of turner228
> > Sent: 08 June 2009 21:15
> > To: xap_automation@xxxxxxx
> > 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, "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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