xAP/xPL - Building a Bridge ( in more ways than one ;) )

[Ian Lowe]

It's apparent from the discussions of the last two days that the current
xAP/xPL situation is in no-one's interests. It's also clear that the
underlying reasons for the initial Split still remain. What we need,
however, is some form of cooperation and working towards the mutual goals
we
share.

The xPL team discussed the various technical challenges on our side
overnight, and had further useful discussions with the xAP team this
morning. We have pretty much confirmed that the initial doubts about a
bridge are well founded: the likelihood of confusion when a richly
addressed
xAP message is truncated to meet the stricter xPL sizes is pretty high.

It seems to us, therefore, that the best solution is to incorporate a
gateway between the two protocols into the xPLHal engine. It is an
intelligent scripting system, and ideally suited to the (quite complex)
task
of rewriting message components between the different formats.

We think that the following could work, and provide a good degree of
interoperability:

1) We will produce a new version of the xpllib.dll, allowing the xPLHal
service to connect to a xAP Hub, and pass incoming xAP messages to the
xPLHal engine as a block of text.

2) We will add an event within xPLHal to trigger when a xAP message
arrives,
of the format Sub xAP_<vendor>_<device>_<msgtype> (msg as
text) xAP
scripts should be stored in files with a .xap extension, as per the .xpl
scripts

3) We will add a function within xPLHal called "xap.getparam" to
mirror the
existing "xpl.getparam", this returns the value of a specific tag
within the
xap message, allowing the contents of xAP messages to be used in xPLHal
Scripts

4) We will add a function called "xap.sendmsg" to reflect the
"xpl.sendmsg",
The automator builds a xap message as a string of text, then passes it to
this function, which will allow the xPLHal engine to send xap messages.

This will provide the tools to allow Automators wishing to use both xAP and
xPL to write scripts in vbScript that can react to, and send xAP messages,
as well as the xPL support already present. We think that this will
"Open
Up" xAP and xPL to each other, and the only thing that can happen is
that
everyone benefits.

Ian.
(On Behalf of the xPL Team)